I originally thought the small oil leak at the rear of the pan was the pan gasket, it was never much but it got on my nerves enough for me to remove and replace the pan gasket with one from 928 Specialist that is made from rubber rather than cork. Guess what? The leak was still there. Right before Sharktoberfest 2007 I decided I would replace the seal, on the journey down to Anaheim the new seal leaked worse than the old one ....
Here is a great writeup on the rear main seal on Rennlist, seems there are others out there with the same problem.
On a 5 speed you need to remove the clutch and the flywheel, on an auto it is more involved as you need to remove the flex plate which in turn means moving the transmission backwards.
Below is a picture of the leaky seal.
Problem here is a drove the seal in too far, it should just be flush. Live and learn.
I spent a lot of time prepping the area, used a small file to take of any sharp edges and scotch pad to clean any residue. Ended up looking like this.
Next task was to smear the surfaces with oil before putting the seal in, then placing the seal in. A neat trick is to use the flywheel to press the seal most of the way in. With the engine in place access is really limited so this worked well, just use 3 bolts to evenly apply force.
You can see from the following picture it just has to go in a bit further after removing the flywheel.
A few careful taps and it was flush, would not take much to make a tool to do this or even a spacer behind the flywheel
Let's hope this one does its job and seals for good, yes I also put some grease in the release bearing too.