new member + expert

[chippy]

Hi guys thanks for having me on board,

I have a problem with the expert van master cylinder!!!

In one week I have replaced the master with 2 s/hand scrappies and now a brand new one1, the same problem has not been solved!!!!

The brake pedal creeps down under pressure but only with the engine running

Slight pressure === fast movement
Hard pressure ==== slow movement

Problem its the mot next week can some 1 please advise me of this problem


i'm going nuts and £200 poorer

chippy

[Admin]

Sounds like it might be something to do with the servo which uses the engine to generate a vacuum, thus the problem is only apparent when the engine is running.

[504gld]

If this is a diesel engine then there will be an engine driven vacuum pump normally on the end of the camshaft, battery side. Try disconnecting the pipe from the servo (which the cylinder bolts on to) and see what happens. If its firm all the time, then you may need a new vacuum pump or supply pipes. Pumps I'm afraid are not cheap either :-( One last thought, on cars there is a load compensator valve on the rear, I assume you bled all 4 wheels when you changed the master cylinder? If you van has one too, make sure you have some weight in the rear when you bleed the brakes to make sure the valve is open.