weird noise when engaging clutch

[pkstyles]

Hi guys,

so here's the low down. I have this noise that comes and goes intermittently. To me it sounds like a pipe vibrating at a high frequency in a c-clamp that isn't fully tight. Basically it's a metallic screeching.

The following must take place for it to happen:

1. car must be warm, really warm. I have to drive for at least 30mins for it to heat up and have the temp needle at least at dead center.

2. it only makes the sound when the clutch is engaging. not when the pedal is pressed all the way in, or the car is in gear. I've held the clutch at the point where the sound is and it will keep screeching. (possibly tranny vibrations as the source of harmonic resonance?)

3. the rpm has to be within 1600-2100rpm for it to make the sound. If I rev the engine up high or lower, no sound.

4. the hotter the car, the louder it will be - to a point. so to me it must be related to thermal expansion....

My shop is stumped because every time I've been in, I can't replicate the sound, usually because the car isn't warm enough - though even when it's warm, you have to hit that RPM sweet spot to get it to screech.

One more thing, I recently had RUF mufflers put on - the sound started some time after that install. I had the Porsche tech's check out the install and they said it looked solid, so it may not be related but it seems a bit too coincidental....

Anyone have a clue what this may be?

My car is a 1999 C2 996

Edited July 8, 2010 by pkstyles

[greerj1]

Sounds like a throw out bearing. Has the clutch been changed lately, or at all? Is the force required to press on the clutch pedal changed?

Good luck with the search.

James Greer

[logray]

Shameless plug to a clutch kit for your car I am selling:

http://www.renntech....-kit-99-01-996/

:rolleyes:

(includes new oem clutch, pressure plate, and throw out bearing)

Edited July 8, 2010 by logray

[pkstyles]

Sounds like a throw out bearing. Has the clutch been changed lately, or at all? Is the force required to press on the clutch pedal changed?

Good luck with the search.

James Greer

the clutch was changed with the a SACHS clutch kit (a new throw-out bearing is in that kit) in janurary. this "noise" didn't crop up till over 3000kms on the new clutch kit..... weeks after my exhaust install.

clutch feels perfect, it just came back from a Porsche certifed MAJOR 96,000kms service including a test drive from the tech. everything is normal, the sound can't be replicated unless the car is very warm.

[pkstyles]

any one solved this?

the sound is still present, i almost have to "try" to make the sound by engaging the clutch in a specific way when the car is really warm.

i can't replicate the sound often enough to stop by the shop to "show and tell". seems like we have a couple people that have had this problem but no one has posted the cause and or solution.

ideas?

[Loren]

Still could have been a bad throw out bearing or one of the early MY1999 release arms. Did they check the release arm?

[pkstyles]

no they didn't check the clutch release arm yet, since the noise has been happening. is that an easy fix?

Edited August 11, 2010 by pkstyles

[Loren]

There was a TSB to replace the early release arms because of problems. They really should have checked.

I think your only action is to pull the transmission and have a look - something is not right.

[pkstyles]

I would assume the release arm had been updated at some point; my car has a reman engine in it (replaced under warranty). The shop that did my clutch is pretty good, they're the LN bearing guys in town here and should be familiar with the short falls of these cars, they should have checked it out for sure. I'll call them and see what they say.

Thanks!

Patrick

There was a TSB to replace the early release arms because of problems. They really should have checked.

I think your only action is to pull the transmission and have a look - something is not right.

[pkstyles]

Fixed!

finally got this taken care of. my post from 6speedonline for those of you chasing this problem:well, i got my car back from the shop, drove over 150kms this weekend and haven't heard even an incling of this sound return. FINALLY!!! after almost a year of this annoyance - the love affair with my car is back!

i don't have a definite answer to what the exact cause of the noise is because I had a whole bunch of stuff done, unrelated to the sound. 2 things that could have been a cause according to my mechanic:

clutch dragging - my master clutch cylinder had to be replaced as the pins was smushed and wasn't fully disengaging the clutch.

idler pulleys - replaced all 3, they were ceased to crap and barely rolled, glazing my serpentine belt.

hope that helps. I'd say get your idler pulleys checked first as that's an easy fix and the most suspect as the root of this weird sound