relinuca

During the recent annual vehicle inspection sponsored by our local dealer, some oil seepage was noted around the AOS of my '99 996 (55K miles).

The Tech suggested changing the AOS' bellows as a possible cure. Is that likely to solve the problem or should I plan on replacing the entire AOS?

Comments will be appreciated.

relinuca

OZ951

The AOS has bellows and a seal where it plugs into the block, either of those could be replaced to address a weep but if your going to trouble of replacing those I'd just replace the whole AOS since they have a well documented history of failing with embarrassing clouds of smoke after startup following a hard run.

Barn996

Good suggestion OZ951.

ivangene

you can replace the bellows without much trouble if you are really lanky and flexible. What was the quote to replace just bellows -vs- the whole AOS

just keep your eyes on it and plan to replace it when the time is right -

Thundertub

I suggest getting the whole new AOS piece since it is a different updated design than your original. The difference in cost over just replacing the bellows may be nominal. I did that 30,000 miles ago and have zero problems since.

Eharrison

There's a big difference between replacing the bellows and changing the AOS.... If the leak is obvious that it's the bellows, I'd do that for now. Replacing everything maybe good insurance about not worrying about it for a while, but really if its just the bellows the cost difference between the two is enough to let it go for a bit. Are there any other leaks on the right rear engine near the vent? Is the car running a rough idle? If so maybe the AOS is going.

IMHO, bellows only if it's the bellows. It's not like you are paying double to take out the tranny etc. The only duplicate labor is getting it up on the lift and unscrewing the lower clamp of the bellows.

It make it simple, find out where the seepage is from and also get a quote for AOS replacement and bellows replacement. Make your call from that...

redridge

There a lot of places the oil can leak in that area.... He might be taking you for a ride. Replace the whole unit.... The new AOS has updated O rings... It has a better chance of not leaking.

TomF

8-10 hours of labor to replace the AOS vs. 30 minutes to replace the AOL bellows... seems like a no-brainer to me.

If it ain't broke, don't fix it. Many stealers and Indies will promote the replacement of the complete AOS when only the bellows needs to be replaced.

If your Indie is suggesting just replacing the bellows it means two things: one, they are honest, two, they know their way around a 996 to know that the bellows can be changed out by itself. As others have suggested, keep an eye out for a failing AOS and plan on changing it out when you do a clutch job or if it shows real signs of failing.

Just my .02.

Cheers,
Tom

jrgordonsenior

8-10 hours is excessive. 4-5 is more like it....

TomF

Not if you are enjoying a beer during your DIY and you also have a Tip (and in my case it's a C4)!