I'm gonna re-resurect this one, with some photos I thought I'd share.
Last weekend I helped a mate from GTOUK pull his engine after he developed severe rod-knock. This is what we found
Here's his sump from outside;
....and from the inside;
The oil pick-up strainer has been slightly bent on the lip by the sump damage;
But it still leaves the question, how much dagae can a sump take before it damages the oil pick-up strainer? The only way to see how much clearance there is, get the trusty angle grinder out......
This is a cut away section of an un-dented (but knackered) sump on an old block/pump (if you look closely at the first picture, you'll see where one of my rods made a bid for freedom!);
So, a few millimeters of damage is enough to block the flow of oil substantially. There is only half an inch at best between the pick-up screen and the bottom of the sump pan.
Steve