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Air in clutch system

Question : THE clutch on my 1998 Renault Scenic requires several quick pumps on the clutch pedal before I am able to engage or change gears. Even then, the vehicle judders as the clutch re-engages.

Please help diagnose the problem as I do not want to be burdened by another huge bill, just in case my mechanic gets it wrong.

Answer : THE problem that you describe is a typical symptom of air pockets in the hydraulic system. This, in fact, is similar for braking systems.

Air enters the clutch hydraulic lines either because the fluid in the reservoir has been allowed to drop too far, or there is damage to one of the rubber components of the system.

The rubber components include the seals of the master and slave pumps located in the engine compartment and adjacent to the gearbox bell housing, respectively.

Although the fluid level in the reservoir will drop as the clutch wears, it should not drop so much as to allow air to enter the system.

A sudden and drastic drop indicates a leak in the system and a quick check should identify the source of the leak.

The procedure for repairing the master or slave cylinders is almost similar, usually involving the renewal of the rubber components within.

However, if wear is extensive, or if the bores are scratched, renewal is the only course of action. The entire system must be bled or purged of air on completion of any work done.


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