That's a good point about the transmission. Fw, clutch, and pp were all changed. The rattle does go away or lessen when the clutch is in. You can hear this in the clip I think.

 

I take it the gear oil was changed too? Maybe it needs some breakin miles but hopefully nothing wrong with the synchros. No balky shifts rt? Shifts like before. Buzzing can be an early sign of synchro wear. Hopefully it's something else simple. Mike

 

It has been over 5k miles since the change. Car drives and shifts like a dream. No complaints there. Plus, only 60k on the odo.

 

So gear oil change 5k miles ago or all the internals done 5k miles ago? Maybe change the gear oil and see if old oil has any metal shaving residue in it to rule that out? Mike

 

I see what you did there. Nicely played.

 

The fw, clutch, and pp were changed 5K miles ago. I do not believe the gear oil was changed that that time. Really, metal shavings in a transmission can could cause a noise like this? I hope it's something that simple.

 

 

Here's a soundcloud link to a few recordings. No zip files

https://soundcloud.com/user34598673467454

I've been told the tinny sound at the top end is not normal. That is the "buzz" I'm referring to. Keep in mind that in these clips I am basically flat out trying to reproduce the noise.

 

No that's not what I meant. Metal shavings can indicate something wearing inside the transmission ie synchros etc and that affected part maybe the cause of the buzzing. Mike

 

Sorry, but I do not hear the noise you mention.

But if the noise is in fact present and appeared after the work you listed in your 1st post there's probably something -- a line, heat shield, exhaust system component -- something touching something it is not supposed to touch.

IIRC not too long ago -- within the last 3 or 4 weeks? -- there was another post on a strange noise that the owner finally traced to something making contact with another part of the car. The noise appeared after he had some work done on the car, too.

I have not had loose heat shields with my cars but the Boxster had a buzzing converter. The noise was very noticeable at low speed low RPM operation like driving around in a parking lot in 1st gear at barely a walking pace. Upon accelerating in 1st gear the buzzing remained obvious until at some higher engine RPMs and faster speeds the buzzing became lost in the general noise of the car.

Thus I do not think what you are hearing is a bad converter. This doesn't rule out some kind of mechanical failure inside the exhaust system though.

My advice is to carefully review/inspect the work done looking for some line, wiring, exhaust system, even heat shield, not routed or reinstalled correctly.

 

Another question is noise reproduceable on every gear at 5500 rpm? Mike

 

Yes, I can verify the noise for 1st, 2nd, 3rd. Cannot verify 4th as that requires a little more road and/or a track...

In the clips posted earlier it can be hard to distinguish between the Tubi's and the metallic sound. It's most present in the second clip in between the shifts from 1st to 2nd gear.
It wasn't until I started searching around for other folks' sound clips, that I noticed something was different about mine.
One other thing to add is that it only occurs on WOT. If you apply the throttle slowly with less load on the engine, it doesn't occur.

Btw, I searched this forum and others for months regarding this issue. There have been several threads in the past describing something similar, but none were resolved. I appreciate the feedback so far.

 

Listening to the clips again, it occurs most noticeably in "Audio sample 2" at 2.5 seconds and 5.5 seconds. The rough metallic sound in between shifts might be a clue, unless that's normal too?
FWIW, any non-Porsche person who takes a ride notices it right away and will ask about it; so it's not just me. Also, I've driven other 996s with different setups that do not make the noise.

All in all, so long as it's not killing my car I can probably live with it. But if it's a simple fix I'll go in and get it done.


See post #9. I haven't looked for any loose lines or wire, particularly around the transmission.

 

Do u have a hx of hard launching 1/2/3 gears- good in some ways : ) bad in some too : (. Mike

 

Nope, I rarely launch.