Whirring/whining sound under deceleration and at idle
 

I have an odd whirring/whining sound coming from the rear of the car. If the clutch is 1/2 to fully depressed I get nothing. If the car is under acceleration, nothing. However, at idle with the clutch out and in neutral or when I lift off the throttle while in gear I get a whirring almost siren like sound almost like when you have an AM radio on while going under a metal bridge. I have some opinions that say the throw out bearing is shot others saying it's the pinion bearing(s). Otherwise the car functions as normal. I had the problem for a few days last fall then it vanished. This years it has reared its just this past weekend after a months use without incident.

993 C4 6sp. w/RS lightweight flywheel and clutch.

Thanks in advance for your advice.

Nice stable - have any pics?

Certainly has a bearing like feel to it, wonder if it could be syncros? Fluid level in the tranny? Any evidence of seepage from a RMS or Nose seal? You might ping Noah and ask him to look at the thread...

Thanks Don. I need to change my sig as I sold the GT3 last summer. I found myself driving the 993 far more often and realized it was a $120k "hole" in my garage. The 911 is not picture worthy... yet.

There is no seepage at all from the engine/tranny. I added just a little bit of Swepco to the tranny last fall and it "seemed" to cure the issue but it's back now very intermittently. I have no problem just replacing the TOB as it's a fairly minor expense item and not a huge amount of time. Pinion bearings are a different story though. If indeed it is the pinion bearing I might be better off getting a rebuilt transmission cost wise. By most measure it will run me about $3k to rebuild it or about the same to get a rebuilt one with some sort of warranty. I would be more interested in getting a rebuilt transmission with RS type gearing if possible too. Heres the 993 from an Auto-X last fall.
http://forums.pelicanparts.com/uploa...1240931336.jpg