75ZT Community

One of my students has a 75 CDT and has the most horrible brake problem, which I found out when I tried it today.

An ideas gratefully received please.

Applying the brake pedal, it seems unnaturally stiff and with very little braking effort, almost like a dud servo. In addition, when releasing the brake pedal it only returns to datum position slowly, over a period of roughly 2 seconds.

Any ideas please?

Breather on the cap on the reservoir blocked?

Checked and OK Duncan. Pedal return spring OK as well.

Servo problem?

Would that cause a slow pedal return as well as poor braking effort Paul?

If something is partially seized it could, seals leaking not having maximum effect of the vacuum.

If the seal in the master cylinder that blanks off the reservoir is not sealing correctly then the brake pedal continues downward until either it does seal or the pedal get to the floor and the car does not stop. If the pedal acts as normal then it would seem that the master cylunder is acting as it should.

If the car pulls up, eventually, square then that to me would suggest that the calipers are working correctly otherwise if one was having an off day then it would pull.

The servo is the item that adds the power so either a lack of vacuum or a problem inside. Wiki explains the operation.

http://en.wikipedia.org/wiki/Vacuum_servo

Wiki link now added

Thank you Paul

There's a thread on the OC called slow CDTi servo which has some good info ! Worth checking the vacuum pipe for cracks and leaks , also connected to the EGR (Exhaust Gas Recirculation Valve)

Paul.
it might be worth checking the pipe work also coming from the EGR solenoid, I had to changed mine on the tourer as it had almost rubbed through, and on the FL 1 it had rubbed through.

Thanks Steve