miasanmia88

Hi all,

I am a long time porsche owner (1976 911 Backdate) who recently picked up a nice 996.2 CS with relatively low mileage (39k). I haven't had any issues with it since purchasing it in late March. IMS has been retrofitted and car is in great shape and properly maintained.... I have recently noticed a repetive metallic rattle/noise that I can hear with the windows down at idle.... I am not sure if it is only when the car is at idle due to the possibility of the soud being drowned out by driving/engine noise, but it is clear as day at idle. I opened the engine bay and reached to all metal clamps or objects to wiggle them to see if the noise was coming from anything possible loose but nothing....

Here are some intro pics of the car - and a link to a video i took of the sound - much appreciated in advance...

video link: https://drive.google.com/file/d/1NKt...ew?usp=sharing

rockhouse66

I don't have personal experience with this problem, but people on this Forum have often suggested loose parts inside catalytic converters or mufflers cause such a sound.

Joel987

If you give it a slight rev while parked in neutral does the sound go away? If yes it could be chain rattle. Perhaps have someone with an OBD diagnostic tool (PIWIS, Foxwell, Durametric) check cam deviations. If way off your tensioners could be worn. Does it rattle hot or cold? Do you have any excess soot in one of the tail pipes?

DBJoe996

Check for loose heat shields that cover the coils. Take a rubber mallet and tap the mufflers and cats. Loose material inside can create a rattle sound.

Porschetech3

I'm sure it wasn't so bad in person, but that is the worst audio I have ever heard while trying to diagnose a noise. The wind noise and background noise overshadow everything.

Try moving to a quite location, out of the wind, preferable indoors in a quite garage. Then start the recording with the engine off and silence for reference, Then start the engine and try to manipulate/change the tone/frequency of the noise by changing RPM OR doing anything that you know of that will make a different in the noise.

All this info can be used to determine the source of the noise. ( more tricks may also be necessary).