What could be the cause of oil leaking out from behind the starter and isn't the head cover gasket in a 6 cylinder 1995 Grand AM?

Answer 1

When you say "behind the starter", do you mean between the starter and the transmission "dust cover"? If that's where the oil is comming from, it's probably a "rear main seal" that is leaking. With the engine running, remove the oil fill cap. If you see a cloud of oil vapor exiting and can feel air comming out from a few inches away you probably have "blow-by". That's a condition caused by high pressure gasses leaking past the piston rings when the engine is running. When that occurs it usually destroys the rear main seals and there just isn't much that can be done short of a replacment engine. Rear main seals can also go bad for other reasons. Also: This is a 3.1 litre V-6 and it is derived from the old 2.8L engine. The 2.8L had a distributor and it was installed at the rear of the engine- the area where the transmission is attached. The 3.1L engine shares the same basic engine "block" as the 2.8L and the hole where the distributor used to be located is now used by an oil pump drive adapter that is driven by the camshaft which then in turn drives the engine oil pump via a 6" long HEX-sided shaft. This "adapter" is sealed with a thin brown "o-ring" and they seem to be only available at the GM dealer. At least I only buy them there. The O-ring is not expensive but the replacement is too involved for someone without tools, knowledge and patience. I say this because the most aggravating thing about replacing this o-ring is that the heater pipe connector usually snaps off at the slightest touch and then you have to spend time drilling or otherwise extracting the remanants of the connector and installing a new one. I always plan on this happening, you should too. Oil leaks from this adapter and it's o-ring and then runs down the block between the engine and the transmission bellhousing and appears to be caused by a leaking rear main seal but isn't. Also, intake gasket end seal leaks can leak oil in the same way with the same diagnosis- rear main seal-NOT. Start repairing oil leaks from the top of the engine down. Gravity complicates things sometimes. Things are not always as they appear.