996/997TT Clutch Accumulator
Knocked out a couple of cars today. Had a Boxster come in for bank 2 oxygen sensors, which were replaced quickly, and it was back on the road. Then it was off to save another stripped wheel lug thread on a buddy who was switching track tires for a trip to MAM.
Then I had a 996TT come back in from last week so we could do some more work. The clutch hydraulic accumulator had failed which causes a really heavy pedal when the engine is not running. It also causes a pedal when driving that feels somewhat catchy in spots. It is a pretty common failure on the 996/997TT’s. We also changed the oil while it was in.
After a bit of work under the car, the accumulator comes out.
My “special tool” P9218302.3b It’s a tight fit to get the accumulator out. This accumulator had been replaced in the past as the wrench size is different from the original to the replacements.
I have probably replaced dozens and dozens of accumulators in the past, but I have never really figured out why they fail. Tonight I decided to cut one open to find out. 35 minutes later, I had it in two pieces. The bugger is very thick metal to hold the pressure.
What I found inside was a rubber diagphram in the bottom. There were not any holes in the membrane, so I am not really sure how it fails.
After a lot of work, I got the diaphragm to pull out. It was under a significant amount of pressure, and there was quite a bit of pressurized fluid underneath the diaphragm.
Is this how it is suppose to look? I’m not sure. I will check the next new accumulator I replace. By sticking a rivet or something down the hole in the top, I should be able to instantly tell if the diaphragm is close to the top nipple, or at the bottom like above.
UPDATE: 7/16: Another accumulator replacement, and I was able to confirm that the picture below is how the rubber diaphragm should be when new. It should not be collapsed.
9 CommentsLeave a comment
March 17, 2011 at 4:05 PM
Does a porsche 997 that is not twin turbo, have an accumilator????
March 17, 2011 at 4:42 PM
No, the 997 non turbo did not use a hydraulic accumulator. Hope this helps!
June 26, 2013 at 12:40 PM
Dealer tells me accumulator is “weak” on my 2001, 73k mi, TT coupe. I have not really noticed heavy pedal. I’m inclined to wait another few thousand miles and take it in for major service at the same time. Is there danger in this approach? Is it likely to fail catastrophically? If so, what is result? More mechanical damage? Strand me?
June 26, 2013 at 1:45 PM
Sometimes the hard pedal is thought to be normal as sometimes it can happen gradually and people don’t notice. The clutch pedal should be super easy to push in and out with virtually no effort. Anything more than that, and it is starting to fail. A quick test is with the car off push the clutch pedal in and out a few times and see how hard it is. Then start the car. If it gets easier, then the accumulator is likely on it’s way out. Eventually the pedal will become very stiff with both car on and off. It will not strand you by any means, just get hard to operate the pedal. Another symptom of a failing accumulator is the pedal feels notchy as you operate the pedal in and out.
June 26, 2013 at 2:43 PM
Just went out and really paid attention. Have come to the conclusion that I didn’t notice because, at this point, I actually prefer the heavier feel.
What I have noticed for some time is that with pedal ‘on the floor’ to crank engine, it will actually fall when it fires.
December 3, 2013 at 11:18 AM
was needing some input on a 2001 996TT,
while driving the clutch pedal went to the floor with little resistance while shifting and did not return to its normal position. I had no problems prior, do you think the slave cylinder has failed?
December 3, 2013 at 5:45 PM
Yes, sounds like either the slave or the master has failed.
December 17, 2013 at 8:05 PM
We were working on a 2001 tt and the slave was leaking. So we decided to replace both the slave and accumulator. After we got it done and all back together about 50 miles later the high pressure line to the slave started to leak. Couldn’t see were the leak was but had to pull inlet pipe, air filter housing, alternator, ac compressor and power steering reservoir and found that the main hose had rubbed against the motor and caused a hole. Hard to find but it was about right behind the ac compressor. Looks like someone had been in there before cause they had covered the return line with some rubber hose and zip ties. So I ordered all the hoses today and was curious have you ever changed these hoses and if so how long does it take. I do see pretty much everything on the left side of the motor does need to come off to replace the hoses. Thanks Joey
December 18, 2013 at 11:37 AM
I haven’t had to replace those lines fortunately, as it sounds like a bear!