head gasket question

simon84 · Post by **simon84** » Tue Nov 27, 2007 1:19 pm

A question about heads and gaskets.
I replaced the head gasket on my 87 sr5 since it was pumping pressure and gas vapour through the rad when running.
Now it's running a little better, but once hot there is a fair bit of pressure in the oil (oil splutters out the oil filler cap when open). Also see a bit of milky stuff in the oil.
So I'm thinking that it could be a warped head and I should redo the head gasket and get the head machined this time.
Any other possibilities?
I'd like to get it right this time.
I've ordered the weber so I'd like to get it all done right when that comes.
thx

keith · Post by **keith** » Tue Nov 27, 2007 5:42 pm

If you've put less than 600 miles on it since the replacement, you migh try retorquing the head gasket first. If that doesn't work, then, yes, get the head checked for flatness.

Post by **Petros** » Tue Nov 27, 2007 7:35 pm

You should never replace a head gasket without checking the head for flatness, ever. Most shops ALWAYS do a crack check (dye penetrant inspection or pressure check) and resurface the head no matter what the reason for the gasket failure. Toyotas are not prone to cracking so you most likely can skip the crack check unless you suspect it might be cracked.

This is especially true of aluminum heads, they warp a lot easier than cast iron.

There is a procedure that you must follow or your risk of the new gasket failing is quite high.

1) After making sure the head is flat, I use a piece of polished granite tile as a sanding block, and 800 grit sand paper. I go over the top of the block until it is smooth and clean. You can tell the high places if any on the block this way. If your head is not too badly warped you can also use this method to make it flat, but it is slow going. Use mild solvent with the sand paper.

2) clean out all of the bolt holes with a mini "bottle brush" and solvent. Blow clean with compressed air if available. Then final clean the top of the block, the bolts, the bolt holes and the head surface with brake parts cleaner. Use white paper towels and keep at it until they come up clean. Test thread each of the bolts into the each of the holes to check for burrs or grit, they should thread in and out smoothly with out hanging up. If there are any burrs you need to chase the threads in both the hole and the bolts with the correct size tap and die to clean up and damaged threads. Blow out any metal shavings or dirt.

3) Put assembly lube on the bolt threads and washers. Wheel bearing grease works for this or you can buy the special lube made for this at an auto parts store (one small envelope does not cost much). Do not get any grease on the gasket or gasket surfaces.

4) mate head and block with the gasket in between carefully, do not forget the little by pass tube at the water pump. Place the head bolts and washers and tighten per the manual sequence. It is important to follow this sequence. And tighten in several passes until you reach the specified torque.

With this procedure you will should never have a bad head gasket installation. Most modern head gaskets do not need re-torquing for the life of the engine.

Good luck.

83toybeater · Post by **83toybeater** » Tue Nov 27, 2007 7:40 pm

oil is gona come out the oil cap, its ohc motor and they all do that. its normal spashing. now if it wasnt i would be worried. hows the oil look when you drain it?

is coolant dissapering?
is oil level going up?

Post by **Petros** » Tue Nov 27, 2007 7:50 pm

You remind me, if you have a lot of pressure in the crank case it likely is from too much blow-by in the rings. This could cause a lot of oil to blow out of the filler cap when you take it off when it is running. This is not uncommon on high mileage engines.

Before you take the engine apart do a compression check, and then add a squirt of oil in each cyl and do it again. If the rings are worn out the compression test will go up a lot. If valves are worn out it will just be low (less than 100 psi) and will not go up much with the addition of oil.

If the valves are suspect you can have them reground when you have the head resurfaced. Or you can do the low-budget valve job and just lap them in with lapping compound until all of the pits are gone. You will need a valve spring compressor (rent or borrow one).

Pulling the engine is a major job but it is the only way to replace the rings. There are some products that you can try that are supposed to de-gunk the rings to help them seal better, and other products to add to the oil to reduce the blow-by. This might allow you to but off doing a full rebuild.

takza · Post by **takza** » Wed Nov 28, 2007 5:04 am

Petros wrote:3) Put assembly lube on the bolt threads and washers. Wheel bearing grease works for this or you can buy the special lube made for this at an auto parts store (one small envelope does not cost much). Do not get any grease on the gasket or gasket surfaces.

I've always thought that using lube on the head bolt threads threw off the torque readings too much....that the threads should be clean but dry.

I use grease a lot of other places...espec where there's any chance of rust...but I watch the torque used due to the grease.

simon84 · Post by **simon84** » Wed Nov 28, 2007 9:20 am

The main reason that the pressure in the oil is an issue is that it seems normal at start up but after running for a while it is noticabley increased. There seems to be an antifreeze smell in there too.
I think I'll try retorking the bolts first, but I assume that it needs the head machining.
Thanks for all the tips.

Post by **Petros** » Wed Nov 28, 2007 12:57 pm

putting head bolts in dry runs the risk of uneven torquing. Some might hang up more than others. The lube on the threads makes for more reliable and even torquing. I do not know of any performance builder that does not use assembly lube on the head bolts, main and rod bearings, and anywhere else proper torque is essential. Even if the lube gives you slightly higher torque, they will be more even which is more important than absolute torque value.

Mac · Post by **Mac** » Wed Nov 28, 2007 7:59 pm

I used ARP bolt lube (assembely lube is not the same as this stuff!) when i rebuilt my girlfriends escort engine, they claim it can take pressures up to 500,000PSI (amont of force that will need to be exerted on the lube untill it squeezes out & away)

anyways, i lubed up all the bolts, and its still in one piece, they say to use a liberal amount, but to use the same amount on each bolt. it also works as an assembly lube, so if any extra gets on a bearing or journal, its not going to be a problem.

as far as torque readings, they say you can reduce the amount of torque recommended by 10-11%, I torqued it all the same anyways, but if your worried about stretching bolts beyond their yield you could go with the minimum recommended torque settings.

oh yeah, it stains clothing really good and is a little difficult to clean off of surfaces (but nothing some brake clean and rag can't take care of)

simon84 · Post by **simon84** » Sun Dec 16, 2007 11:58 pm

So I tried retorking the head bolts and upped the tork to about 50 from the recommended 43.
Only done short drives and seems ok. I'll go a bit longer tomorrow.

2 other issues going on that I'm a bit stumped on:
the brake light is on and the brakes work fine. Fluid level seems ok, could be topped up but not really low. ANy suggestions?
Also still don;t have any detectable heat in the car.
I do need to reinstall the rad fan switch sensor thingy. The rad fan runs all the time right now, but I'm thinking I should still have some heat.

takza · Post by **takza** » Mon Dec 17, 2007 3:26 am

I'd definitely use some stop leak in the antifreeze...maybe Bar's Leak? If your oil pressure was going up...that means exhaust into the oil...not good at all...not to mention coolant in the oil. New oil and filter needed?

Brake light could be the switch at the e-brake?

My OEM fan would run all the time due to some wiring snafu in the wire bundle over on the pass side of the radiator...I'd move that around some and the problem would go away until the next time it got bumped.

I eventually put in a mechanical adjustable fan switch by putting the bulb inside the top rad hose near the thermostat and mounting the switch on the pass shock tower. I intend to remove the bulb and coat it with RTV gasket goop to protect some from corrosion.

These engines are set up to not have the fan run except in summer usually and not even then when in traffic? They barely circulate thru the rad in winter?

This engine tales forever to warm up from idle...you need to drive it around and then work on this kind of thing.

I'd pull the fuse for the fan and see what kind of coolant circulation you are getting. Feel the hoses for heat.

No heat would mean either a stuck thermostat or your heater valve is not working or adjusted right...you can try putting some WD40 on it and turning it by hand to get it open...or just replace it with a straight tube for winter?

simon84 · Post by **simon84** » Mon Dec 17, 2007 1:49 pm

Topped up the brake fluid and the brake light went off.
Picked up a thermostat today, so hopefully that helps with the temp.
Drove around a bit and on the highway for 20 min and the head gasket seems to be holding.