Removed Alternator
 

Removed the alternator only to find that it was replaced with a rebuilt back in 95 which was poorly rebuilt. But in any case is there anything I should do while I have it, fan and housing out. I plan on cleaning up the fan and housing. Just curious if I should be checking anything while I have the top of the engine exposed.

Also I found an air difusser attached to the back of the alternator. It has two air difussers that direct air to the drivers side of the engine. I cannot find any info anywhere for what this is or its purpose. Why would it channel air to only one side?

What you are calling a diffuser has been called a hub elongation, hub extension or air guide by Porsche. The blower or fan doesn't produce a purely axial flow of air but one that also has a clockwise whirl when one looks into the fan from the rear. The two vanes on the air guide are actually there to ensure that the left or driver's side cylinder fins get adequate cooling air. Be sure and reinstall the air guide or you may end up overheating cylinders 1 & 2. While you have the alternator out, clean off the top of the engine and cylinders; remove any debris such as leaves, rag remanents, pine needles, mouse nests, etc. When you reinstall the alternator ensure you reconnect the ground strap to the top of the engine. It attaches to one of the bolts at the top case seam. Cheers, Jim

Thanks alot that does make sense, why doesn't any of the manuals show this?