Inconsistent clutch pedal pressure 996TT

2004 996TT with ~22k miles on it. I am the second owner. I just had the oil changed and the brakes bled and I feel a difference in clutch pressure. Most of the time its a lot harder to press than I remember. I remember feeling a vibration when I pressed the clutch pedal, almost like an air leak. Then every once in a while it will be very easy to push it down. I can't figure a rhyme or reason to why it's inconsistent. It seems too early for the clutch to be worn. I remember reading that the hydraulic systems may be connected between the brakes and the clutch master cylinder? Appreciate any feedback! Thanks, H.E.

The TT have a Power clutch that runs off the power steering pump. There is a small reservoir under the left side front cowl cover near the battery. It uses Pentosin, a flammable fluid that eats rubber. That said there is also a pressure accumulator attached to the slave cylinder. When the accumulator goes bad the clutch action gets variable. They tend to go bad often. My first one failed at 17K miles. http://www.6speedonline.com/forums/9...or-w-pics.html

In order of difficulty: 1. Clutch Helper Spring 2. Air in Lines 3. Bad Master Cylinder 4. Bad Slave Cylinder Does the clutch engagement point change or is the pedal just softer/harder inconsistently?

Sounds like a pressure accumulator going bad. http://www.warehouse33auto.com/parts...6/21/0/11021/0

I think you may just not be use to it. It took me some time. Check the front reservoir for any leakage. The slave and accumulator may be going bad, but I figured this was taken care of on later cars. I could be wrong though.

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^This I did it last weekend, and made all the difference in the world. I wrote something about it in the TT forum. Also a good link for a wrench if you decide to DIY https://rennlist.com/forums/996-turb...today-179.html

Thanks for the replies. @vandersmith - the clutch point seems pretty consistent. It's just the pressure it takes to push the clutch pedal down is generally pretty heavy compared to what it used to be. Every once in a while it will get very easy for a clutch pedal push as I mentioned. I'll look into the pressure accumulator! Thanks!

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The Turbo clutch is hydraulically assisted and hydraulically connected to the power steering pump/hydraulic system. With the engine running -- well according to the factory manual within 20 seconds of engine start -- the Turbo clutch pedal should be relatively easy to depress. If the engine is off the clutch pedal should still remain relatively easy to depress as there is an accumulator which stores pressure to provide boost when the engine is off. This is so when you get in the car and of course have to press the clutch pedal down to allow the engine to start the pedal pressure is as light as it is with the engine running. As others have mentioned what can happen is the accumulator can go bad. While this shouldn't affect clutch pedal effort with the engine running -- more on this below -- one might feel some pulsing through the pedal. This is from the power steering pump. However, once the engine is off the pedal effort goes up. In my experience almost immediately after engine shut off the pedal effort required is high. There appears to be either a working accumulator or a non-working accumulator with nothing in between. If the clutch pedal effort is high with the engine running this is a symptom that as a Turbo owner I'm unfamiliar with. With other Porsche cars, those with an non-assisted clutch, high clutch pedal effort is a sign of a worn clutch. The disc gets thinner and the linkage re-positions and some mechanical leverage is lost hence the higher effort. A failed accumulator can occur at any time. With my 2003 it happened way before 50K miles. (I bought the car with just 10K miles on it.) The techs told me it is not unknown for an owner to bring in a car with a non-working accumulator and when told this to express disbelief as that is the way the pedal always felt: Harder to depress when the engine was off; much easier when the engine was running. If just the accumulator is bad you can continue to drive the car. This is what I was told and what I did. For a while. But you have to check the fluid level in the small reservoir just ahead of the driver under the front trunk lid and under a plastic panel. I think you'll need a Torx bit (security style) to remove the screw that holds this panel in place. Why you should be interested in the fluid level -- or any signs of fluid leaking -- is often -- as others have mentioned -- the clutch slave cylinder can leak and this lets fluid flow past the clutch slave cylinder seal and fluid migrates from the power steering pump tank to the small reservoir and that's not good. If the clutch slave cylinder is showing signs of leaking -- in the case of my car there were fluid stains on top of the plastic panel -- you should not continue to drive the car but get it in and get this taken care of. You can flush away the leaking fluid with hot water. Pentosin is water soluble, fully miscible with water. Pentosin is not quite as nasty as brake fluid, kind of like a copperhead snake is not quite as bad as a cotton mouth snake, or is it the other way 'round?, but it is nasty enough.

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Exactly what I had. You will be pleasantly surprised when you replace the accumulator. It is a good thing to check the slave reservoir to make sure you have no additional issues, like others suggested.

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On the website it says will call or pick-up only, if interested message me as I can ship this. -Jason

This is really great info, thank you. This is a picture of the reservoir you described - it looks like the day it came off the factory as far as I can tell...

Looks fine. Now change the accumulater to fix your problem.

My 996T 2001 (LHD) had that inconsistent pedal pressure. Indeed the reservoir(filled with Pentosin) was at low level. I found that when the clutch pedal was depressed, there was leakage from the connection of clutch master cylinder and clutch pipeline. These is a rubber o-ring in between Clutch master cylinder and Clutch pipeline. What could be wrong? Just the o-ring? Thank you.

rather than start a new thread. What are the tell tell signs of a clutch needing to be replaced in a 2002 996 c4. It has gone from quite heavy (3 years) to much lighter. And at lights it is much harder to do smooth starts. it judders a bit. but doing a second gear start will still stall it. so i am unsure if the clutch needs replacement or the system just needs to be adjusted/bleed.

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I am not familiar with that connection but certainly the o-ring can be bad. If the leak is confined right at the connection I'd risk a new o-ring before anything else, unless someone comes up with a better idea. I don't think that's a quick disconnnect coupling -- these are at the power steering pump -- but if it is be aware there is a "trick" to working the quick disconnect and some do not know of this and end up damaging the quick disconnect hydraulic fittings. Afterwards they leak.

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Not sure the purpose behind a 2nd gear start. My advice is to stop that. You should always start out in 1st gear. A clutch "test" for slippage involves with everything up to temperature take the car out somplace where you can do a full throttle acceleration starting in 4th or 5th gear at around 2.5K RPMs and then you just floor the gas pedal. I mean you don't ease it down but take it right to the carpet and hold it there as long as you can, as long as it safe. If as the engine accelerates you notice an increase in RPMs without a corresponding increase in car speed that's clutch slippage. Let off the throttle the test is over with. No need to repeat the test the clutch won't get better. Time then to get the car in for a new clutch. Unless it was recently done before you do anything else do a thorough brake/clutch fluid flush/bleed. With my Boxster I have found letting this go in one case 2.5 years (vs. having it done every 2 years that the factory calls for) accounted for a very hard to work smoothly clutch and lousy shifting. Afterwards the clutch was once again very smooth and shifting was smooth and crunchy free. If the clutch behavior doesn't noticeably improve after the fluid flush/bleed than come back -- you can start a new thread -- and you'll get help. The clutch hardware may still be ok it may be a clutch hydraulic system problem or a clutch linkage problem rather than a bad clutch.