JerrySab
Well-Known Member
- Joined
- Jul 11, 2020
- Messages
- 217
- Age
- 44
- City
- Los Angeles
- Vehicle Year
- 1988
- Engine
- 2.9 V6
- Transmission
- Automatic
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Guessing the block has already been bored 1mm? Was every hole bored the same? Do you know any other history on the engine?
If it was mine I would write the block off and find another one unless you simply can't. 1mm is 0.040"... in my mind if you're dealing with multiple cracked cylinder walls, there is not enough meat left to tolerate heating & cooling cycles... or the block was plugged up and coolant wasn't getting to those areas. 1mm oversize also appears to be the biggest piston you can get for a 2.9.
Sleeving the block would probably fix your problem but I think it would be smart to sleeve every cylinder if they're all 1mm over... otherwise you may be dealing with this in a different cylinder in the near future. Tough call, and spendy, you would need 6 sleeves, pistons, rings, fair bit of labor... plus whatever else they find while it's apart.
I wouldn't assume they thought it was a risk, heater cores leak often and in LA are you really using the heater much? Easier to delete it I guess... and last time I bought a thermostat, I asked for the stock 195 temp and found a 180 degree stat in the box. Installed it anyway since I was in a pinch but that could have happened to your engine too. Who knows.
Machine shop may have just assumed it was safe to bore 1mm over since pistons are available. I would have. Maybe it is totally safe and there was just shoddy work done, who knows. Usually machinists are pretty good at what they do but mistakes are made and if it's a high volume shop, it's probably worse. I had a 2.3 rebuilt by a shop that supposedly was very reputable and it developed a rod knock within a hundred miles and I believe I've been dealing with a recessed valve issue for quite a while that also would be their fault.
Kind of a crap shoot at this point, maybe you can find a block that doesn't need to be hogged out to the max and start over..... or sleeve yours... cost might be about the same in the long run.