mike250

truck: 3vze 4x4
i don't have the original engine but i did a compression test at 160k miles and and got about 170 psi before i did a valve adjustment. 20k miles later i need a new head gasket. i don't think it makes since to do a complete rebuild, i think i might want to replace the rings while the heads are off. (thoughts?) i was thinking is it possible to lower the front differential and take out the oil pan instead of taking out engine block to replace rings, then just use a flex hone with block still in. maybe it wont take longer? thoughts and opinions?

millball

If your oil consumption was minimal, you probably will get plenty more engine life without replacing the rings.

I recently did a headgasket job on my '95 3vz at 140,000.

I thought about re-ringing but my engine ran well before, so I left it alone.

I have re-ringed several 22r type engines with their blocks in frame, but never a 3vz yet.

If the pistons are out, no reason not to replace the connecting rod bearing shells at that time. Those are inexpensive.

I think it would be difficult, if not impossible, to replace 3vz main bearing shells with the block in frame because all the main bearing caps are cast into a single reinforcing girdle.

Let us know what you decide, and how your repair work turns out!!

Jimkola

Granted, the engine compartment looks busy, but it's not a hard engine to pull. There's some stuff you'll need to get out of the way, but shoot, most of that comes off anyway when the heads are removed.
I would do a leak down test on the cylinders before head removal. That's good info to have. Once you pull the heads and can do a visual, combined with what you learned from the leak down test you can form a cohesive game plan

mike250

well this certainly isn't just a scratch





cylinder with crack








Is this something a machinist could weld then grind away without changing bore dimensions? or would it need a sleeve? or is the block trash? the crack doesn't go all the way down the bore. seems to be just the inside of the bore with the crack. the head gasket seating area seems fine. if i left it alone i wonder if this problem is going to grow over time until i burn coolant through the crack or loose compression?

millball

The block might be sleeved, but it'd be easier and cheaper to find another rebuildable block.

Crazy to think of running this one as is.

Jimkola

Curious. What was the leakdown percentage of that cylinder?

mike250

i had the heads taken off before your first post.

Jimkola

Doesn’t matter. Was just curious if that would have shown in the test. Test results give you a direction when nothing is obvious during disassembly. This crack would over ride any test result.
Odd crack, can’t recall ever seeing that. Doesn’t look like overheating caused it. Freeze?

mike250

The #4 cylinder had a exhaust valve with zero clearance. I blame the crossover pipe for that. this crack is in cylinder #4. I'm thinking if Toyota decided to put a different exhaust system in instead of the crossover pipe I wouldn't have the cylinder crack

Jimkola

I doubt the cross over had anything to do with it. Design flaws like that would have meant that huge numbers of 3vze blocks would have cracked just like yours, and I haven't seen that.
Where did that engine come from?
One possibility is the crack has been there for awhile, and hadn't yet caused an issue. It was a problem waiting to happen. Is #1 cylinder where the gasket failed?

mike250

engine came from a friend who is a mechanic. previous engine had a bad knock. quickest fix was to just swap it. it was free. Correct, cylinder 1 had the bad gasket

coopster

That is really something. Obviously didn't go thru to water jacket. Wonder how deep it was.

mike250

Ok so i was totally convinced that the block had a crack because of how jagged it looked and because of how it extended all the way past the ring wear area. But i took it to a machinist and had it magnafluxed and found out it isn't a crack. So i got the engine put all back together and it lives again. Thanks for all your assistance everyone

wallytoo

iTrader: (1)

i’m really curious what it was, then. it sure looks like a crack. fwiw, last year i took the head from my 3-53 detroit to a machine shop to try to find the crack that was allowing coolant to get into the air box. magnafluxing it showed no crack, but when the shop started milling it, the crack became obvious.

mike250

Wow i hope that doesn't end up being the case. The interesting thing is when i took it to the machinist he said it wasn't a crack but a scratch just from looking at it. After he had said it wasn't a crack i had him magnaflux it just to be safe. The Machinist has over 40 years of experience working in his machine shop.

millball

What components did you replace???

mike250

I replaced bearings for crank and rods. First compression ring i took out had a smaller end gap than the new pre gapped ring i got. But the second compression ring that i took out had a much bigger gap than the new one. Strange...(I only looked at one piston set) So i replaced all piston rings. Truck idles lower than it ever could.

ZARTT

Hi:
Don't you think that a scratch would be almost perfectly vertical?
I mean that how could a piston, which rides vertically in a bore, cause a wavering scratch like that.
That is a crack, plain and simple. If it were a scratch there would certainly be more than one.
I am of the opinion that reusing that block, sleeved or not, is a false economy that will come back to haunt you.
I wish you luck.
Art.
P.S. It is usually hole #6 that suffers because of crossover heat.