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.