Michael,

Sounds like you're still moving right along with your engine.

I have a Haynes manual that was written in England, so terminology is sometimes a problem.

It says "Radial play of crankshaft in bearings" is .030mm to .050mm. I believe that this is main bearing clearance tolerance.

It also says "Radial play of big end bearings on crankshaft" is .030mm to .060mm. I believe this is rod bearing clearance.

Since .1mm = .004inches, these "radial plays" are quite tight compared to the Chevy's I've built. .05mm(the max main bearing clearance) would be .002 inch.

I hate to say it, but it appears that this may be where your oil pressure was going. Good news is that you should be able to find a good crankshaft shop that could grind the crank and get everything tight again. Since it sounds like you now have the engine out, maybe this wouldn't be too much more trouble.

These are just some thoughts for you. I'm sure you'll want to consult an official MB manual for clearance spec's before taking such a step.

After rereading your successive posts, maybe by replacing the upper half of the main bearing, you will get your clearance where it needs to be on the mains. Remember, using plastigage will not allow you to check for a flat crank. But maybe you're close enough with new bearings. Keep checking and good luck.

Best of luck,