Clutch Master Cylinder Squeak

[PA Boxster]

Hi All -

I've been lurking around the forum for while but this is my first time posting. I am looking for some advice on an issue I've been having with my clutch. Specifically my clutch master cylinder makes a squeaky sound when the pedal is depressed/released. I verified that the sound is indeed coming from the master cylinder - it is not the mechanical creak that can sometimes emanate from the helper spring or clutch pivot points. The clutch itself only has around 14k on it (car has 32k, clutch was replaced early when IMS was done) and there is no change in clutch function. The pedal feel is mostly smooth and normal with no change in the engagement point. The only time I think I can feel slight resistance is when feathering the clutch, but this is very minor. The problem seems to have started after a brake flush at a local, reputable Porsche shop. The shop only flushed the brakes - not the clutch - and used ATE 200 fluid. I've read that 9X7 gen vehicles can get master cylinder squeaks when non low viscosity fluid is used, but the LV fluid doesn't seemed to be specced for the 986. Obviously the squeak and flush timing could be completely coincidental. Has anyone else seen this before or have any advice on what to do? Any help is greatly appreciated. Thanks!

Here is a video of the issue: https://www.youtube.com/shorts/BxRF9DygKUA

[Gilles]

You could flush the master cylinder fairly easy with a 'power bleeder' (I have the Motive Power Bleeder and I am very happy with it), just ask the shop the barnd of fluid they used so you buy the same type

The clutch and brake systems share the same recptacle, and according to the shop manual, you leave the pedal at the floor and flush it for 20 seconds (..!), afterwards you manually pull the pedal up and should be ready to use..
Good luck!

[PA Boxster]

Thanks, yeah I figured that would probably be my next step in trying to fix the issue. Is a squeaky master cylinder a common problem with old clutch (brake) fluid?

[Gilles]

Originally Posted by PA Boxster

Thanks, yeah I figured that would probably be my next step in trying to fix the issue. Is a squeaky master cylinder a common problem with old clutch (brake) fluid?

Honestly, I am not sure, but since you mention that the noises started after the repair shop flushed the brakes and Not the clutch, it could be an indication, at least after you flush the slave you will know that all the hydraulic system has fresh fluid..

[PA Boxster]

Thanks yeah, i guess that's the best way to proceed. Would it be a bad idea to flush with LV fluid (ATE SL.6)? I'm pretty sure it is compatible with ATE 200. I guess the only thing is I'd have ATE 200 in most of the brake system, then the SL.6 in the clutch lines. The mixing would dilute the LV feature but maybe resolve my issue?

[JFP in PA]

Originally Posted by PA Boxster

Thanks yeah, i guess that's the best way to proceed. Would it be a bad idea to flush with LV fluid (ATE SL.6)? I'm pretty sure it is compatible with ATE 200. I guess the only thing is I'd have ATE 200 in most of the brake system, then the SL.6 in the clutch lines. The mixing would dilute the LV feature but maybe resolve my issue?

First of all, to my knowledge, LV brake fluids are not recommended for pre 2005 Porsche vehicles.

I would suggest getting some fresh ATE 200 and access to a Motive bleeder and flush both your brakes an clutch systems until whatever fluid is in there is gone from the common fluid system they share. The Motive system is particularly good for these types of flushes as it pushes new fluid to force out the old.