Oil Starvation

[Qmulus]

Interesting. I have seen three blown 2.5l engines recently that had bearing failure, and ALL also had pressure relief pistons (early style) stuck in their bores in a position where the bypass port was open. The springs were OK. In that position the engine would not have had oil pressure. Did the pistons stick, resulting in low oil pressure, causing the bearings to be starved and the resulting damage, or did the bearing start to disintegrate for a different reason, as Jake describes, leading to the debris from the failing bearings going through the pressure relief bore (the oil is not yet being filtered) jamming the piston? Either way, I see no reason not to put in the updated oil pressure relief piston and spring. One thing that I have learned is that the Germans rarely say why they update a part (perhaps doing so would be the admission of a problem?), so it is a good idea to use the latest parts when possible.

FWIW, these all had LN deep sump kits and one had an Accusump. They also had lightweight flywheels.

I also saw an engine with a failing dual row IMS bearing (and no other apparent issues), which I thought was supposed to be unheard of, so maybe I am just seeing unicorns...