Clutch Master Cylinder And Clutch Slave Cylinder, Function Test

Before replacing master or slave cylinder, the corresponding tests must be performed in the event of the following problems.

Noises when pressing the clutch.

• First check the over-center spring or the clutch pedal switch for noises.
• If there are noises, remove the over-center spring and repeat the test.
• Replace the affected component.

Clutch pedal remains on the floor or does not return to the rest position after recoupling (clutch pedal no longer actuated).

• Check whether the clutch pedal returns completely to the rest position. This frees the bleeder hole in the clutch master cylinder.
• Make sure the footwell trim or floor mats are not blocking the clutch switch.
• Advise the customer not to leave the clutch pedal pressed.
• It can interfere with the self-bleeding function of the clutch system, because the bleeder hole in the clutch slave cylinder can not perform its function.
• The clutch hydraulics is self-bleeding only if the bleeder hole is unobstructed.
• The bleeder hole is integrated inside the clutch slave cylinder. It is visible from the outside.

Check the entire hydraulic system for leaks.

• First check the brake fluid level in the brake fluid reservoir.
• Visually inspect the clutch master and slave cylinders as well as the hose/line assembly with its connecting points for leaks to outside.
• Replace any leaking components.
• Bleed the clutch system. Refer to CLUTCH SYSTEM, BLEEDING .

High pedal force 

• The clutch pressure plate or clutch plate is mechanically faulty. Refer to Diagnosis and Testing .

Pedal force:

• Approximately 140 N over the entire life of the clutch

Clutch does not disengage or does not disengage completely:

• Air in hydraulic system, bleed clutch system, refer to CLUTCH SYSTEM, BLEEDING  or check hydraulic system for external and internal leakage.
• The clutch plate is difficult to move on the splines of the input shaft.
• If the needle bearing inside the drive plate (centering bearing for the input shaft) is faulty, replace it. Refer to the appropriate service information .
• Foreign body in the clutch system.
• The clutch pressure plate or clutch plate is mechanically faulty. Refer to Diagnosis and Testing
• During repair work, the wrong parts have been installed or parts have been forgotten (for example the intermediate plate, the alignment sleeves between the engine and transmission).