The PCV (positive crankcase ventilation) system removes excess crankcase pressure through the intake manifold. If this system is not working correctly, excess crankcase pressure is relieved in other ways, usually past the oil seals or the oil filler cap, which results in oil leaking out as well.

The volvo "specialist" should have been aware of this however, and I'm certain that a "specialist" checked for any potential PCV problems as part of a $600 rear main seal R&R.

The part is commonly referred to as "rear crank seal". FCPGroton has it listed here: http://www.fcpgroton.com/Volvo700900gaskets.htm#seals

You really want to eliminate other potential leak possibilities before replacing this seal again. Give the "specialist" the benefit of the doubt that he replaced the seal correctly and assume first that the leak is somewhere else (although don't hold your breath). A lot of oil leaks can look like the rear main seal just because of the fact that oil tends to run from all sorts of places down to the bottom of the bellhousing. But again, a "specialist" should have been able to diagnose the leak correctly. So who knows.

Just check your oil level often if you want to put this off. Don't wait until your oil light comes on before you add oil (I'm sure you know this but just checking).



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Matt L. -- Cary, NC -- '89 740 sedan -- '91 740 wagon