[Shiny]

Originally Posted by NeighborsComplaint

Yep, just as I described. The bearing gets hot, sticks to the crank and turns enough to restrict the oil hole. The bearing shell rides up the connecting rod journal. The locating tabs act like wedges to pinch the bearing against the rod, taking up the oil clearance and the whining noise ensues (like a a worn pinion bearing). You have to run it for quite a while while before it grinds enough clearance for the knocking to start.

Best of luck on your rebuild.

Originally Posted by Dragncar

Sounds like you started to stack a bearing on a cast rod. Shut her down just in time to save it.
I bought a 455 that had a severely stacked bearing on a cast rod, crank was just 30 seconds from snapping a rod.
Something you need to inform your machinist about. You need to bore it at least .008 under, not .004 under like you do with a Chevy.
The problem is Pontiacs distort .004 or more a 1/2" under the head bolts. You want your bores completely "round" after all.
If he can bore AND hone with a tq plate, great.
I asked for that on my 461 but he could not do it with his equipment. So he bored it .010 under and honed the rest with a tq plate.
Oh, I would run a Molnar rod all day long over a Eagle and they are about the same money.
I had to have a set of Eagles honed on the big end as they were tight when new.
Good luck with your new build. Getting it back by September would be fantastic.
A stacked rod bearing is why I tell all who want to listen, by forged rods. On just about any engine unless dead stock.
These things are too expensive to do otherwise.

This engine failure has to be very upsetting.

Help me understand the cause better. I don't understand how a rod bearing that's been happy for 15 years decides to check out. How does this happen?

Heat is mentioned, but why?

When one of these bearings is set up with the right clearance, oil pressure is good, and there isn't any detonation, what causes the bearing to suddenly decide it needs to spin?

Does the wear that occurs during start and stop cause the "initial" friction to increase over time or ????

Or is the cast rod to blame? Does it somehow get deformed over time? If so, why?

I know it doesn't matter. The failure happened, the bearing bound up somehow, but I'm curious about what leads up to this.

Mike

[Jay S]

If the bearings were just look at around a year ago while repairing an issue with the dipstick, and they looked good. Given the time frame and miles this all happened, it really should not have happened. If it hadn’t been for that inspection, I would agree it was just time, and for sure it has enough miles on it now it doesn’t owe really you anything. After an inspection, for the short amount of time and miles since then, it sure would be nice to find a smoking gun. Maybe it traces back to the fuel pump going out on the EFI, or something not quite put back together correctly after the inspection. Those are the best things it could be. The worst are something that gets overlooked and put back to kill the next overhaul.