M20 rear main seal leak @175k? Sanitary pad?

[Gene in NC]

M20 5s has rear main seal leak @175k while it's fraternal twin M20 at at 142k is dry as a bone. M20 rear main leak common? Any condition pressuring the crankcase that might cause leak?

If simple rear main leak I'll put a sanitary pad on it. This trick transferred from inboard boats with GM engines, all of which have bad rear mains. Looked at boat with Chrysler engines that belonged to Pontiac dealer. Response to jibe about GM dealer with Chrysler engines, "All GM engines have rear main leak, Chryslers don't leak a drop. GM for cars but never in my boat."

[winfred]

bimmer crank seals are generally good for a few hundred thousand miles

[Gene in NC]

Trans is full and oil doesn't stink so it must be rear main. With Shell 15w50 oil consumption is 1/4 qt per thousand so it's not leaking much, just enough to spot the drive.

[Jeff N.]

Simple fix.

1) Drop exhaust
2) Drop tranny
2a) Drop flywheel
3) Install rear main seal
4) Replace Flywheel
4a) Replace tranny.
5) Replace exhaust.

C'mon...what's holding you back?

[Bruno]

M20 5s has rear main seal leak @175k while it's fraternal twin M20 at at 142k is dry as a bone. M20 rear main leak common? Any condition pressuring the crankcase that might cause leak?

If simple rear main leak I'll put a sanitary pad on it. This trick transferred from inboard boats with GM engines, all of which have bad rear mains. Looked at boat with Chrysler engines that belonged to Pontiac dealer. Response to jibe about GM dealer with Chrysler engines, "All GM engines have rear main leak, Chryslers don't leak a drop. GM for cars but never in my boat."

Probably your oil pan gasket leaking... it looks like it is the rear main seal but it isn't... BMW rear main seal don't seem to leak that often, pretty rare.

I would put my money on the oil pan gasket... Good luck

[Gene in NC]

Please forgive incomplete thread opening. PO had pan gasket replaced about six months ago. What's holding me back from seal replacement is $11 fix that takes 20 min. Kept black, black, black, black diesel drips off drive for ten years.