Transmission Rattling

[stanmo]

Hello,

Two months ago, my transmission made a rattling noise. The dealer found out that the throw out bearing guide was broken so they replaced it (along with the throw out bearing). At the same time, they found the RMS problem and replaced the engine and flywheel. However, the transmission is still making a rattling noise but it is not as loud as before. It is loud enough to be annoying especially with the AC and radio off. The noise is NOT present when the car is cool. The noise would get louder as you drive the car for a longer period of time. I went to two different dealerships and they told me that this is normal. Does anyone know what is going on here? Any tips? Thanks in advance!

[Loren]

If the dealer did the work before on the throwout bearing then that should not be the cause. I assume the rattle is somewhat different in sound.

The dealer should be able to tell if the rattle is a broken weld in one of the mufflers. This has happened a few times on very new cars so it is not to uncommon.

[stanmo]

umm... the funny thing is that when I step on the clutch pedal, the rattling sound goes away... any clues? thx..

[Tool Pants]

Maybe they forgot to put oil in the transmission. :o

Try another car and see if it is "normal."

When you have the clutch pedal down the gears inside the transmission stop spinning. Porsche uses a dual-mass flywheel, and this reduces transmission noise from the gears. If the flywheel goes bad then you hear transmission noise. Guys that switch to a conventional single mass "racing" light flywheel hear transmission noise. They should have inspected your flywheel. Just a guess over the internet.

[stanmo]

Hey Tool Pants,

Thanks very much for your insight. Do you think that my clutch is defected? I know they replaced the flywheel when they replaced the engine for me (stated on invoice). Do you think that the noise might go away if I change it to a Sachs Level 1 clutch? I am thinking that my clutch might be defected. BTW, I have just changed the transmission oil last week and the rattling noise is slightly softer. Thanks.

[Tool Pants]

So much for that internet noise guess.

Suggest you go to the 2 dealers that said it was normal and ask to test drive a few cars just like yours and see if you hear the same noise. If not, then take a mechanic on a drive(s) and point out the difference.

[stanmo]

Thanks. I will check out my friend's car tonight.

[Scouser]

There's a TSB regarding Dual Mass Flywheel check procedure that concerns complaints of noise/rattling/nocking in the transmission.

Go to Loren's TSB section using the link at the top of the page. The TSB can be seen there.

[stanmo]

Thanks for the info. Do you think the problem resides within the flywheel since it is new? Also, I've heard that a clutch will make noise if the springs on the clutch is defected. Is that true?

[Scouser]

Not sure. The TSB is a long shot. It's probably doubtful that your flywheel is faulty as it is newly replaced. But, I have known of faulty parts or even badly fitted ones.......;-)

Springs on the clutch tend to be sqeeky when you operate the clutch pedal. They don't sound like the rattling noise you describe.

[stanmo]

Thanks Scouser. I have scheduled an appointment with a Porsche rep.

[santalk]

Hi,

Wondering if you ever found out what was causing this problem? I seem to be experiencing the same type of problem on my 1999 C2 6 speed. Car has 75k miles and has a rattling sound at the lower (2200-3000) rpm range when the car is warm. Other than that it shifts and drives smoothly. All signs from what I have read are pointing to the clutch or related components. I hope it is not the transmission or engine, but will get it in to check out soon.

[santalk]

Anybody?