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Minor Engine Rebuild - Maybe - Options...


Everyone says I'm a jerk.
NAXJA Member
Torrance, CA
Okay everybody, here's the deal. I've got a bad head gasket (there will be posts about this stuff seperatly, first things first though) and I'm thinking as long as I'm tearing it down this far I might as well go a little deeper.

Now the engine runs strong (well, it did right up to when the head gasket died), no knocks and such, but I was thinking that I'd just go for rings, main bearings, rod bearings, cam bearings, and maybe lifters. I am at 200k right now, and I have to pull the head off and the pan off (change the rear main while I'm at it). What do you all think of how possible this is?

Can I do this in-vehicle?

Who's went my route and what did you find for wear? My biggest concern is that I don't want to have to bore the cylanders, just a little honing to give it that pretty cross hatch design.

List whatever you think would be appropriate. I'm changing my flex plate as well because my starter makes a horrible noise due to some bad dental work (chipped teeth).

You can do a rebuild such as you describe (probably not the cam bearings, though) in-vehicle. However, you're really talking a fair chunk of a rebuild. IMHO it would be a waste of money to do that much work without going the rest of the way and having the block hot tanked and the bores checked. At 200k more than likely they aren't round and new rings will have problams seating.

If you don't want to pull the block, just get a quicky valce job and head gasket, and maybe drop the pan and do rod bearings and rear main seal.
I am in a very similar situation. I want to do a minor rebuild, mainly re-ring because I think I had a few disintigrate or something (got bad blowby one day, never had any before). So I'm debating on how much or how little to do, though I know I don't wanna pull the block...

any advice? I'll admit, I don't know a whole lot about engines, I could talk for hours about 4 links and schtuff, but I only know the basics about motors...

whaddya think?
Do a pressure test/Leakdown test on each cylinder first before you do anything.
As for pulling the block, it is just alot easier to work on it when it's outside the fenders and you can rotate it around on an engine stand
Sequoia, I just pulled my head, with Rabbit's help, and after 110,000 miles, every cylinder still has the cross hatch honing marks, and no ridge at the top. My machinist is giving me doubts that the head gasket was the problem. He magnafluxing my head right now and I should have it back by the weekend.

We'll see.

I totally agree with RichP about pulling the whole thing if you're going to tear it all the way down. Your neck will thank you for not having to lay under there with your head up.

Eagle is right on here. At 200K on the clock, it's GUARANTEED that the cylinder bores will be out of round, and tapered.

If you hone those walls, it will probably increase whatever oil consumption you have, and shorten the remaining life of the engine before a REAL overhaul is needed.

I go with a simple head refresh, fix the rear main leak, and maybe a set of bearings in the bottom end while the rear main is out.
A "head refresh" at most machine shops consists of this:

1. disassemble cyl. head and clean all components
2. check head for cracks and flatness (grinding to restore flatness is extra)
3. grind all valves and lap to seats (new seats or valves, as needed, are extra cost)
4. knurl valve guides (new guides as needed are extra cost)
5. install new valve stem seals
6. shim valve springs as necessary for pressure (springs that cannot be shimmed and must be replaced are extra cost)
7. reassemble head, and paint exterior

I have not had a head refreshed in about 10 years, but back when I had the last one done, it was about $10-20 per cylinder, so an in line six was between $60 and $120. I would suspect the price nowadays is probably double that.
There is a problem with doing just a head refresh and that is with the new head work comes more compression witch will cuase blow by with old rings. I'd pull it and overhual the whole thing it would be the better choise for time and money.
You are correct, in that a head refresh on a less than totally healthy engine may lead to premature cylinder failure. This is especially true when the miles on the engine are up there.

I would not be hesitant to do a refresh on an engine with 80K miles, provided it's basically in good shape. That same engine at 150K miles would NOT react as favorably to the head refresh process.
The "not react as favorably" part simply refers to increased oil consumption. If you are not burning much oil now, I can't imagine the increase would be anything heartbreaking. Heck, if I were a little thin in the pocketbook, I would do the "head refresh" for now leave the bottom end alone and see what happens. Especially since you have already expended funds to remove the head. You will be maximizing the benefit for the money or time spent in removing the head for the gasket replacement. Later you can snatch the motor and do a rebuild on the block when it proves necessary. Look at the cylinders- do you see a pronounced ridge near the top at the limit of piston travel? You could do some checking with a mic. for wear but you couldn't really check taper with the piston in.