[slow-poke]

I realize, there are a lot of variables: oil type, engine load etc, but if an engine is run under normal driving conditions how much do the bearings/journals wear say after 100,000 miles?

For example if the rod bearing clearance started out at 0.002
would you expect 0.0025 or 0.005 after 100,000 miles?

Any wild A** guesses?

 

[mavman]

There are too many variables. Some don't even make it to 100,000 miles. Others are still breaking in at 100,000 and you couldn't find a sign of wear anywhere inside. Even then, the overall design of the engine can be a factor.

It'd be hard to say, at least IMO

 

[67Coug]

With a constant film of oil between the crank and bearings therre is no metal-to metal contact so there is no wear and bearings can last indefinitely......IF: if the oil is kept clean, if the oil is never contaminated with anti-freeze or raw gasoline, if the engine is never allowed to ping (detonation pounds out bearings; ever tear down an engine and have the rod inserts just fall out of the rod or the mains jsut fall out of the caps? This is a sign of detonation. The crush fit has been lost and the sides of the bearing have actually pulled in) Sitting a long time without running doesn't seem to hurt. A few years ago my dad was needing an engine for his '40 Ford. He found two, in a bus and a pickup, that we know had not run since the mid '60's and had been sitting outside, although still in the vehicles. There was still a coating of oil on every bearing!

 

[1 Bad 88 GT]

The only real wear on the bearings is at startup. I've seen bearings with over 150K miles that barely have the babbit worn off the bearings and others with less than 10k that are nearly worn through.