Oil Leak Seems to be coming from Jasco 6560T Alternator

[hilltop170]

Yeah, really, where is all the fuss coming from? The FAA certified part was the one that failed. Buna-N is Buna-N is Buna-N. Let someone prove the NAPA Buna-N part is not a Cessna Buna-N part. Geez!

[T. C. Downey]

Yeah, really, where is all the fuss coming from? The FAA certified part was the one that failed. Buna-N is Buna-N is Buna-N. Let someone prove the NAPA Buna-N part is not a Cessna Buna-N part. Geez!

Who would know what it was when they dig it out of the smoking hole, once it is in there, it is in there.

[DWood]

For what it is worth

Buna-N can vary by durometer, compression, temperature range, compression set, resistance to chemical, ozone, oil, fuels, etc to meet the required specifications.

http://www.marcorubber.com/orings.htm Here is just one source of commercially available o'rings with several variations of Buna-N

[Karl Towle]

Finding a significant oil leak from my Jasco alternator, I undertook the task of replacing the seal. I found this thread to be very helpful, but wanted to add a picture to document what the parts actually look like, and to clarify a misleading aspect of the exploded parts diagram provided by George. The bushing depicted just left of the gear, should really be located right of the seal (14). I also might note that after trying several tricks using a slide hammer, or various hooks and pry-bars, I had to give up and disassemble the alternator so I could drive my old seal out from the inside of the front housing - it simply would not budge otherwise. With access to a hydraulic press, the job is not difficult. Be sure to open the back of the alternator and remove the brush assembly BEFORE sliding the rotor out. Reinstall the brushes AFTER the front and back housings are reassembled around the rotor. Inspect the slip rings while you have it apart, and shine them up with a Scotch-Brite pad. Also, as has been pointed out, be sure to replace the O-ring (13) which blocks an alternate path of oil leakage - between the bushing and shaft.

[GAHorn]

Another discussion thread links to this discussion and is why I'm posting: Karl's photo is very helpful, but I became confused by what he mean by his comment regarding location of the bushing (sleeve). His comment appears to relate to the IPC illustration I posted earlier... not his photo. IE., the sleeve/bushing resides within the oil seal. The O-ring prevents oil from traversing beneath that bushing.

I hope this comment is helpful and not adding to confusion.