Clutch accumulator
06-23-2005, 07:29 PM
#1
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Thread Starter
Clutch accumulator
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.
06-24-2005, 12:26 AM
#2
Rennlist Lifetime Member
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. It looses pressure and dumps the assist. They go bad and create a hard pedal. It is a common issue.
The issue is the valve in the slave. It looses pressure and dumps the assist. They go bad and create a hard pedal. It is a common issue.
06-24-2005, 02:01 AM
#3
Pro
Thread Starter
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.
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.
06-24-2005, 08:45 AM
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I have exactly the same problem at the moment. It only happens 50% of the time when left over night or for a few days. I took it to my dealer but he said it was ok but my warranty is going to run out in october.
After reading this thread i think im going to take it back to another dealer and have them fix it, but i too wasnt that bothered as it only happens when left.
Stephen could you please confirm what the faulty part is likely to be and if left will it fail completely?
Thanks.
After reading this thread i think im going to take it back to another dealer and have them fix it, but i too wasnt that bothered as it only happens when left.
Stephen could you please confirm what the faulty part is likely to be and if left will it fail completely?
Thanks.
06-24-2005, 08:46 AM
#5
Rennlist Lifetime Member
It will get to the point that the pedal is choppy. You will feel it resist but more like a sticky door. The rule is if it goes down in less than a 24 hour period you need to check the system. There is a test outlined in the books on how to check the slave.
06-24-2005, 11:04 AM
#6
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Thread Starter
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.
06-24-2005, 04:03 PM
#7
Rennlist Lifetime Member
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).
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).
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10-04-2005, 07:17 PM
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I have exactly the same problem on my X50. It goes in this Thursday for a new 'clutch servo'? This is what the dealer told me the problem was, but when i pick it up thursday/friday i will let you know what was repalced/faulty.
10-07-2005, 03:49 PM
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Just got my car back. The tech says it was a faulty 'sphere' which is part of the slave cylinder. The clutch is engageing lower down now and it feels better. Tech says he checked the car this morning after the works and the pedal now moves freely when off.
If youve got this problem and have a warrenty then let them sort it.
PS. They didnt drop the engine.
If youve got this problem and have a warrenty then let them sort it.
PS. They didnt drop the engine.
07-31-2009, 02:14 PM
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I have the same problem of a stiff clutch first thing in the morning but was wondering before I replace the accumulator, could it just need to be bled? I noticed the excellent DIY post included bleeding before and after the replacement.
On one hand I would hate to go to the effort to do that then repeat the work to replace the accumulator. On the other hand I wouldn't want t buy the part (~$120) if the system only needs to be bled.
On one hand I would hate to go to the effort to do that then repeat the work to replace the accumulator. On the other hand I wouldn't want t buy the part (~$120) if the system only needs to be bled.
