Strange rattle in back of '01 986S
 

Strange rattling noise in back of 986S when engaging and disengaging clutch. Sounds like sheet metal pieces hitting each other, and the rattle is random. Sometimes is more distinct than others. Have done a lot of searching and listened to many rattles, this is one I have not run across yet.

Can be heard at :07, :10, :20 and :22 in this clip - Box exhaust - YouTube

Heat shields are tight and everything else under car seems to be bolted up. Inside of cats rattle some when I strike with a mallet. Does not follow RPM, sounds like a loose sheet metal part banging around - however it should be noted that I do not hear it at higher revs and speeds. My theory is something loose in exhaust.

Any ideas?

Thanks,

Gary

I have the same issue right now in my 01S. Here is the thread I created.

http://986forum.com/forums/general-discussions/48086-rattle-when-clutch-out-no-rattle-when-clutch-pushed.html

Edit: after re reading what you said, it sounds like our problems may be a bit different.

Just a random thought here on this....Have you checked your axles and CV joints/boots???

Clutch springs ??

Should be a solid clutch unless he changed it out with something else. Our clutches don't use springs as the dual-mass flywheel absorbs a lot of shock and vibration. I would probably guess bits in the cats would be causing the sound.

Thanks everyone for the responses. When I had IMS upgraded the clutch was replaced and bearing etc serviced. Tomorrow I am taking it back to the shop that did the work to put on lift and check out the car. I am also having them replace the motor mount - in the video you can see the exhaust tips move a great deal - motor mount is likely shot and causing a lot of motor movement. Will see how this works. If the exhaust has a rattle inside, will present a perfect excuse to install Top Speed exhaust and secondary cat deletes! I will post after visit to shop tomorrow.

SouthTX: the axles, boots and CV joints look good to me, however I dont know what to look for! Using common sense they look OK, will have shop check this out tomorrow.

PorscheBound - I agree, our problems are different. Based on my extensive searches for noisy clutches etc etc you may want to look into flywheel.

Car will be going into shop soon for clutch, IMS, and RMS so hopefully that will put it all to rest.

Based on my decades of experience as an F1 mechanic, I recommend the installation of the Topspeed system ( regardless of what your mechanic finds). Feel free to share my recommendations with your spouse or anyone else.;)

PorscheBound,

Here is update on my car - in summary I think we may have similar issues. My concern was rattling from back of car on accel/decel. I replaced motor mount assuming the rattle was from engine moving around. This definitely helped but some of the rattle is still there. After replacing the engine mount can still detect some shudder, mechanic says it is the clutch shuddering a little at engagement. I also notice clacking when car is idling with clutch out, does not happen when clutch is in. Previously I thought this was nothing to worry about, but with the clutch shudder and this sound it may point to dual mass flywheel issue. I changed transmission oil, still does it, only when the car is hot.

The clutch/IMS was replaced in March, my mechanic wants to open up tranny to see if something was not torqued appropriately, if there is a flywheel problem, etc. In the meantime mechanic recommends NO autocrossing until this is sorted out. I am dropping it off on Thursday will let you know outcome.

Do you still experience the rattle when idling in neutral?

That clacking noise could be the release arm bouncing around if it's detached from the release bearing. There are ridiculously small clips that are supposed to hold the two pieces together.

Woodsman,

I have the TopSpeed exhaust waiting in garage for install, I may go ahead and get cat bypass depending on how my clutch/flywheel looks later this week.

Woodsman: I hope you are right about the release arm IF it is not an expensive fix!

Ya good luck with that- I would hope the mechanic warranties the work he did for you.

Clutch in the Alternator or AC pulley?