Function check for clutch master cylinder and slave cylinder — AUDI

Function check for clutch master cylinder and slave cylinder
Before you renew the clutch master cylinder or slave cylinder you must - in the case of the following faults - first carry out the appropriate checks.
Noises when operating the clutch:
First check the over-centre spring / clutch pedal switch for noise.
If you hear a noise, remove over-centre spring and repeat check.
Renew relevant component.
After releasing clutch pedal it still remains depressed / does not return to its initial position.
Check whether the clutch pedal returns all the way to its initial position, thereby uncovering the vent opening in the master cylinder.
The vent opening is integrated in the clutch master cylinder. It is not visible from the outside.
The vent opening must be uncovered, otherwise the permanent self-bleeding function for the hydraulic clutch system will no longer be effective.
Make the customer aware that the driver must NOT rest his/her foot on the clutch pedal for long periods of time. This could impair the self-bleeding function of the clutch system as the vent opening in the master cylinder can no longer function.
The self-bleeding function of the clutch system can be impaired if the footwell trim or floor mats get trapped, if the clutch pedal switch jams or if the driver rests his foot on the clutch pedal for long periods of time.
Check the complete hydraulic system for external or internal leaks.
Check brake fluid level in brake fluid reservoir.
Check clutch master cylinder and slave cylinder as well as the pipe/hose assembly including connections for external leaks (visual inspection).
If you identify any leaks you must renew the leaking component.
Bleed clutch system
Chapter
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High pedal force:
Clutch plate is worn (except for SAC).
Mechanically defective pressure plate/clutch plate
Chapter
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Pedal forces:
Conventional clutch:
- Clutch lining when new: approx. 115 N
- Clutch lining at wear limit: approx. 160 N
SAC clutch:
- approx. 140 N for complete service life of the clutch
Clutch does not disengage or does not disengage fully:
Air in hydraulic system: bleed clutch system
Chapter
and check hydraulic system for external and internal leaks.
Clutch plate does not move smoothly on input shaft splines (due to corrosion or dirt, etc.).
Needle bearing in flywheel (centring bearing for input shaft) defective, renew needle bearing
Engine, mechanics
Rep. gr.
13
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Foreign body in clutch system.
Mechanically defective pressure plate/clutch plate
Chapter
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Wrong components used or components forgotten when carrying out repair work (e.g. intermediate plate).