VesperWillow

The #4 cam bearing in my block apparently just walked out. Anyhow, the bearings were installed by a reputable engine shop near my house. Car ran fine for the first month/4k, then began to slowly lose oil pressure until finally it dropped into dead-man's zone.

Anyhow, here's a shot of it from one angle: http://www.ls1gto.com/forums/showpos...9&postcount=37

here's a shot of it showing the exposed oil galley (thus the sudden drop): http://www.ls1gto.com/forums/showpos...2&postcount=51

Does anyone have a clue what would cause this? No abnormal vibrations, motor ran like a champ up until this point. Camshaft isn't damaged, nor is anything else. The bearings are shot throughout the motor, the lifters (surprisingly) aren't damaged either.

Any clue what would cause this? I would think bearing installation, but why would the motor run fine for a month solid and then clunk out? Up until I parked it and yanked the motor out, there was no abuse, no revs over 4k (except for when it was tuned, 1 month prior to this), it was pretty much babied.

Need help / suggestions / answers fast. Engine shop is looking at the block, and their answer is pretty much "we have no clue what could've caused it".

VesperWillow

Nothing?

See5

iTrader: (53)

Unfortunately that is not that unusual. It is hard to get LS replacement cam bearings to stay put. Some engine builders replace the stock ones routinely, which invites the problem.

Red99C5

Either the cam bearing was not fitting tight enough on the block, or the cam bearing ID was too small and it was trying to seize on the cam. I have seen motors where you have to hone the cam bearings after install because the cam was too tight. Whenever I have a block machined, I always take the cam so the builder can check it.
Also, check the cam on that bearing journal. If it's tappered, it will also make the bearing push out.

redgto4u

iTrader: (8)

when you put in a new cam do the bearings HAVE to be changed?

Red99C5

No. They last a long time. Usually only time they get replaced is when a cast iron block gets dipped in a hot vat prior to machining. Something you don't do with aluminum blocks.