VTC_WS6

iTrader: (9)

This actually happened about a month ago and I never posted but, very disappointing. Picked it up about 4 years ago, 0 mile GM crate motor from a vendor. Put a set of TFS 821's and a Tick cam in it, made great power and ran like a champ for 4 years, then this:









Bearing actually managed to roll over the upper half of the opposite shell, never saw that before. Car never ran low on oil but it did have a propensity to lift the nose pretty good when you'd stab it (no bumper stands or anything like that). Really bewildering considering the low mileage of the motor but, there it is. Curious if anyone has seen anything similar to a stock bottom end?

G Atsma

Define "pretty good". You could have starved it for oil during one of those times. Only needs to happen once.

KCS

iTrader: (20)

That's what a spun bearing actually looks like. Once it happens, it's really difficult to determine the cause because there isn't much left of the bearing.

pantera_efi

iTrader: (1)

Hi VTC, my guess is the same as yours, the nose lift.

One common observation is the location of the "spun" bearing.

When the Oil Volume is LOW, the forward bearings suffer greater than the rear bearings.

This is due to HOT Oil.

When the Oil Volume is diluted by Air, the rear bearings suffer greater than the forward bearings.

The Air will take the easy path and "blow" the Oil Wedge away from the journal.

Just a "guess" for your case.

Lance

A.R. Shale Targa

iTrader: (2)

Number seven cylinder was lean and/or hot
Once the detonation smoked the rod shell to the copper, it heats the rod big end and then spins/overlaps the shells
My detonation theory holds true if upon tear down you find other rods where the cap shell looks new and the rod shell is showing copper in the middle

showdog75

iTrader: (8)

Nice nails...

VTC_WS6

iTrader: (9)

I've already torn into it, no detonation, piston tops are clear of any evidence of knock, no expansion of the piston skirts, no evidence of beating on any other bearings.

VTC_WS6

iTrader: (9)

5 posts in, longer that I thought it'd take

G Atsma

Well, it's a Monday, sooo, you know.....

AnotherWs6

iTrader: (17)

I was gonna comment as well. Guess I just did.

dogsballs

Low oil, nuff said

BigEd_72455

iTrader: (7)

Jerk it all apart, get the crank turned, Have the block vatted, new cam and rod and main bearings, reuse the rings, put it all back together and go back to beating on it. And get a Melling High Volume pump for it.

Old Geezer

iTrader: (3)

The wart complements the nails....