How to Replace a Head Gasket: Petros method

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Petros
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How to Replace a Head Gasket: Petros method

Post by Petros » Sat Dec 18, 2010 1:39 am

How to Replace the Head Gasket on the 3AC Engine

The Toyota 3a head gasket is particularly prone to being damaged from even minor overheating events, you do not even have to get the temperature into the red zone on the temp gauge to damage the head gasket. Also if you have done any performance mods on this engine you chances of damaging the head gasket is even higher. The design of the 3a head does not allow coolant to fully circulate around the area near the exhaust valves, causing a localized area to get significantly hotter than the rest of the head. This will cause premature gasket failure, and why this engine is particularly heat sensitive, and the process for replacing the head gasket is also equally sensitive to proper procedure.

This is the procedure that I have developed for the 3ac engine over many head gaskets replacement jobs. I have incorporated very important modifications to improve gasket durability and to provide better cooling to the head. Also incorporated are procedures used by professional racing teams for installing head gaskets, as well as short cuts that I have found are effective at saving time without compromising the quality of the job. I have also including warnings about what to avoid to prevent damage to the engine and yourself.

To just replace the head gasket only should take 3 to 4 hours, depending how difficult it is to clean the parts, and presuming you do not experience any broken or frozen bolts. If you follow this procedure you will not even have to reset the ignition timing since the distributor stays in place. This saves both time and the need for a timing light. The FSM has you removing more parts than you need to just replace the head gasket, including removing the battery. This is not necessary, but it means you must take precautions not to damage parts or arc the batter terminals. DO NOT PLACE TOOLS on TOP OF THE BATTERY! If you can not help yourself than just remove it. But this adds more steps of course.

In my experience Toyota heads warped badly enough to need to be machine resurfaced are rare, this would only be required if it was badly overheated. Also, most repair shops will strip the head and have it checked for cracks, which I think is a waste of time and money on a Toyota head. I have never seen a cracked Toyota head, it may happen if the engine dropped a valve or has thrown a connecting rod and was bundled up, but even than it is very rare. Most repair shops will also replace a lot parts that are still serviceable and can be reused, and often talk the customer into replacing the timing belt and tensioner, the front seals, the water pump, all the gaskets and a lot of other parts which adds a lot of cost and time to the job. Unless these things need replacing anyway, there is no advantage to do all this extra work.

I will cover in this first installment the procedure for just replacing the head gasket. In later installments I will include more information on rebuilding the head.

Included in this procedure are ways to resurface the block and head in a home shop without heavy machinery.

Tools you will need:

Safety glasses
Drain Bucket
car jack and a Jack stand
10mm, 12mm, 14mm sockets and ratchet handle plus a breaker bar can be handy
14mm deep socket
16" minimum total length of various lengths of socket extensions
10mm, 12mm, 14mm and 19mm (3/4") combination open end and box end wrenches
Flat screw driver
long nose pliers
Torque wrench with 12 to 43 ft-lb (59 N-m) capacity
wide wood chisel or heavy putty knife as a gasket scraper
12" long block of polished granite or smooth steel plate
Soft wire brush, 5/8" dia brush, scotch brite pads for cleaning

Also nice to have, but not essential;
an air compressor and air nozzles
drop light or strong flash light
mechanics gloves


Supplies you will need:

A head gasket, Fel Pro or genuine Toyota (do not waste your time with any others)
Possible you may need a new head pipe to exhaust manifold gasket (usually you can reuse this gasket if it is not damaged)
Possible you may need new O-rings for the by pass tube on the water pump housing (you usually can reuse these as well)
Wet and dry sand paper, 4 sheets 220 and 2 sheets 400 grit
Shop towels plus white paper towels
Carb cleaner spray
WD 40 or similar spray lubricant
Penetrating oil (ATF works excellent for freeing frozen nuts and bolts)
Light grease or specific thread lube for the head bolts
Gasket sealant

You will also need a place to work on the car, preferably on a paved surface and out of the weather (though I have done this job in the rain, in the snow and on gravel parking lots that were not even level, but I do not recommend it).

Procedure to Remove the Head

1. Remove the air filter assembly, two 10 mm bolts on the valve cover, and the center wing nuts.
2. Apply penetrating oil or ATF on the two 14 mm exhaust head pipe bolts to allow it soak.
3. Drain the radiator into a bucket or pan, save the coolant for reuse if you are not going to put in new antifreeze. You can proceed to the next steps while the coolant is still draining into the bucket.
4. Remove the fan belt from the alternator pulley by loosening the alternator, completely remove the upper alternator mount bolt and rotate the alternator (after you remove the belt) all the way to the right to get it out of the way. You can leave the upper mounting bracket in place.
5. Remove the water pump pulley, use the 10mm box end wrench on the pulley. You have to remove the pulley to get to the 10mm timing belt cover bolt behind the pulley, remove this bolt, and the other 10mm bolts on the timing belt cover.
6. Loosen the 14mm bolt on the timing belt tensioner and back off the tension and snug the bolt back down. Slip the timing belt off the cam sprocket and let it flop down out of the way.

This is a good time to inspect the timing belt, if it is not cracked and not missing teeth or chunks of rubber, it is probably okay to reuse it (I have seen cars still running with half the teeth missing off the timing belts!). If you are going to replace the belt anyway you can do it at the same time you replace the head gasket, it will add about an hour or more of time. You will have to remove the radiator (to give you room to work), the front bolt and pulley (sometimes requires a puller), and the lower timing belt cover. It would not be a bad idea to replace the front main seal while you are at it. You will want to get the front pulley off before you remove the head since you will need to fill the number one combustion chamber (through the spark plug hole) with a soft cord to prevent the engine from turning to get off the large front bolt.

7. Remove the fuel lines from the fuel pump, remove the upper radiator hose, remove the vacuum lines that go from the right fender emissions control equipment and the fuel system, and the lines from the charcoal canister (you may want to number or label these to speed reassembly). Remove the heater hose coming from the back of the head. If any of these hoses or lines are bad or questionable, it is best to replace them now since you have them off. Unplug the electrical connectors from the temp sender on the outlet and front of the head, stow the wires out of the way on the right side of the engine. Unplug the two electrical connectors from the carb and the one from the distributor.

Note: You do not need to remove the spark plugs or spark plug wires, nor do you need to remove the distributor. However leaving the distributor installed on the head means it is vulnerable to damage while you are handling the head when it is off the engine, so you must use caution when handling the assembled head. If in doubt it only takes removing a 12 mm bolt, and two vac lines, to remove the distributor. But if you remove it, you will have to reset the rotor alignment of the distributor and also reset the ignition timing, adding a lot of extra work to get the car running.

8. Jack up the right side of the car and place a jack stand under it. I always test the safety of the car by pushing hard on it, and shake the car back and fourth, to make sure it is safe on the stand. Slide under the car with the breaker bar, the socket extensions and the 14mm deep socket and back off the exhaust bolts holding the head pipe to the exhaust manifold. It is important to use a quality socket and make sure the socket is fully engaged on the nut. These nutss are soft and are easily stripped of the hex. Removing these exhaust nuts are the most likely cause of any trouble you may encounter on this job. To make sure you get the nuts off it might be worth grinding the champher or lead-in taper off the end of the socket. This champher is intended to make it easier to get the socket over a nut or bolt, but it means you have less hex engagement. So it is better to grind off the tapered end of the socket to get more grip on the exhaust nuts. This usually get them off, but if these nuts are already messed up or really stuck, you may have to go to more drastic means. You can get better access to them by removing charcoal canister assembly (two 10mm bolts and several connectors and hoses). Sometime you can get it loose by heating it with a propane torch. With the extra access, after removing the canister, I have been able to get a sharp chisel on the nut and broke it loose by hammering it at a tangent in the direction to remove the nut. You can also try getting a file on it to put new flats on the nut, or even grinding it off if necessary.

9. There is a bracket that comes from under the exhaust manifold and bolts to the side of the block. There is a single 12mm bolt in this bracket end that is aft of the thermostat housing on the side of the block. Remove the bolt from the side of the block and you can leave the bracket attached to the manifold. It is difficult to see this bolt, but it is not too difficult to get a socket with an extension over it. If the head or manifold has been off the engine before there is a good chance there is no bolt in this bracket since it is easy to forget to install it. If you do not remove this you will be pulling and pulling on the head and you will not be able to break it free even thought all the other bolts are removed.

10. Remove the throttle cable from the carb and bracket (12mm open end wrench required), tuck it out of the way on the driver's side of the engine compartment. Remove the head ground strap off the back of the head. Remove the large vacuum hose that goes to the brake booster. Remove valve cover, three 12mm nuts. Double check all the wires and hoses are removed between the head assembly the block and chassis. The plastic TVSV at the coolant out let is easy to damage, it does not need to be removed but I recommend removing it. If you leave it in place always remember it is there when you have the head off and need move it around or flip it over. I have damaged these costly valves on my own car, so I always remove it, a 19mm open end wrench, or 3/4", removes it.

11. I like to suck up the pooled motor oil with a hand pump, from around the cam shaft, and put it down the two drain back holes. This is not necessary, but all the oil meant to lubricate the cam lobes gets messy when you pull the head off. Now you are ready to remove the 10 head bolts. Use a 12mm socket and extension, just break loose each of the head bolts in the reverse order of the torque sequence for installing the head. Than loosen all the bolts in the same order, this prevents possible warp. Remove all the bolts and get the heavy steel washer from under the bolt heads, you may need the long nose pliers or a magnate to get them all. One time the head bolts were full of corrosion and were very difficult to get out, this is pretty rare but if this happens there is not a lot you can do but force the head bolts all the way out with the breaker bar. This might be caused by not having the head grounded to the chassis separately from the block.

12. Now the head, complete with the carb, intake and exhaust manifold, distributor, and all the vacuum lines, should be able to come off as an assembly. You will have to break loose the head with a larger screw driver or a pry bar. Be careful not to damage the aluminum head face with the pry bar. You can lever edge of the head face or on the upper alternator bracket. Once broken loose lift it up and out, it is helpful to have an assistant help you lift it out of the car since the complete assembly is heavy and awkward to lift, but I have done it alone most of the time. Motor oil and coolant will spill out all over.

Image
Head assembly removed all together.

13. Carefully set the head assembly down on some news papers and allow all the oil and coolant to drain. Use caution when flipping it over to exposed the gasket face on the underside. When you flip it over more oil, antifreeze and even gasoline will drain out of the head assembly. Use blocks of wood to prop up the head assembly securely so you can scrap the old gasket off without damaging any of the components you left on the head assembly, including the distributor.

Image
Cleaning off the old gasket material off the head surface. Be careful not to gouge or scratch the aluminum gasket face.

14. I use a wide wood chisel as a gasket scraper. I have also used a metal plate with a sharp edge, and stiff metal putty knifes as scrapers as well. Be careful not to gouge the aluminum head surface. On really old gaskets it sometimes get tough to scrap it all off, I have used a stiff wire wheel in a drill. If you use this method, do it very carefully, you do not want to scratch up the gasket face on the head. Final cleaning can be done with a fine wire brush, carb cleaner spray and scotch bright pads.

Image
Here is a picture of the damaged head gasket, with the typical failure between the one and two cylinder (the hottest place on the head). This is a pretty severe failure, it was amazing I was able to keep it running up until than (it was barely running on two cylinders). Usually you will be sucking water into the number one cylinder before the gasket degrades this far.

15. Use the same process to clean off the top surface of the block. A wire wheel in a drill will speed this up, and there is little risk of damaging the cast iron block. You can stuff clean shop towels down the cylinder bores to keep the debris out of the cylinders. I use the compressed air gun to blow these debris out, but if you do not have compressed air available it is easier to keep the scrapings out of the cylinders. There is no easy way to drain out all of the coolant from the block I just pick out the larger pieces, and blow out any debris from the water jacket as well.

Image
Scraping the old head gasket off with a wide wood chisel. Notice how clean the top of the number one piston is compared with the other pistons. This is a sure sign of a failed head gasket, the coolant steam cleans the carbon off the piston. With a strong light sometimes you can see this through the spark plug holes when the pistons are at TDC before you pull the head off.

Next installment I will show you how to hand resurface the block surface and the head face, and do a better job than a machine shop.
Last edited by Petros on Wed Dec 22, 2010 6:00 pm, edited 1 time in total.
'87 Tercel 4wd SR5 (current engine swap project)
'84 Tercel 4wd (daily driver, with on going mods)
'92 Mazda MPV 4wd (wife's daily driver)
'85 Tercel 4wd DLX auto(daughter's daily driver)
'01 Honda Civic (other daughter's daily driver)

takza
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Re: How to Replace a Head Gasket: Petros method

Post by takza » Sat Dec 18, 2010 4:04 am

I'm guessing that by placing a jug of water on the passenger floor and CAREFULLY metering water into the intake (PCV opening only)...you could end up with ALL the cylinders looking as good as number 1 in the pic. Think it also cleans the rings. Good idea to use MMOil as a top lube while doing this though. Might take a quart or so? I usually dribble a pint of water into the carb before an oil change....and also flush the oil with a pint of kerosene.
Give a boy a gun-give a biatch a cell phone-and pretty soon you almost got yourself a police state.

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bajabound
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My tercel:: 1985 4WD 6 spd

Re: How to Replace a Head Gasket: Petros method

Post by bajabound » Sat Dec 18, 2010 4:37 pm

Great write-up! now if only I had this before I started working on mine.

I would add a couple notes that I had to check up on - not being a pro at this..

Clean the head really well - on advice from Petros, I stuffed rags and newspapers into the cylinders to prevent head gasket remnants from ending up in the cylinder - it's pretty hard to get the stuff out once it's in there. There's no easy way around this - compressed air blow off helps though.

Don't handle the gasket with dirty hands - also along this note - you don't need any sealant, or spray on the gasket when you replace it. I am willing to admit that I purchased special high temperature head gasket sealant spray because I thought I needed it... you don't need it.

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Petros
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Re: How to Replace a Head Gasket: Petros method

Post by Petros » Mon Dec 20, 2010 7:42 pm

Now the process is about cleaning the head and block and preparing the gasket surfaces. As noted above, you want to try and keep the debris out of the cylinders because they can get caught between the cylinder wall and the piston. Using compressed air to blow all this out before you close it up helps, but it is easier to keep it out from the start by stuffing newspapers or clean shop rags into the bores before you start.

The most important part is to get the gasket surfaces absolutely clean, this you will do last. If you want to scrub the head completely clean, which I rarely do (because of the extra time it takes), you will want to either get a plastic pan (I have used a kitty litter tray, cheap and about the right size, or a disposable foil cooking tray), scrub brush, wire brushes, and scotch-bright pads. Oderless paint thinner, kerosene or automotive solvent makes a good cleaner, along with the carb cleaner spray. You will want to do the final rising with the solvent to get all the grit and dirt out of the area exposed to motor oil under the valve cover. This is again where a compressed air nozzle really helps to blow off all the surfaces, otherwise you just want to use a lot of cleaner spray to make sure you get all the dirt off of it. Any grit left where the motor oil goes (under the valve cover) will get sucked up the oil pump and if it makes it past the filter will grind away at all the important parts of the engine. that is why cleanliness is important in both final leaning and the assembly.

I recommend doing the cleaning in two steps, an initial quick clean and rinse, and than after you are done resurfacing the head and block face, you do the detailed final cleaning just before final assembly.

After you get the old gasket material off the head and block face, you will need to essentially block sand the surfaces. I use a 1 inch think granite tile with a polished surface on it (see the picture below), and wet and dry sand paper. The larger the block the more accurate the resurface, but it can get clumsy to handle if it is too large. You can get a tile at most home supply stores, but a better sourse is places that make granite counter tops, they have piles of broken peices they have to haul to a land fill, they will usually allow you to take all you want. Your piece does not have to be square in shape, it just needs to have a nice polished flat surface. You will need at a min one peice that is about 12" x 6", larger is better. In addition to the small piece, a large flat piece, about 2 or more square feet in size is also useful for doing the head surface if your head is badly warped.

Put either solvent or kerosene on the surface and slide the sanding block over the surface with the 220 grit paper. It works best if you use spray adhesive or tape to hold the sandpaper tight over the block of granite, but I usually just wrap it tightly and hold it on with my hands, but this allows the paper to tear so you use more sand paper. Start with coarse paper, 220 grit is good (but you can also go 150 if the surface needs to be made flat). slide it back and fourth over the block surface pushing down evenly on the back of the block. This will produce a nice flat surface, you can check this by wiping off the top of the block with a rag and carefully inspecting the gasket surface. You must keep sanding until you get a nice even texture, this may take a quite a bit of sanding the first time this has been done. It is especially critical that the block be very flat across the narrow area between the cylinders, this is where the gasket fails and it must be flat to forestall premature gasket failure. The outside edges are not as critical, they only hold water pressure and the gasket can handle that just fine, but typically the top of the block can be several thousandths of an inch out of flat.

Image Piece of granite tile I use to resurface the block and head. Larger is better, but this is what I have, it must be clean, smooth and flat.

You can remove the alignment tubes off the top surface of the block (at the front and back corner head bolt locations). These are for assembly alignment and do not have to be replaced. It is easier to have them removed, but I usually just work around them since they are on the edges of the block surface and perfectly flat here is not important. Removing them can be troublesome, and you can rarely resuse them since they get bent up removing them. It just means you have to carefully hold the gasket as you lower the head on the block, once the head bolts are all in the head and gasket will all be lined up. Note that this method produces a smoother surface than a machine shop, smoother will produce a better seal. The silver coating on the gasket is graphite to allow the head and block to expand at different rates and slide over the gasket surface, if it is smooth there will be less damage to the gasket surface when it heats up. So you want to eliminate all of the old machining marks and gasket texture off the surface and have a nice even mat finish. This is also true of the head surface. Once you have a nice even surface around the tops of the cylinders you can switch over to 330 or 400 grit paper, there is no reason go any to any more fine.

Image Sanding the top of the block, use both hands to get a nice even pressure on the surface (I had to use one hand to take the picture). Notice that the gasket surface is showing an even texture.

You will use the same procedure for the head surface as well. But the aluminum is much softer and it is more important to be careful to keep the surface flat. After you get the old gasket off and you do your first rough cleaning, you can sand the surface a bit and wipe it off to check the flatness of the head. The FSM shows you where to check with a long straight edge and a feeler gauge, the maximum gap under the straight edge is .002". I have found that you can get it much more flat with this method. Putting even pressure on the surface, sand the surface clean and smooth. Again is is especially important to get it flat between the combustion chambers. Using this method you can get it to zero flatness if you use care.

If it is more than about .005 warped, you will want to use the large granite country top I mentioned above. Remove the intake and exhaust manifold and the distributor, because they are in the way. Using spray adhesive glue down two sand paper sheets side by side, and than with solvent or kerosene, slide the whole head across the sand paper. Again pushing down lightly but evenly on the surface. A figure eight patter will take material off quickly, you will want to wipe off the paper and head surface and add more solvent or kerosene so it will not clog up the paper.

Once an even pattern is achieved you will want to switch to pushing across the surface in only one direction. this will prevent getting any rocker on the surface. If you have a lot of warpage you will have to change the paper several times to take the surface down. If you have more than about .010" of warpage, you are likely better off taking the head to a machine shop to have it resurfaced. I have had as much as .020" warp, and it would have taken me sanding it all night, also the cam shaft bore was warped with the head and had to be bored to make it straight. Test if your cam bore is still good by rotating the cam shaft by hand with the rocker shaft removed. It should rotate freely, if not you need a machine shop to rebore the cam bore. If the cam bore is good, you can take a lot off the warped head surface with course sandpaper, but it is a lot of work.

Image Correct technique for resurfacing the head face. My friend Carlin is pushing down evenly on the surface and gliding the sanding block back and fourth over the face of the head. Remember to check the manifold bolts for tightness, the constant expansion and contraction causes them to work loose, they are easy to reach now that the head is off. For badly warped head you will need to strip off the manifolds and use a large piece of granite counter top and coarse wet and dry paper.

This is a good time to inspect the valves. Rought clean the head again and open the valves by hand, and with a strong light look at the valve faces. You can expect to find pitting on the exhaust valves, which you can live with if it is not too bad. But if the exhaust valves have a piece missing or is badly burned and pitted, you should replace them. I will cover how to do that in a later installment, so if your exhaust valves are all good, you may proceed with the final cleaning.

Even when I get the head back from a machine shop, I will still fine sand the surface to eliminate the machine marks and get the surface flat. Even the machine shop can not produce as flat and smooth a surface as this method will. I instructed one friend of mine on how to use this hand process on his honda CRX, he did not have a lot of money to rebuild his engine and did everything he could by hand on it. He decided to pay for having the valves reground (though there is a hand method for that as well), the machine shop owner was skeptical of a "hand job" so he checked it for flatness. The machinist could not even see light coming through under his straight edge, his thinnest feeler gauge would not slide under it either. He asked my friend how he got it so flat because it was better than he could do in his shop. Sometimes careful hand work can produce better results than a large costly resurfacing machine.

Image If you desire the combustion chamber grooves to improve combustion and reduce ping this is how I did it on my head. You want the grooves to lead from the spark plug to the large flat area inside the combustion chamber. Be careful you stay away from the area where the gasket seals the combustion chamber. These grooves allow superheated burning mixture to "jet" into the thin areas and complete burning of the mixture in these areas. It improves power and economy, reduces emissions, and reduces ping. All good reasons to add grooves. Use a triangular or small round file to make the grooves. I do this before I resurface the head face. I have done it on every head I have off the engine, it improves the durability of the head gasket by reducing ping.

I also always add extra cooling holes in the new head gasket. Handle the head carefully with clean hands, hold if from the edges only. Put clean paper on any surface you place it. I have used both a drill and a hole punch set on a block of hard wood to place these holes. Try to make them clean, and stay within the block and head opening areas on the gasket (about 3/8" back from the combustion chamber edge). check and double check you only put them on the side where the ports are located, you do not want any more holes than this because it alters the way the coolant surface circulates. More holes and you may starve other areas of coolant. If the coolant does not circulate forcefully through the hottest places, the coolant will boil away and the head will overheat locally, expand and lift off the gasket and cause failure. That is why the placement of these extra coolant holes is necessary. Toyota should have known better, but I guess they did not want to commit more time to developing this head on their lowest cost entry level car.

Image New coolant holes required on the head gasket. Try and do it neatly, but do not be too worried about it being pretty, it gets ugly inside the water jacket where you can not see it anyway. The size is important, go no larger. Put the gasket in a safe place, back in the package, until you are ready to install it to keep it clean.

Next up is the carefully clean the head and block surfaces, the head bolts and washers, and all the bolt holes.
'87 Tercel 4wd SR5 (current engine swap project)
'84 Tercel 4wd (daily driver, with on going mods)
'92 Mazda MPV 4wd (wife's daily driver)
'85 Tercel 4wd DLX auto(daughter's daily driver)
'01 Honda Civic (other daughter's daily driver)

takza
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Re: How to Replace a Head Gasket: Petros method

Post by takza » Tue Dec 21, 2010 4:37 am

For a head that hasn't been off in a while...what about the valve stem seals? And what's the skinny on hand lapping the valves...better than no valve work at all?
Give a boy a gun-give a biatch a cell phone-and pretty soon you almost got yourself a police state.

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Re: How to Replace a Head Gasket: Petros method

Post by 4wdchico » Tue Dec 21, 2010 8:44 am

takza wrote:For a head that hasn't been off in a while...what about the valve stem seals? And what's the skinny on hand lapping the valves...better than no valve work at all?

Hand lapping is OK as long as you do not over do it. Going overboard with hand lapping will make the valve to seat contact area to wide and will allow too much heat to transfer into the seat from the valve head. A too cold running valve will develop carbon deposits that will eventually build up between the valve and seat and interfere with the previousluy mentioned heat transfer. This usually results in the valve burning.

Back in my days of repairing motorcycles the below linked tools were my preferred method of cutting valve seats. They produce a superior sealing and heat transfer surface on the valve seat.

http://www.cylinderheadsupply.com/neway ... tters.html

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Petros
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Re: How to Replace a Head Gasket: Petros method

Post by Petros » Tue Dec 21, 2010 1:01 pm

We used the Newway valve seat cutting tools in the race shop, the same ones that 4wdchico posted the link if you wanted to purchase. You can do a more accurate and better quality job with these simple hand tools than with costly machine shop tools. But there are also ways this can be done with tools that most home shops have at hand, you just have to get cleaver.

I will cover the head and valves in later postings, for now I want to get the head gasket procedure documented here.
'87 Tercel 4wd SR5 (current engine swap project)
'84 Tercel 4wd (daily driver, with on going mods)
'92 Mazda MPV 4wd (wife's daily driver)
'85 Tercel 4wd DLX auto(daughter's daily driver)
'01 Honda Civic (other daughter's daily driver)

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Re: How to Replace a Head Gasket: Petros method

Post by Petros » Wed Dec 22, 2010 8:10 pm

Final Cleaning Before Assembly

If you have not done so already, scape any carbon off the piston tops with the scraper. Blow the debris out from the edge of the piston and the cylinder wall, rotate the crank to push the pistons up and down to help.

All of the following cleaning steps should be done together until at least you get the head back on the top of the block. This will keep airborne dust and debris from settling on the cleaned parts before they are assembled.

The next important step is to clean out the head bolt holes in the top of the block. These collect motor oil, anti-freeze and gasket debris from the disassemble. It is very important these threaded holes get cleaned out to insure proper bolt tension when you torque them. I use a bore brush about 5/8" dia. (it looks like a skinny bottle brush), most auto parts store have them and they are not very expensive. With each hole you need to fill it with carb cleaner, and thrust the brush down into it, and wind it out as if removing a bolt. Keep a shop rag or paper towel around it to catch all the old oil and debris as it comes out to the surface. Do this several times for each hole, clean the brush in solvent between each incersion. Ideally, but not always necessary, if you have a large metric tape that matches the head bolt thread, you can carefully chase each of the head bolt holes after the initial cleaning. This will clean up the threads if there are any metal burs or corrosion that the brush can not get.

Image
cleaning the head bolt holes with the bore brush, note the use of the paper towel to catch the off scouring.

Clean up any debris out of the cylinder bores, it helps if you rotate the engine one revolution to push all the stuff to the top of the bore, using carb cleaner spray and paper towels. A small amount of compressed air helps (not too much, you do not want to push any debris down deeper), you can also use your breath with a hose to concetrate the blow in the gap between the piston and the cylinder wall. Repeat until the bores comes out clean.

You may want to spray some cleaner down the two oil drain-back holes in the top of the block. this will push an debris down into the oil sump, where you will change the motor oil when you are done with the assembly. This is to eliminate any debris or contamination from the sump that may have gotten down the drain-back holes.

Than wipe off the top of the block with white paper towels and carb cleaner spray, repeat until the paper towels come out white. I have also used Brake parts Cleaner spray, it leaves less residue than carb cleaner. But if you use brake parts cleaner you must keep it off any rubber parts like the timing belt or the hoses, it will break down most rubber compounds not compatible with brake fluid. I have found the carb cleaner spray is good enough. Some books recommend using soap and water on the surface, but I have not found this necessary. Soap will help lift any fine metal particles stuck on the gasket face from the resurfacing, but if you wipe the surface with clean solvent, and the paper towel comes off clean, there is not much else that will come off.

Now final clean each of the head bolt holes with a cleaned brush, fresh solvent and paper towels. Repeat until the white paper towel comes out clean when you wipe the brush off. I have also wound paper towels into a stiff rope and twisted them down into each of the bolt holes to help speed this process.

As a final step on the block, put some clean motor oil on a fresh paper towel and carefully wipe down the inside of the bores to add some lubricant to the rings. Do this very carefully as you do not want to end up with any oil on the gasket face. Once done rotate the engine over several times to spread the oil, and wipe it off the top of the block on the gasket surface as you do this. Do a final clean with solvent and paper towels on the gasket surface one more time to make sure you cleaned up all the motor oil. And do not touch the gasket surface once it is cleaned.

Final Cleaning of the head

Returning to the head, you will want to rinse and blow out the area under the valve cover to get any dirt or debris out of places that circulate motor oil. If you do not have compresses air the spray can of carb cleaner works reasonably well. Than carefully turn the head over (remember all the stuff is still bolted to the head, you do not want to damage it). Than clean off the gasket surface. You should have cleaned all the carbon out of the combustion chambers, and have a smooth and clean head face from the resurfacing. Put some spray cleaner down each of the head bolt bores and run the brush through to get any debris out of the head bolt bores. Than wipe off the face with solvent and paper towels until the paper towels come off clean. Some times the electrical connectors or loose hoses can get in your way when you install the head, so it is good idea to either tuck them in so they are not dangling, or tape them down out of the way.

Image
Resurfaced and cleaned gasket surface on the block. Absolute cleanliness is only required on the gasket surfaces, and the head bolts. Lots of detailed cleaning of all other parts and surfaces, while desirable, adds a lot of time.

Prepare the gasket

Remove the water coolant bypass tube and clean it off. Inspect the o-rings for damage or cracks, if good you can reuse them. If not replace one or both of them. Wipe the o-rings down with a light layer of gasket sealer, the silicone gel type works best, but any type will do. This is not technically necessary, but I have torn new o-rings when they get pushed into their seat, so something slippery will help prevent damage, and also add another level of sealing to the connection. Slip the by-pass tube down into it place in the water pump housing.

Now, with clean hands, put the modified head gasket on top of the cleaned block surface. Again handle the head gasket only by the edges, and make sure you put it on correctly and everything lines up properly. Place the new (or good used) exhaust head pipe gasket on the exhaust pipe flange.

Image
head gasket and by pass tube in place, ready for the head to be "dropped" on top.

Installing the Head

Now, with the assistance of a helper if available, carefully lower the head on to the block. Watch the coolant by-pass tube, it will engage the fitting on the head first, it is also a helpful guide you to line up the head properly. If possible keep an eye on the exhaust head pipe, the manifold bolts are at an angle and do now want to go straight into place. As you lower the head you usually can get the manifold bolts to properly engage the exhuast flange, double check you did not knock the exhaust gasket out of place (this has happened to me several times, if you bolt it up you will crush and crease the new gasket).

Lower the head onto the head gasket, typically you will have to wiggle it a bit at an 1/8" above the gasket to get the alignment lugs to engage. Do this gently, you do not want to damage your new head gasket before you get it assembled. The head should lay down tight to the block without more force than hand pressure. Make sure no loose hoses or electical connectors got clamped between the head and the block, you should have tucked them out of the way before you picked up the head assembly. As you lower the head down, also check that the head pipe is not pushing on the manifold lugs, holding the head up off the block. If the exhaust pipes gives you trouble, you can unbolt the front exhaust pipe mount and put a block of wood between the exhaust pipe and the floor of car to hold it down out of the way. This is rarely necessary, but sometimes it can be a nuisance.

If installing the head on the block sounds difficult, you can practice this several times with out the head gasket and manifold gasket. Than you can see how to coordinate keeping the head surface, the by-pass tube and the exhaust pipe all lined up as you lower the head. I highly recommend a "dry run" if you have never installed a head on a block, leaving the intake/exhaust gasket, carb, distributor all in place make this process a bit clumsy. A practice will give some confidence.

Now that the head is on the block you can take a break or leave it for the night. Everything should stay clean. You will now carefully clean all the head bolts and steel washers.

Preparing the Head Bolts

On these engines you can reuse the head bolts, on many of the modern engines the head bolts are installed until they yield and should be replaced whenever you have to replace a head gasket. But not on these older engines (another reason I like the older engines, they cost less to rebuild). Most performance enthusiasts will replace these one use yielding bolts with hardened steel head bolts, but with this engine, you already get the hardened steel bolts and washers.

Use solvent and a wire brush to clean off the threads of any sealant or corrosion. These threads must be absolutely clean, inspect them carefully under a magnifying glass for damaged threads or any foreign matter. Do a final wash with while paper towels and carb cleaner spray or similar solvent. Solvent soaked paper towels should wipe off the threads and the underside of the bolt heads clean. Some people will number the head bolts when you remove them to get them back into the same holes, but this is totally not necessary. If any of the threads are nicked or damage, use a fine triangular file to clean off the damage areas. A metric tape of the correct size can also be used to chase the threads, but I have never found this necessary. You should have 10 head bolts and steel washer, 5 longer bolts and 5 shorter ones.

You will need some bolt lube for the head bolts to clamp up properly. They sell lubricant in auto parts stores just for the purpose installing bolts to get proper torque clamp-up. You buy it in a small tube and does not cost much, but if you have suitable lubricant already you can use it instead. Any high pressure, high temperature light grease can be used. CV joint lubricant works well, as does graphite axle grease such as used on Ford wheel bearings, and I have seen anti-seize compound used. Do not buy a large container just for the head bolts because but you will not need nearly that much, but I have found this kind of lubricant or anti-seize compound useful in a lot of other places.

Before you install the bolts, you must prepare the cleaned steel washers. These washers are very important for proper clamp up, so do this step properly. With clean hands, put some lube on the top face of the washer (where the underside of the bolt head will touch it) and place each washer on the clean seat at each head bolt hole. These washers have a "top" and a "bottom", they must go in right side up. When they are stamped, the manufacturing process will put a rounded edge on the upper face, and a square edge on the bottom. This will give the bottom side of the washer more area to press against the soft aluminum head. Put them in with the square edge down and the rounded edge up. Double check you have all 10 washer in place before you install the bolts.

Again with clean hands, put some thread lube on the threads of the head bolts, and perhaps a bit on the underside of the bolt head. Not too much, you do not want it squeezing out all over inside gasket face. Just enough to fill the lower half of the threads on the bolt. I use my clean fingers so I can feel the threads, but you can also use a paper towel. Do not allow the lubed bolts to touch anything but the inside of the bolt hole, it will pick up grit and dirt. So lube each bolt and put it down into the bolt hole. Longer bolts go on the left side (carb side) of the head, the shorter bolts go down into right side (spark plug side) of the head. You may have to wiggle the cam shaft back and fourth to get the center right bolt to drop all the way down, use a 14 mm socket on wrench to work it back and fourth until it drops down. Be careful not tot bind it, it could damage or bend the bolt.

Once all the bolts are in place, thread them down until they make snug contact with the washer. Before you tighten the bolts, again make sure the by-pass tube is in place and head is up tight against the block face with the gasket properly in place, you can never be too careful about this. ]

Procedure for Torquing Down the Head

You will now tighten down the bolts in three passes of the torque wrench, in the correct sequence shown below. You always start with one of the center bolts and work your way outward, this is necessary to get proper clamp-up on the gasket. You will want to do this fairly quickly in sequence. Use the 12 mm socket and a medium extension. Tighten to 16 ft-lbs on the first pass, in order. Than use 32 ft-lbs on the second pass, and the final pass at the required 43 ft-lbs. Pull on the wrench handle slowly, holding it evenly in your hand. Be steady and pull sideways, perpendicular to the wrench handle. Use your free hand to steady the other end of the wrench, you want to keep the socket exactly squarely engaged on the bolt head. After I make my final pass I like to go over it one more time to 43 ft-lbs just to make sure I did not miss any and all are properly torqued.

Image
Factory head bolt tightening sequence. Do this exactly as shown for each pass of the torque wrench.

Now your head is finally back installed properly on the engine. Pat your self on the back, if you followed this procedure properly, you very likely got a better installation than they accomplish on the assembly line in the Toyota factory.

Now you have to do the final assembly, which I will cover in the next post. As well as the follow-up care.
'87 Tercel 4wd SR5 (current engine swap project)
'84 Tercel 4wd (daily driver, with on going mods)
'92 Mazda MPV 4wd (wife's daily driver)
'85 Tercel 4wd DLX auto(daughter's daily driver)
'01 Honda Civic (other daughter's daily driver)

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Petros
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Re: How to Replace a Head Gasket: Petros method

Post by Petros » Tue Dec 28, 2010 7:37 pm

The final assembly steps

This is a good time to drain the old engine oil, it should be done to get any debris that may have gotten down the oil drain-back passages and if there is any coolant in the motor oil (the oil will look like a chocolate milk shake). Remove the drain plug and allow the old oil to drain out as you do the following assembly steps. After it is drained, if you want to make sure you clean out any debris from the oil drain back galleys, before you put the drain plug back in the oil pan, spray or drain solvent down the two oil drain back holes in the head, with the drain plug still out. One of the drain back passages is in front of the distributor, and the other up front on the right side. This will also help wash out any sludge or debris from your oil pan as well. Allow enough time for all the solvent to drain and than install the drain plug and the new oil filter.

1. Install the timing belt: set the crank at top dead center by aligning the front pulley notch with the "0" mark on the timing belt cover, turn the cam pulley until it the hole in one of the spokes lines up with the point marker on the front of the head (you should see the point through the hole, see the diagram from the FSM below). Slip the belt over the pulley and release the tensioner/idler mount bolt to allow the spring to tension the belt. Add a bit more tension by pushing on it since the spring does not put quite enough tension by itself on the belt (especially if you have a new belt, it will relax a bit after it warms up). The belt should deflect about 1/4" with 4.4 lbs load on the long (right side) leg of the belt when properly tightened. Tighten the tensioner bolt on the idler to 27 ft-lbs. Now turn over the engine by the front pulley by hand full two rotations. When the lower pulley mark reaches zero and double check the alignment of the cam pulley is still correct. This will also tell you if something is binding or misaligned, this is a simple step than only takes a minute, but you would not believe how many experienced mechanics skip this step and create a lot of expensive headaches later. Sometimes you could be off by a tooth, and this is just to double check. If everything is still aligned, you can replace the front timing cover, and the water pump pulley. Note if you left the distributor in place your spark timing should still be correct and does not need to be checked. Note: if you are going to replace the cam shaft with a performance regrind (like the one from Delta Cams of Tacoma WA), this is a good time to do it since the timing belt is off and the came is exposed. It is an easy process of removing the cam bearing caps, replacing the cam after swapping over the pulley and distributor gear, and replacing the bearing caps. Make absolutely certain the bearing caps are installed with the arrow pointing forward and in the correct order (they are numbered front to back), torqued to the correct value. This is also a good time to install a new cam seal since it will be off anyway. Lubricate the lip of the seal with some light grease or motor oil, and you can also apply some sealant to the seat to anchor the new seal into place.

Image
Correct timing belt alignment. Note that you do not need to line up any marks on the belt.

2. Install all the vacuum lines, the fuel hose lines, the electrical connectors on the carb and distributor, the head ground strap, and the upper radiator hose. Install the alternator top mount and the fan belt, tension the fan belt before tightening the alternator upper bolt. Double check the radiator drain plug is installed and tight (do not over tighten it, it is plastic and will easily break-put gasket sealer on the rubber washer if you want ta good seal without too much plug tension). Double check the oil drain plug is in and tight, and the oil filter is installed.

3. Double check that the exhaust head pipe gasket is still in place and in correct alignment. sometimes during installation this gets misaligned and you want to make sure it is in place before you tighten the nuts down. If you want to make this easier to get off next time put anti-seize compound on the exhaust manifold studs and than tighten the nuts down, clamping up the exhaust pipe gasket. You can usually snug them down from the engine compartment using a 14mm open end wrench, but to get an accurate and tight torquing of the exhaust bolts, they need to be tightened from below using about 16" of socket extension. Tighten to 46 ft-lb. Install the forward exhaust pipe mount if you removed it earlier, now you can lower the car back down off the jack stand onto the ground.

4. Now is a good time to check your valve clearances, though these should not have changed if you did not remove them, but it is a good opportunity to check them. For the cold engine 0.007" intake clearance, and .011" exhaust clearance. Since your camshaft is dry from the cleaning, some kind of cam lube should be added to the both ends of the rocker shaft. A light graphite grease can be used, the left over thread lube used on the head bolts is also good. Make sure you also lube the fuel pump eccentric and the distributor gear as well. Now pour the new motor oil all over the valve train, rocker shaft, cam shaft and fill all the oil catchment areas on top of the head to lubricate valve train.

5. Clean the rocker cover, inspect the gasket for damage. Usually this rubber gasket can be reused if it is undamaged and still pliable. If is its broken or brittle, it will not seal and will always leak. I have reused stiff and broken rocker cover gaskets, but I covered them Permatex Form-A-Gasket. Since the valve cover is prone to leak anyway I usually wipe off the gasket and the head surface where it seals good, and install gasket sealer. Make sure the half round rubber plug is in place at the back of the head (if not, clean it, cover in sealant, and install it). Than install the rocker cover and snug down the three 12mm nuts with the rubber washers under them. Sealant can also be applied to the rubber washers to prevent oil leaks. Install the two 10mm bolts through the front timing belt cover into the valve cover. It has become a popular fad to leave this timing cover off the engine to expose your timing belt and cam pulley, do not do this-it is very foolish. Especially, as I have to, you drive on unpaved surfaces or gravel roads at all; gravel and stones get thrown up into the engine compartment and it will get under the timing belts and chew it up. Not only will it cut and damage the belt, it will errode away soft cam pulley and likely get behind the crank pulley and damage the front main seal. It is also dangerous if you ever work on the engine while it is running, like when you are setting the timing, you can also get tools, fingers, hair, clothes, etc caught in it.

6. Check your oil level and add to top it up. Install the throttle cable, than install the air filter assembly (remember to connect the vacuum line to the underside of the filter housing). Install the electrical connectors to the temp senders on the front of the head and on the coolant outlet. Fill the radiator with the saved coolant, or install new coolant and distilled water. NEVER use tap water in the radiator, it will scale up the inside of the radiator and make it worthless. Use only filtered or pure bottled water and antifreeze. As a total cheapskate when it comes to saving costs, trust me that using bottled water in the radiator is a lot cheaper than replacing the radiator. If you removed the spark plugs, install them now and connect the spark plug wires.

7. Now you should be ready to start the engine. If you removed the distributor you will have to follow the installation procedure found elsewhere in this forum to get it aligned and timed close enough to allow it to start. Double check the oil level and the radiator (this too is easy step to do and could save you a lot of trouble if in all the effort you forgot to put in coolant or oil). It will take about 30 seconds of cranking to get the fuel up into the carburator for it to start, so crank it and than give it several pumps of the throttle (not too many, you do not want to flood it). You can also put a short burst of starter spray in the intake to get to run enough to get the fuel flowing, but this is rarely necessary. As you are cranking it watch the oil light on the dash, it should go off while you are cranking it or right after. Remember that all the oil galleys in the head are empty and until they fill the oil pressure light will not turn off. If after 30 seconds of running the oil pressure light does not go off, turn off the engine and double check the oil level and the sender wire is connected. Also keep an eye on the water temp as it warms up. It should stablize at about half way.

8. The first order of business is to set the idle speed after it has warmed up. Double check the tension on the throttle cable that it is not too tight (allows the throttle to return to its stop). You also might double check there are no vacuum leaks, as many times as I have done this job I still sometimes miss a vac line that is hanging loose in the engine bay. Also during this first run look for water leaks at the hoses and the water pump by-pass tube, and oil leaks at the oil filter. If you need to you can check the spark timing, remove and cap the distributor vac lines, check your idle is about 800 rpms and set the timing to 10 deg BTDC. Than remember to put the vac advance lines back on the distributor. Keep checking the engine temp on the dash all the while the car is idling, it is not unusual to have large air bubbles caught in the engine when you fill the radiator after the engine has been apart. IF it is above the half way mark on the temp gauge, turn off the engine and let it cool off a bit, and than top up the coolant and motor oil if necessary, and than complete the timing and other checks. Even if it does not run hot, after this first idling run time, you must check both the motor oil and coolant levels, and top up if necessary.

Note: The first time you run the engine after you had it apart it will smoke is strange places, and also the exhaust pipe will give you a lot of blue smoke. This is from the ring lubricant you put in the cylinders and all the handling, spilled oil and sealant you put all over the engine. This is totally normal, it will go away after your first running of the engine.

Now you are ready for your first test drive. Keep an eye on that temp gauge, and take it easy on the first drive. Everything should be working normally, and indeed, with the modifications I outlined above, it should be running as good, if not better, than it ever has.

Follow up Care

Older design head gaskets require re-torquing the head bolts after about 500 miles of driving, and it must be done or the gaskets loosens up and will fail. The Toyota Tercel head gasket is designed to not require re-torquing. I have done it anyway, but sometimes I have skipped it. If you want to just double check and make sure you have a solid head gasket installation, re-torquing the head can be done. I usually do it on mine. This requires you to remove the air cleaner assembly, the valve cover and than with your 12 mm socket on your torque wrench re-tighten all the head bolts. There is a required technique: In the same order of the tightening sequence, first break the head bolt free with a short 1/8 of a turn backwards (or less if you hear the bolt "pop" free in the backward rotation), and than pull forward to the required 43 fl-lbs. Repeat this procedure for all 10 head bolts in the proper sequence.

This is also a good time to check your valve clearances since the valve cover is off. This should not change, but if you had your valves reground when the head was off than it should be checked again. The seats may wear-in a bit faster on the first few hundred miles of driving after any valve work, so they should be re-checked. Again cold: .007" intake valve stem clearance, .011" exhaust valve stem clearance. I have had better luck when the engine is warm to get the valves quiet, so if I drove the car into the garage to do the head re-torquing, I will set the valve clearance first wile I am waiting for it to cool. Hot engine: intake clearance 0.008" intake and exhaust clearance 0.012".

Check your oil and coolant levels and you should be good to go another 100,000 miles or more on your newly installed head gasket. The head gasket is still very sensitive to overheating, so always watch your coolant level and your temp gauge. But the modifications done as outlined above should make it more durable, run better and may even improve the fuel economy and performance a little bit. It will almost certainly run smoother if you were driving with a bad or leaking head gasket.

Next up

This section stands alone as a process for replacing the head gasket only. Eventually when I get the time I will add another section on resurfacing the valves, polishing the ports and combustion chambers, and balancing the combustion chambers as well as a few other performance tweaks to the head.
'87 Tercel 4wd SR5 (current engine swap project)
'84 Tercel 4wd (daily driver, with on going mods)
'92 Mazda MPV 4wd (wife's daily driver)
'85 Tercel 4wd DLX auto(daughter's daily driver)
'01 Honda Civic (other daughter's daily driver)

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Re: How to Replace a Head Gasket: Petros method

Post by ARCHINSTL » Tue Dec 28, 2010 9:43 pm

We stand in awe.
Thank you.
T4WD augury?
Oh, do not ask, 'What is it?' Let us go and make our visit.
T.S. Eliot - "The Love Song of J. Alfred Prufrock"
Now and then we had a hope that, if we lived and were good, God would permit us to be pirates.
Mark Twain

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Petros
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Damaged Exhaust valves

Post by Petros » Thu Dec 30, 2010 7:20 pm

I had list member Ozarksjl send me this picture of his head with a damaged exhaust valve. I thought it was worth posting here to add information about this kind of event. You would use this same procedure to remove and install the head for any reason, including a complete rebuild of the engine, or as in this case to replace a damaged exhaust valve.

Image
Overheated exhaust valve damage, common when running the factory 5 deg BTDC spark timing. Note the different combustion chamber shape on this stock head vs. the combustion chamber shape on pictures of my head above.

When you run the factory ignition timing you run the risk of exhaust valve damage like this. I have even seen the whole head of the exhaust valve melt and break off and embed itself into the top of the piston (doing major damage to the engine and head). I have had this same kind of damage as pictured happen to mine several times, until I replaced all of the exhaust valves with new ones and set my spark timing at 10 deg BTDC. The valves get heat damaged and once this occurs, all of them should be replaced. The others will soon follow, the number one cylinder exhaust valve will almost always go first, it is the hottest combustion chamber (it is where the hottest water leaves the head on its way to the radiator), but it is only a matter of time with the rest.

So if you have to replace an exhaust valve, replace all of them. If you are rebuilding the whole head, replace all of the exhaust valves. Than when you get your engine back together, set your timing at 10 deg BTDC, rather than the factory 5 deg, this will not only allow the exhaust valves to run cooler, but it will improve your fuel economy a little, and improve the power output. If you live in a state that requires yearly or biannual emissions testing, remember to set it back to 5 deg for the test, and than return it to 10 deg or you risk damaging the valves again.

The intake valves can be reground and reused, they do not suffer the same kind of heat damage as the exhaust. So if you are overhauling the whole head with a resurface, and reground valves and seats, replace the exhaust valves. They do not cost much and well worth it. when you regrind the face of the valve it makes it thinner and more likely to suffer heat damage as shown in the picture. Also, have the guides checked for wear, replace as necessary, and have the shop install all new valve guide seals.

And of course you use the same head installation procedure as outlined above, including the gasket modification.
'87 Tercel 4wd SR5 (current engine swap project)
'84 Tercel 4wd (daily driver, with on going mods)
'92 Mazda MPV 4wd (wife's daily driver)
'85 Tercel 4wd DLX auto(daughter's daily driver)
'01 Honda Civic (other daughter's daily driver)

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Re: How to Replace a Head Gasket: Petros method

Post by TURTCEL » Sat Jan 12, 2013 11:14 pm

Hey Petros,

With the improved head gasket set up that you do by adding the extra ports in the gasket for the water jackets do you notice that the temp guage reads cooler or is it not noticeable to that degree? I know it greatly improve the head cooling to certain areas but just wondering if I would be able to see it on the guage.

I will definitely be doing the gasket upgrades when it comes time...hopefully never.


Peace
1985 Tercel 4wd SR5 Wagon, WEBER Carb, Brown (TURTCEL)
1988 Corolla DLX All-Trac Wagon, 4 speed AT, Silver (Wife's new car)
1993 Ford Escort Wagon LX, 5 Speed, Smurf Blue (Smurfette)...selling

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Petros
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Re: How to Replace a Head Gasket: Petros method

Post by Petros » Mon Jan 14, 2013 10:52 am

the temp gauge reads it at the outlet where it would be a mixed average, not likely it would be noticeable. the mod results in more even head cooling. I think the age and quality of the thermostat and radiator would have more to do with that.
'87 Tercel 4wd SR5 (current engine swap project)
'84 Tercel 4wd (daily driver, with on going mods)
'92 Mazda MPV 4wd (wife's daily driver)
'85 Tercel 4wd DLX auto(daughter's daily driver)
'01 Honda Civic (other daughter's daily driver)

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Re: How to Replace a Head Gasket: Petros method

Post by Petros » Thu Apr 10, 2014 6:27 pm

I had a recent experience I want to share here since it is relevant to the thread. I replaced my modified 3ac engine last October 2013 with a fresh rebuilt 4ac, it was a standard overhaul with over-sized (but low compression) pistons, new valves, bearings, seals, etc. but I enlarged the ports and installed a Delta street grind cam, and used my lightened flywheel, but stayed with the factory compression except for what the overbore and resurface added. I toqured the head at 44 ft lb per the 4ac manual and used all of the same procedures. the water circulation through the head gasket is also slightly different than the 3ac which I hoped would help the uneven cooling condition that 3ac suffers from, and did not feel it necessary to alter the gasket as much.

The newer head gaskets in general do not need to be retorqued per the FSM, this was not the case in the past. All of the old cars from the 50's, 60's and 70's always had to have the head gasket retorqued after 500 miles of run time. Once I did not do this on an old Dastun 1600 (sports car), but let it go to 700 miles, and found the head gasket blew so I had to replace it again. so it was real important to retorque the head within 500 miles of installation. Also when I worked for the Nissan racing team we had all metal head gaskets and steel o-rings for the turbo engine and would always test run the engine on the dyno for several hours, and than retorqued the head on that as well. But all of the production head gaskets since the late seventies are designed not to be retoqured, I suppose an innovation to prevent warranty work on new cars. Sometimes I would retorque them after a few hundred miles, sometimes not, depending how busy I was when I uses the newer headgasket designs. I have had any issues I can attribute to not retorquing, but mostly I did it out of not trusting this "new fangled" technology head gasket.

Anyway, back to my 4ac, all torqued down per FSM in October. I have been driving it almost daily except for the 2 week vacation in November. Generally running strong with no issues, no oil consumption (a rare thing with any car I own!), and no leaks. about a month ago I notice the temp climbing up a bit on steep hills (Like the one leading up to our house), so I checked the coolant level and it was about 2-3 cups low, so I topped it up. several weeks later the same thing happened, so it was looking like the head gasket was leaking already. I could not think of anything that would have caused this since I rarely even rev it high, and generally try to save fuel so I drive very lightly on it. This Tuesday, April 8 I had a lot of driving to do all over the Puget Sound area, so I topped up the coolant at about 9:30am, hoping it would not blow all at once. Usually you can drive on a leaky head gasket, but as some point the gasket just breaks down and you lose compression and it blows all the water out all at once, and you are stuck. By about 4 pm that day it was running hot again and I had to pull over and top up the water already, it took over a quart. This now was using coolant an an alarming rate, and a new head gasket was almost certainly in my near future.

When I got back to my office I ordered another head gasket and hoped my head gasket would stay together long enough for the new one to arrive (I got it from rockauto shipped to me for about $15, Autozone wanted $37!!!). An idea occurred to me to check the head bolts and perhaps forestall the leaking. So yesterday morning I pulled the valve cover off and retorqued the head. The normal process I use is to back the bolt off until it breaks free (usually about 1/8th of a turn), and I can see on my torque wrench the torque it takes to break the bolt free. Usually if I set them at 44 ft-lbs, it will break free about there too, plus or minus about 5 ft-lbs. All the head bolts but one would break free at only 24-25 ft lbs!!!! Some how they were way under toqured, from perhaps the head gasket compressing, bolt stretch or something.

The gasket I used was not my normal Fel-Pro, but I think ITD or something like that, it came in the kit my machine shop ordered. I do not know how good they are, but they are not particularly bad brand, are used by a lot of private repair shops. Anyway, with all retorqued yesterday, coolant topped up, drove it for a day, and this morning at about 10 am I check coolant level. I had not lost any coolant at all. So I do not know if I solved the problem, or if the head gasket is now compromised and I may have to do it later. But the coolant loss has been considerably slowed for now.

The point of this story is that it probably would not harm anything to always retroque the head bolts 400-500 miles after you have replaced it or rebuilt the engine. It may not need it, but it could save you a lot of trouble to if you do and like me, put about 5000 miles on it, loose coolant and risk damaging the new head gasket, before you retorque it. So retorque the head bolts, and the intake and exhaust manifold bolts while you are at it.

Some times the old ways still work best.
'87 Tercel 4wd SR5 (current engine swap project)
'84 Tercel 4wd (daily driver, with on going mods)
'92 Mazda MPV 4wd (wife's daily driver)
'85 Tercel 4wd DLX auto(daughter's daily driver)
'01 Honda Civic (other daughter's daily driver)

Tercel-Joe
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Posts: 3
Joined: Wed May 23, 2012 1:54 pm
My tercel:: 1986

Re: How to Replace a Head Gasket: Petros method

Post by Tercel-Joe » Mon Jan 05, 2015 9:44 am

Thank you for this post. It was a great help in my recent valve job. I had a burnt valve like the one in the picture. Everything is going back together well. Stumbled a little bit because I had the timing 180 degrees out. Waiting for a new radiator so I can warm the car up fully and finish the job.
Sincerely,
Joe
1986 Tercel 4wd

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