floatingkiwi

Hi folks

05 C2s with 58000km on the clock.

Just recently the clutch pedal has started to get a little "stuck" halfway back up in it's travel and it's getting to the stage where I can almost lift my foot off and if it doesn't stay there it will then momentarily spring back up and kick the bottom of my foot.

My local Porsche agent has done some dodgy brake bleeds in the past and another Porsche workshop says this may be air in the clutch system, also the clutch is (with this issue) engaging nearer the bottom of it's travel than normal.

No clutch smells or judder or anything otherwise.

Any ideas/seen this before?

Matt

Rotmilky

How do the brakes feel? Do they still feel the same as before you noted the clutch issue?

The brakes and clutch are part of the same hydraulic system. If the clutch needs a bleed, the brakes should as well. At least when I changed my hydraulic fluid a few month back, I had to bleed the system a couple of times. When there was air in the lines, the clutch would engage almost at the bottom of travel and the brakes wouldn't do anything until I had pushed them in an inch or two.

I didn't note the clutch kicking back out...but I only did one 5 minute test drive before coming back to the garage and bleeding again.

hBomb

I had this happen last winter. My 06 c4s is a DD, and during the work week I only drive it about 7 miles a day. The clutch pedal would get stickier and stickier until I could give it proper long drive on the weekends, at which point the pedal would go back to normal. My theory is that there was condensation in the lines that wasn't getting boiled off during the shorter drives. Have you taken any long drives recently? Might be a good excuse to get out and put some miles on the car!

San Rensho

I would first bleed the clutch. If that doesn't work, the clutch has a helper spring attached to the clutch pedal. That could be binding and causing the problem.

floatingkiwi

Just did a bleed today, full brakes and clutch. Apparently some air came out of clutch slave. Felt good (or at least better) when leaving shop but getting worse again as I drove home. Brakes like the hand of god. ouffffffff.....

Bad master and/or slave letting air in? How could I tell which?
The clutch assembly itself I am convinced is fine due to what's happening and how it manifests.

kkswow12

air

MJBird993

There's really no reason that air ever got into the system in the first place, other than a bad bleed or a failing component. I would suggest that your slave cylinder is probably due for replacement - it sounds like it's allowing air into the system.

The car has low mileage, but age has an effect on components as well.

MJBird993

Sorry, car has low kilometerage...

gpjli2

How about mechanical problem with clutch pedal linkage itself; Sticking and then popping up?

Rotmilky

I've got an 05 with about 75K miles on it. I replaced my clutch a few months back. I noted that my slave cylinder had gone bad (you can see a photo of it here in this thread https://rennlist.com/forums/997-foru...-i-did-it.html). My clutch was quite stiff to use, but it didn't give me a 'kick' like you're describing. I also didn't seem to be getting air in the line with it like that either.

I'm not certain that all bad slave cylinders will behave the same way. Since something it broken, I suppose any number of issues could manifest themselves in different ways. My bad slave didn't behave the way you describe. So, take that for what it's worth.

Edgy01

There are several issues that may be contributors. You have troubleshot the obvious, easy ones, first....

(1) Bleeding the system.
(2) Inspect the helper spring for binding. It's a bitch to remove and reinstall above the pedal cluster, but worth a check. They rarely fail, however.
(3) You can't inspect the clutch slave cylinder for leakage without removing the tranny, so now you're into it. It could also be (most probably) the pressure plate. While in there check the slave for leakage.

Rotmilky

You can take the slave off without removing the transmission. There are two bolts that hold it on. Remove those and it will slide back and out. It's kinda cramped but can be done. I've done it myself. Putting it back in will also be a challenge if the hydraulic system is still pressurized but I've read of people who have managed to do it. There are some photos in the thread I linked to above showing the two bolts that have to be removed. One of them you can't see from under the car and will have to feel around for.

floatingkiwi

OK folks. Problem solved it was the master cylinder which I replaced myself. Not terribly difficult but quite fiddly. I pulled the old slave out but it was fully dry so just slotted it back in - and THAT is a mission.
The master cylinder part num is Master 997 423 171 01
And the latest revision of the slave is 997 116 237 04

For bleeding, use a power bleeder to do the most of it, then follow up with your mate holding the clutch in to do a few "pressure" bleeds to get the last of the air out. (foot down, open nipple, close nipple, foot up, pump for pressure, repeat ad nauseam.)

Matt

Rotmilky

Glad to hear you've fixed it.

What made you focus on the master? Did you remove parts and inspect them before replacing? Or did it end up just being a guessing game? Just curious for my future reference.

floatingkiwi

There was a small amount of wetness/dampness on the bottom of the master, and everytime it went bad I could hear squelching coming from that area, which quickly went away as it pressurised the air in the system. On taking it apart there was what looked like some old water corrosion on the holding clip on the pressure line (through the firewall), possibly it was sucking air in there? Though I suspect the piston had an internal leak by the dampness underneath.