Input on odd noise

[RF5BPilot]

Car: 2003 996 C2 Cab, 30K, essentially stock. Purchased in '06 w/ 9K miles on it. Under CPO.

Noise: At slow speeds when I get on and off the throttle, through an open window, I can hear a "clack" sort of sound. Not a thud. If you had a group of dowels, standing on their ends and drew them together, they might make a similar sound as they grouped together lengthwise.

It happens in all gears, most noticeably at slower speeds. The higher the gear & the slower the speed -- the more noticeable it is (e.g. at 30mph, it is much more noticeable in 3rd or 4th rather than in 2nd). It may happen at higher speeds, but I wouldn't be able to hear it due to wind noise.

The transmission shifts well (no notchiness or vibration at 3,000 rpm). No klunking. No adverse symptoms.

It has happened since I purchased the car--so this is not a new or recent event.

It is almost as if when the engine torques against the transmission, there is a clacking sound. Guessing, it sounds like it is coming from in front of the engine or further forward....rather than from the very rear of the car.

Back on '06, the service writer at the dealership said the sound was 'normal.' (He never came out for a ride--just responded to a description.) But, I've never heard a sound like this from any other car (much less my previous Porsche's) -- and the car will be coming off CPO in April. So, I'm motivated to solve any issues while under CPO.

Any ideas or suggestions? (I'm ok if this is normal....but if it isn't, I'd like to address it.)

[fpb111]

Car: 2003 996 C2 Cab, 30K, essentially stock. Purchased in '06 w/ 9K miles on it. Under CPO.

Noise: At slow speeds when I get on and off the throttle, through an open window, I can hear a "clack" sort of sound. Not a thud. If you had a group of dowels, standing on their ends and drew them together, they might make a similar sound as they grouped together lengthwise.

It happens in all gears, most noticeably at slower speeds. The higher the gear & the slower the speed -- the more noticeable it is (e.g. at 30mph, it is much more noticeable in 3rd or 4th rather than in 2nd). It may happen at higher speeds, but I wouldn't be able to hear it due to wind noise.

The transmission shifts well (no notchiness or vibration at 3,000 rpm). No klunking. No adverse symptoms.

It has happened since I purchased the car--so this is not a new or recent event.

It is almost as if when the engine torques against the transmission, there is a clacking sound. Guessing, it sounds like it is coming from in front of the engine or further forward....rather than from the very rear of the car.

Back on '06, the service writer at the dealership said the sound was 'normal.' (He never came out for a ride--just responded to a description.) But, I've never heard a sound like this from any other car (much less my previous Porsche's) -- and the car will be coming off CPO in April. So, I'm motivated to solve any issues while under CPO.

Any ideas or suggestions? (I'm ok if this is normal....but if it isn't, I'd like to address it.)

It sounds like the noise that the dual mass flywheel makes when you load and unload the drive train. I notice mine the most when I am backing up the driveway and let off at the street to check traffic. When one loads and unloads the drive train there is a muffled metallic clack and you can feel a little "play" in the drive train. There is a procedure for checking it.

Something like: Hold one face of the flywheel stationary while turning the other half 10 degrees (?10?) let it go and it should spring back. If it doesn't the dual mass flywheel needs to be replaced. I think if you were always going forward and never used engine braking the flywheel would always be against the stops. I was surprised at how easy it is to turn the halves of the flywheel.

[RF5BPilot]

Thanks. I just read up on DMF's and can see how it could create the sound I'm hearing. I heard the term before, never thought much about it. Should have read up on them earlier. An interesting way to buffer vibrations & sudden torque changes between the engine & trans.

Thanks.