QMB Oil Pump: Silent Killer

[motorhead]

I was working on a 50mm BBK 139qmb. It had seized rings, gudgeon pin seized into piston and parts of the top corner of the piston melted off...

I chocked it up to the fact that it was being run too long at WOT and being run without the top of the fan shroud. But... my buddy has a differing opinion, he thinks the oil pump failed or is failing. The oil sump was full at the time of the engine failure.

I always thought the oil pump lubricated the head and cam and the piston gets crank case oil slung on it. Can a bad oil pump ruin your piston?

[90GTVert]

I'm with you. The pump should be sending oil up to lube the valvetrain, but the cylinder walls and piston are lubed from oil being slung around by the crank. If he's right and the oil pump is doing it, I'd think you should see some sort of scarring and damage up top too.