When my 996TT sits overnight (12 hours) it looses some of the clutch assist until the engine is started. I believe it would hold pressure for much longer periods of time in the past. It looses more pressure when the weather is cold. I asked the dealer to replace it under warranty, but the tech said it seemed normal. It doesn't leak any fluid so I assume it's an internal leak in the pressure accumulator. My warranty is about to run out. I can live with a heavy clutch at start-up but I don't want to be stuck with a big expense in the future if it starts leaking fluid. The tech said the motor had to be dropped to replace it. I would appreciate anyone's experience with pressure accumulators and advice on how to deal with the dealer.

 

my tech replaces it without the engine drop. its ontop of the tranny... u should get ur fluid checked and also check for air pockets... basically... u want to blead it. the dealer should at least check if the system has no air pockets and if it has fluid.

 

Thanks. The hydraulic and clutch master cylinder levels are OK. it works fine with the engine running, no mushiness like a clutch that needs bleeding

 

What the heck, an engine drop?? Why? There is no reason for this. I have done several.

The issue is the valve in the slave. They go bad and create a hard pedal.

 

Definitively, from having just been there, the accumulator does not require an engine drop. One dealer wanted $800 to do the fix, another quoted me $450, in the end I got it done under warranty. I also learned along the way that other items can cause a stiff clutch pedal.

 

Will the leaking check valve worsen and affect the clutch pedal pressure in every day driving (with the engine running)? I can live with a hard pedal at startup. I'm not sure how much I should pressure the tech to replace it under warranty.
If the tech won't replace it what's the next step? Try to contact the district manager? I'd like to maintain a good relationship with these guys.

 

Stephen is correct. I recently had this work done on my car under warranty. I really didn't notice the difference until it was replaced. Then I realized how much effort I was using to shift. This should be replaced under warranty.
BTW also replaced a damaged B&M short shifter which broke apart and left me stranded. I replaced it with a Porsche short shifter. The difference was noticeable. The shifts are now a lot smoother and more precise.

 

Stephen,can you outline how the dealer should check it? I couldn't find anything in my shop manual on testing it. I don't have all of the suppliments though. My dealer is low volume and the tech haven't seen many Turbos with mileage. Since the weather here is very hot the pressure assist drop is not as bad as it was last spring.

 

The accumulator is not a warranteed item, but then again it may not be the problem. In my experience with a stiff clutch pedal, a definitive diagnosis was never (can never?) made. It can be several different things. I was lucky to have my dealer do the fix, which involved replacing several items, under warranty. I still don't know, nor do they, what was actually causing the stiff pedal.

 

There are several checks that will make it very clear

Checking clutch booster circuit

Caution. Danger of material damage if the wrong fluid is used for the clutch hydraulic system.
Danger of damage to property if too much Pentosin CHF 11 S is filled or if Pentosin comes into contact with the coolant hoses when topping up or filling in.


Fill Pentosin CHF 11 S only into the supply tanks.
To prevent overfilling and, therefore, overflowing, check the specifications in the clutch, fluid levels description and observe them without fail.
Multiple steering operations (maneuvering) and/or actuating the clutch with the engine switched off change the fluid level in the engine-compartment reservoir. Fluid level rises. In this case, the engine must be run for approximately 20 seconds immediately prior to the fluid level check.
If coolant hoses come into contact with Pentosin, thoroughly clean them with water IMMEDIATELY.
Replace visibly swollen coolant hoses.
1. Checking accumulator

Cold start engine (accumulator temperature approximately 20°C ) and let run for approximately 20 seconds (accumulator is full).
With the engine switched off, depress the clutch pedal repeatedly until an abrupt rise in pedal resistance against your foot can be felt (accumulator is empty). While doing this, count the number of depressions carried out up to the point of the rise in pedal pressure.






If the number of times the pedal was depressed is over 35, the accumulator is -arrow- faulty and must be replaced. 30-8 "Removing and installing the accumulator"
2. Checking valve (pressure-regulating valve)

Note.


Checking the valve in the clutch save cylinder (2.1) is a direct measurement, while the valve in the upper part of expansion tank cannot be directly tested (2.2).
If there is no hydraulic clutch boost after a hold time of 24 hours, at least one of the two valves is definitely damaged.
Prior to the following check, ensure that the system is visually leak tight (externally).
2.1 Checking the valve [pressure-regulating valve) in the clutch save cylinder



Warm engine up to operating temperature (approximately 80°C ). Note. -Take care when handling Pentosin. Wear protective glasses, gloves and protective clothing. -If coolant hoses come into contact with Pentosin, thoroughly clean them with water IMMEDIATELY.






With the engine switched off and the accumulator filled (before switching off the engine, the engine must have been run for approximately 20 seconds without depressing the clutch pedal), remove the plastic return line -arrow- from the expansion tank. To this purpose, push the red thrust ring in an axial direction, without tilting, towards the tank and remove the line.
Collect the fluid which runs out in suitable measuring equipment (suitable container) and determine the volume of fluid collected.
If more than 4 cm3 is collected after a measurement period of one hour, the valve in the clutch save cylinder is faulty and and the save cylinder must be replaced. Removing and installing clutch slave cylinder - 30-4 "Removing and installing clutch slave cylinder". 2.2 Checking the valve (Pressure-regulating valve) in the upper part of the expansion tank This valve can only be checked indirectly. A fault exists if the hydraulic clutch boost function does not last for an entire 24 hours, but where the valve in the clutch save cylinder is functioning correctly (Test 2.1).

 

Thanks! Is it necessary to have the special tool to pop out the low pressure return hose or will a couple of small screwdrivers work?

 

No, screwdriver is fine.

 

Took it to Park Place Porsche and they replaced it. I can now depress the clutch 16 times before it looses assist. Clutch seems lighter overall.

 

I recently had the same problem fixed under warranty at Boardwalk Porsche. The service is much better there than at Park Place. Unfortunalty, I now have another clutch problem -- slipping. The two problems are unrelated, however.

 

I just had my clutch pressure accumulator replaced today at Hennessy Porsche (just north of Atlanta). They do great service.