Twice recently I had to hit brakes a little hard in traffic and I pressed the clutch in too in order to take it out of gear but the clutch pedal just hit the floorboard limp, like there was no pressure to the clutch at all. It only lasted momentarily, probably as soon as I backed off the brakes a little the clutch pressure came back, and it has shifted and felt normal otherwise.

I thought maybe I'm low on brake\clutch fluid so I checked but the level is well above the min line and I had it changed by the Porsche dealer only 11 months ago. Anyone know what else might be causing it?

 

Since those two systems share the same fluid, it sounds like maybe there is some air trapped in the system. If the dealer let air enter during the fluid refresh, it takes quite a bit of bleeding to remove it from the system and has to be done via PIWIS or Durametric using the pump activation screen. The other possibility is that your clutch slave cylinder may be going bad or that's where the air is trapped. If you don't DIY maintenance, I'd recommend a trip back to the dealer for a rebleed as that could be a dangerous situation where you either can't disengage the clutch or where the brake pedal goes to the floor depending on where the air moves to in the system.

 

Clutch slave cylinder comes to mind too. It could be air in the line or possibly the seals going bad. In the 997.1 series there is a bleed screw on the slave cylinder. Often when bleeding brakes ppl forget to bleed the slave cylinder. The 997.2 series does not have a bleed screw as it uses a recirculating system instead.

 

As others have offered could be air in the system, or a failing cylinder.

But unless you have had this done recently have the brake and clutch fluid flushed and bleed properly.

I have actually encountered clutch misbehavior in my Boxster from brake/clutch fluid 2.5 years old.

After the fluid flush and bleed the clutch was just fine again. The brakes were "fine" before and after the flush and bleed.

 

Definitely make sure there is no air in the system. Otherwise, a spongy feel to the clutch pedal, grinding of gears when shifting, long pedal travel, and hydraulic leaks under the car are all signs that one or more components of the system have failed. The first place to start is the clutch slave cylinder, as it is easy and inexpensive to replace. If you're DIY capable, here is a great Tech Article that can be of assistance. Good luck!

-Luccia

 

Thanks for all the replies. Messing with brake fluid is one of the few things I don't like to do myself but it happened a 3rd time yesterday so I guess I'm going to take it to the Porsche dealer and have them check the slave cylinder and flush the fluid again. The fluid has always been changed every 2 years but the slave cylinder is the original and is 10+ years old so I expect I'll just have to get them to replace it.

BTW, there's no grinding of gears, it shifts perfectly smooth all the time between all gears, and there's no apparent leaks anywhere. The clutch feels great normally, this loss of pressure only lasts for a few seconds when braking hard and the brake pedal feels fine, only the clutch pedal is affected.

 

This just seems like air or the slave cylinder, more so the cylinder. Let us know what they find out. Cheers!

-Luccia

 

I'm curious, when this occurs is the clutch pedal allowing you to disengage the clutch regardless of pedal hitting the floor without pressure?

 

Well each time it has happened I was putting the car in N in order to stop real quick behind traffic and I didn't try putting it back into gear again until the pressure came back.

Found an older post with some 997's having a similar problem:
https://rennlist.com/forums/997-foru...-roebling.html

 

Had Porsche of Orlando fully flush the system and refill it but the problem was still there when braking hard so they replaced the slave cylinder and it's all good now.

 

Glad to hear it. And thanks again for bringing the flashlight back! They get away from you sometimes!

 

 

Glad to hear this!

-Luccia