will740turbo
Member
- Joined
- Jun 15, 2006
- Location
- Portland, OR
Similar post is over on Brickboard.
94 b230ft squirter block with 175k miles. Crank, mains, and rod bearings all original and looking good after a basic polish (not oversize, still under 2 thousandths of gap on all of them). I bought it used and good with 145k miles on it.
The machine shop is saying that the bores are a bit egg-shaped at 3 to 5 thousandths of an inch. They are recommending overbore and replacement pistons up to 10 thouandths over. I had about 155-165psi compression from all the cylinders except number 3 (the redheaded stepchild), which was 60 due to a blown HG checked with a leakdown tester. I almost just did the head work and put it back together, but wanted to check the bottom end too.
Volvo Greenbook says the wear limit is over 4 thousandths *and with excessive oil consumption*. There was basically no oil consumption other than a little leakage from a HG leak from cylinder 3 to the oil galleys. This engine had 0 piston slap, even on 19F mornings running 15w-40 diesel oil - but maybe that thick oil masked the slap.
I'm ok with new mains and rod bearings, and was planning on it, but overbore+pistons adds $400 to my rebuild.
I have never rebuilt a multi-cylinder engine before, and want some advice on this type of thing. If I'm really going to regret not boring it - like the piston slap will be extreme and punching a hole in the block, then sure. I guess I can afford it. But I would rather spend $400 on something else, I think.
I know the TB opinion is usually "Add zipties and replace it when it breaks", but I would like this to last a while. I might be moving into an apartment, and would not be able to yank the engine back out easily. Meanwhile, I've got lots of time on my hands.
So what kind of egg shaped wear is enough to justify overboring? What am I risking if I don't?
94 b230ft squirter block with 175k miles. Crank, mains, and rod bearings all original and looking good after a basic polish (not oversize, still under 2 thousandths of gap on all of them). I bought it used and good with 145k miles on it.
The machine shop is saying that the bores are a bit egg-shaped at 3 to 5 thousandths of an inch. They are recommending overbore and replacement pistons up to 10 thouandths over. I had about 155-165psi compression from all the cylinders except number 3 (the redheaded stepchild), which was 60 due to a blown HG checked with a leakdown tester. I almost just did the head work and put it back together, but wanted to check the bottom end too.
Volvo Greenbook says the wear limit is over 4 thousandths *and with excessive oil consumption*. There was basically no oil consumption other than a little leakage from a HG leak from cylinder 3 to the oil galleys. This engine had 0 piston slap, even on 19F mornings running 15w-40 diesel oil - but maybe that thick oil masked the slap.
I'm ok with new mains and rod bearings, and was planning on it, but overbore+pistons adds $400 to my rebuild.
I have never rebuilt a multi-cylinder engine before, and want some advice on this type of thing. If I'm really going to regret not boring it - like the piston slap will be extreme and punching a hole in the block, then sure. I guess I can afford it. But I would rather spend $400 on something else, I think.
I know the TB opinion is usually "Add zipties and replace it when it breaks", but I would like this to last a while. I might be moving into an apartment, and would not be able to yank the engine back out easily. Meanwhile, I've got lots of time on my hands.
So what kind of egg shaped wear is enough to justify overboring? What am I risking if I don't?