Engine Rebuild Questions!

[4wdEconoBox]

Ok, so I've finally saved up the money to get all of the parts for the engine rebuild. Does anyone have any pointers, tips, advice or opinions on rebuilding the 3AC? Are there any parts that I should order that are kind of "not the norm"? Like when it comes to valve/head related items, because, as of right now, I've got intake and exhaust valves, valve guides, valve seats, and valve stems in my cart, do I have to have all of these, or should I not get them?
As far as everything else, I've got a complete gasket set, main and rod bearings, piston rings, oil pump, fuel pump, timing belt kit, 2 cheap Wix oil filter and 1 expensive Wix oil filter, and a clutch kit. Is there anything that I'm forgetting? I've got all of that in my car and ready to be ordered, I just want to make sure that there's nothing else I'm overlooking before I order everything.

[Petros]

some people also replace the oil pump, that is somewhat costly, so I would not do it unless your oil pump is trashed. That would only happen if your bearings were giving up metal to the oil and it was getting sucked up by the pump, or if it was always run with really dirty motor oil and the fine grit ground away the internal gears. Some people replace them as a matter of course, I like to pull the back cover off of them (usually needs an impact screw driver) and inspect the housing and gears for wear. If they are within specs I will clean it and reuse it.

Follow the manual procedure for the lower end. I would buy over-sized piston and rings and have the cylinders overbored, the cylinders do not wear evenly and even with new pistons, if the wear is excessive, you will get piston slap and eventual piston failure from too much clearance (I have seen it happen several times). It adds cost, but will give you a better rebuild that will likely last for several hundred thousand miles.

Make sure you clean everything really good, use assembly lube on the moving parts, use a good calibrated torque wrench on the rod and crank bearing cap bolts, and on the head. Go read my thread on replacing the head gasket over in the repair guild section for the critical head gasket installation, and some suggested medications.

You should not need new valve seats, those can be reground, usually the same with the intake valves, though new ones are not a bad idea either. You should use only new exhaust valves, the high heat often damages them and they should not be reused. Valve guides do not always need to be replaced, but if you have an engine that was neglected, or has known bad guides, new ones are not a bad idea (and they are not very costly). You will have to have a machine shop install the guides, and resurface the head face, as well as regrind the valve seats.
You might also want to have the valve springs tested, usually they are fine to reuse, but occasionally one or two will be weak and should be replaced. You can set up a simple jig to using your bath room scale to test them yourself, or just let the machine shop test them.

Good luck.

[4wdEconoBox]

Yeah, I had planned on replacing the oil pump, just out of precaution, its only $51 from rockauto, so I figured why not give it a shot.

How bad would it be if I just kept the stock pistons that were already in it and honed the cylinders at home and just put standard rings in it? would it last or just be a waste of time trying to use the stock pistons without oversizing? I didn't plan for buying pistons, and I don't really have the funds to get them at the moment. And I'm really needing this car running as soon as possible, ya know?

And alright, I removed valve seats and intake valves from my cart. And alright, I'll probably get the machine shop to test the valve springs, just so I'll know for sure. I think I am going to go ahead and order the valve guides, just for safety. And I've actually got your thread bookmarked on the head gasket installation process haha.

What about head bolts? I think I read somewhere that they do not need replaced but I just want to make sure.

Thanks!

[irowiki]

If you are going to do a rebuild, you don't want to cheap out. Standard size pistons on rockauto for $7.50 each!

If you have not bought anything yet, the master rebuild kits tend to be a good deal.

[4wdEconoBox]

Yeah thats true, will the ones for $7.50 still work even though they say there for a 1AC? And if I went with standard sized pistons and rings, would I be fine with just honing it and not boring it out and putting in oversized pistons and bearings?

And I seen those, but I compared that to piecing everything together and I come out a good bit cheaper piecing it together because of some of the deals I can get haha. I'm hoping that everything will be the same quality!

Edit: Nevermind, I didn't know that the master kit came with the full gasket set, I'm about to see how much it is now and compare them again!

[irowiki]

1AC and the 3AC used the same pistons, the blocks were the same.

Provided your clearances are fine, standard pistons would work. unless there is a lot of wear. What miles?

[4wdEconoBox]

It has 244,000 miles, and I just re-did the price comparison and I can get the master rebuild kit and everything else for $5 more than piecing it together, plus everything will get here about 5 days earlier than piecing it together! So I think I'll be getting the master rebuild kit and bore it .020" oversized, so that way it'll be done good and done right! Would .020" oversized be good, or would .040" be better?

[Petros]

I would not use standard size pistons, I replaced the pistons once with standard size, and honed the cylinders. I check the size of the bore, seemed to be at the high end of the clearance range but not bad, but did not want to spend any more money on it.

less than three months later the new piston skirt collapsed because of piston slap. that is where the clearance is large and the piston actually rattles around in the boar as it runs. I could hear a harmonic where it got loud and less loud as the rpms increased, kind of a loose rattling sound. Despite the new pistons and rings, and clean motor oil, too much clearance caused fatigue of the metal and the skirt broke off one piston. Remarkably it still ran, smoked oil like crazy and made a loud "clack, clack" sound. I took the head off and notice one piston would flop back and fourth about 30 degrees in the bore. I took it out and one skirt was missing (just the piston crown was on the end of the connecting rod), ripped the rings out, damaged the bore, the broken rings and skirt were in the oil pan.

If there is any wear in the bores it is a waste of time and money to not over boar and used oversized pistons and rings. since I had to rebuild the motor anyway, and the larger oversize cost the same, I bought a set of .040" oversize piston and rings. they do not cost that much. the boring will add cost of course, about $100 or so. Get the pistons first so they can match bore to the size of the pistons, they should have exactly the specified 0.003" clearance at the skirt. (double check that clearance with the FSM, that is what I recall it being, but it was a long time ago).

You can only reuse the bores if you are within the factory specs, have the machine shop measure it for you. If it needs to be bored and new pistons, do it. It is really bad if you have too much wear in the bores.

An engine with that many miles on it almost certainly has wear in the bores, tiny grit in the oil acts like a fine hone compound and wears away the cylinder wall each time that piston goes up and down the cylinder. My engine only had 188k miles on it, the previous owner clearly did not change the oil very often and worn cylinders were the results.

I learned the hard way on that, and I will not do it again. I strongly advise you not to use the old pistons and get it overbored.

The .020 over bore is fine, you can go another .020" to .040 later if you rebuild it again after another 200k miles. You get slightly more power out of the larger over bore (both more displacement and a slightly higher compression ratio), but it is not much. Also, there was as service bulletin out warning about 0.04" over bore could cut into the water jacket because of some defective castings that had thin cylinder walls in the early engines. I have never heard of this being a problem, and Synth overboared his 3ac to 4ac size pistons (to 1600cc!), so I doubt it is an issue, but going .020" will give you that much less risk of it being a problem. the solution was to sleeve the engine cylinders (very costly) or replace the block (not as costly).

[xirdneh]

i think i'll add my bit to this
a guy gave me an engine that had over 250,000 miles on it
it was a filthy mess with oil caked all over it
i decided re-ring it and not do anything else unless it was obvious
i had the head tested at the local machine shop and they said it was good (i did not replace valve stem seals)
i used plastigage to see if the bearings were within tolerance and they all were good (just barely)
i honed the cylinders with a drill and the three stones style honer and some honing oil (like they use for knife sharpening stones)
you have to do that or the rings will not seat
the cost of rings, a few gaskets and head gasket was around 150.00 (that was around 2004)
the engine is still running well and has been close to trouble free. (had to replace head gasket last fall)

one last thing
i broke in the rings by driving the car hard for the first twenty miles (revving and shifting madly)
the guy that told me to do this said not to let the engine idle after first startup
get on the road immediatly
he said the engine is already broke in and you want to only break in the rings so get to it

[dlb]

there is a link on the forum somewhere about breaking engines in. i just searched but can't find it. basically the information is the same as what xirdneh just said: drive it really hard and do not let the RPM stay constant. you want lots of hard acceleration and deceleration.

do it safely, obv.

[4wdEconoBox]

Ok, so I placed the order this morning and went ahead and got the complete master rebuild kit that included the oil pump, timing belt kit, etc. I went with .020" oversized pistons and rings. I'm hoping that my crank doesn't have to get turned because I only ordered standard mains and rods. If it has to be turned then I'll cross that bridge when I get there. If the crank is within spec, should I go ahead and get it polished while I'm at the machine shop?

Also does anyone know off top of their head what size and length bolts I need to put it on an engine stand?

Whats the best/easiest way to clean out oil and coolant passages?

Is there anything else I should do while I have the engine out? Other than replace the clutch, which is already in my plans. I also am going to clean up the engine bay, smooth it out some maybe, since I removed all of the a/c stuff, and spray it a dark brown/chocolate color, it'll be a nice contrast to the tan/gold exterior of the car. Is there anything else I can remove or relocate to clear out the bay while I have the chance? Iwant it to look nice and simple! Throw out some ideas if you have em! I also need a good color to paint the engine block, crossmembers and any other accessory that is paintable.

I feel like there was something else I wanted to ask also, but I can't remember at the time....haha

Thank y'all for all of y'alls help so far!!!

[irowiki]

Depending on the cost, you could polish the crank yourself with fine grit sandpaper.

[larry mcgrath]

DO NOT use sand paper to polish the crank journals -the proper material is called Crous cloth -this is Extreamly fine ,use it with light oil. Your machine shop should offer this service. Larry

[4wdEconoBox]

Yeah, I figured that if the machine shop doesn't charge an arm and a leg then I'll get them to do it. If it ends up costing too much, then I'll just do it myself. I just looked up some tutorials on how to do it with emery cloth and a flat shoe lace. Depending on the condition of the crank, I was gonna start with 400 grit and work my way up to 1000 grit. If it isn't in bad condition, I may start with 600 grit. As for the light oil, would WD-40 or penetrating oil work?

And when it comes to assembly lube, would white lithium grease work, or what is the preferred assembly lube?

[Petros]

hand polishing the crank using a strip of fine wet and dry paper, with solvent or light oil, will put a better surface on the crank journals than a machine shop can do. We hand polished the crank journals on the 980 hp turbo Nissan 3.0 L race engine, the car never suffered a bearing failure and was undefeated on the racing circuit. Do not think that just because a big machine does the work that it is better than you can do by hand. Hand surfacing the head like I show in the head gasket thread puts a more flat surface than a machine shop can produce, this we also did on the race engines for Nissan.

I would not use lithium grease, you can buy assembly lube in any auto parts store, a small tube does not cost much. If you can not afford it just use clean motor oil.