964 oil leak question

[02jake]

I have an oil leak that looks to be coming from the base of the barrel and running toward the head. I have oil residue where the air deflector is bolted onto the case, thru bolts or cylinder base? Engine has approx. 50k miles. Any incite would be helpful. thanks

[PeteKz]

Has the engine ever been taken apart? If not, then unlikely it's the base gaskets or O-rings. I'm not a 964 expert, but in the earlier air cooled engines, oil in that area almost always comes from leaks further up, especially in the area of the oil breather cover and oil pressure switch or sensor. You will need to do some investigating to find out where it's coming from. No easy remote answers.

[porschedude996]

When I rebuilt the engine in my ’72 911T, many years ago (1986), most of the o-rings were turned to plastic. This was my 1st experience with 911’s and first thought they maybe they were supposed to be plastic. It was a fleeting thought… I think at the time of original assembly, I’m sure Viton wasn’t used by Porsche due to cost at the time. Nitrile was probably a 100th the cost back then.

[john walker's workshop]

964 and 993 are famous for case through bolt o-ring leaks.

[porschedude996]

Originally Posted by john walker's workshop

964 and 993 are famous for case through bolt o-ring leaks.

John, what is the latest and greatest on sealing O-Rings. Are the green Viton currently the best?

[john walker's workshop]

Yup. Can't trust the blue ones.

[porschedude996]

Originally Posted by john walker's workshop

Yup. Can't trust the blue ones.

Thanks John!

The blue ones are what I took out of my never disassembled 1983 3.0.

I first bought blue’s from our host and returned.