99 S80 crank bearing leak
 

My mechanic pointed out an engine oil leak that seems to be from the belt end main crank bearing. The oil is flung by the 'flywheel' on that end of the engine and drips from the frame in front, mostly. He was concerned that there might be excessive pressure in the crankcase that was pushing the oil out. I pulled the dipstick, which I figure goes straight into the crankcase, and put my thumb over it. I detect no pressure. (is this a valid test?) The Oil Trap was replaced 20K ago, so I don't figure that is an issue.
Anybody else had oil leaking from this point? What did you find?

Maybe it's not oil but grease from your CV boot that is ripped.

A valid concern about the seal considering the age and miles. After 20,000 miles the crankcase vent system is not likely to be the problem. If the seal is leaking, it will contaminate your timing belt.
You can and should do this seal every second belt change. It's only $5 and 5 minutes while he's there. The cam seals should also be replaced if they haven't been yet. It's about that time.
Your mechanic is doing his job by looking out for you and your car.
Check your car's history and your mechanic's history with your car. Ask him what his test is for checking crankcase pressure.
Ed

ed7. what is a valid crankcase pressure test? I read where you loosen the oil filler cap and see if it's being 'sucked' down onto the engine. I actually removed it and help a light sheet of plastic over the opening, but did not detect but just a slight vacuum.

Nah, it's not a ripped CV. However, it find out one very important thing. It's was not engine oil that was dripping from the car, it was power steering fluid. I fixed that by just tightening a hose clamp on the reservoir.

Your test is a good one.
A slight vacuum is what you want, barely noticeable. The pressure would be measured with a water manometer. 27.7" of water column pressure equals 1 psi.
Dwyer Instruments - Primer On How Our Products Work
A balloon placed over the dip stick tube should not inflate.
Ed

Thanks Ed. You've aleviated my concerns about the PCV system being a problem.