Sporadic ticking from passenger side of '03 C4S, frequency tied to

[Jonathan Mosney]

Hey crew, hoping you can point me (and likely my mechanic) in the right direction with this.

My 2003 C4S with 65,000 miles makes a ticking noise sporadically, coming from the rear passenger side. The frequency of the ticking is tied to my speed, and starts around 6 MPH and up. At that speed it probably ticks about 10x per second. The sound only occurs when the clutch is engaged. It seems to happen more often when I build up some speed (around 10+ MPH), then let off the gas.

Here's a recording of the sound. It's a little hard to hear over the engine, but listen at the following second points: 0:15-0:19, 0:22, 0:25-0:31, 0:37, 1:06, 1:12-1:13.

http://www.mosney.net/porsche/porsche-996-ticking.m4a

Bonus points: there's another sort of whirr/insect-like noise that occurs at seconds 0:35, 1:04. 1:18, 1:25. That seems to happen when I'm decelerating from around 15 MPH, but I'm pretty sure I hear it at higher speeds as well when I'm driving by parked cars or a wall. Maybe not related, I'm just trying to check these things off one at a time.

Thanks for any help!

Jonathan

[BAD124]

This is a challenge. First listen sounds hollow, so thoughts were PSE exhaust flaps, or broken cats. It sounds "tinny" like something on thin metal

Have you tried with PSE open and closed just to eliminate that possibility ? I notice a rattle on mine when the PSE is open, but not when closed which I assume is the valves being loose then under tension.

But you said its only when clutch is engaged which points to drive train...I'll give it another try later on

[fpb111]

CV joint?

[Y2K911]

One of the engine pulleys, perhaps?! Where did you locate your microphone in the cockpit?

Sounds like a tinny muffler to me but there seems to be a fair amount of noise sources, including normal road surface noises it seems. Tough, indeed!

[Jonathan Mosney]

Hey guys thanks for responding. Sorry it's taken me a while to get back - I didn't get an email notification that there were replies. Better check my settings...

@Y2K911 and BAD124 - you may be right about tinny muffler, I know that's a common issue. I had some baffles tack welded back in August due to other rattles and that worked. But the two noises - ticking and whirring - seem to be very related to the speed, especially the rate of the tick, which is definitely tied to the speed. So I tend to think it's something in the drive train.

@fpb111 - I tend not to think CV joint because from my experience they complain mainly when you're turning. This all happens when I'm going straight.

The mic was outside the passenger side, pointed toward the back. I would like to try turning PSE off, but I'm actually not sure if I have that option or if it was even an option for 03 C4Ss.

I decided to take it to the dealer, so I'll write back if they figure it out.