Crankshaft Oil Seal

There is a front seal and a rear seal. They are usually lip seals. They wear with age. Front seals are often replaced together with the timing belt because the area is already accessible. A blocked crankcase ventilation system can raise pressure and push oil past seals, so checking it prevents repeat leaks.

The seal lip runs on the crankshaft surface.

Leaks can contaminate belts. Replacement often needs special tools.