2008 Citroen Dispatch Brake Problems

[angrydispatchowner]

hi all, i have a 2008 citroen dispatch 2.0 hdi 120. 126k on clock.

there seems to be a brake problem, when driving the van for say 5 miles from cold it will come to a stop unless the accelerator is pinned to the floor.

on doing this the brake pedal has loads of travel, all 4 brakes are locked as this has been tested on a ramp,  to release the brakes i have to open the bonnet and pull the vacuum assist pipe off, this automatically releases the brakes.

the servo linkages have been greased and has loads of free movement.

my question is could the vaccum pump be producing too much vaccum? thus puling the diaphram forward activating the master cylinder? or could the servo spring just be weak and not able to hold its own?

at my wits end with it now, any help advice would be much appreciated! 

cheers malc

[paul.h]

Welcome to the forum.

 

An unusual problem. I can not answer your question on the vacuum pump but a few questions that may help others to diagnose the problem.

 

- In the 5 mile drive from cold, have you used the brakes before they appear to come on on their own ?

- With the vacuum hose to the servo disconnected do the brakes work (but with a lot more effort), not stick on and the pedal release normally - just to see if the problem is the master cylinder, such as internal spring broken so the seals do not push back to release the fluid pressure ?

- With the hose connected does the servo hold vacuum and once the engine is switched off, is this released by pumping the brake pedal ?

- Rather than disconnecting the vacuum hose, have just tried stopping the engine and pumping the brake pedal, which also releases the servo vacuum, to free off the brakes ?

[angrydispatchowner]

hi thanks for the reply!

on the five miles from cold, yes the brakes have been applied, but the other day the brakes were jammed on solid while being left idle from cold, (was defrosting windows)

yes the brakes do work with alot of effort when the vacuum hose is diconnected.

servo holds vacuum - but pedal remains like normal when engine is switched off.

i have also tried just pumping the brake pedal and it has released once doing this, past couple of days though it has taken me to release the pressure manually by removing servo pipe.

cheers malc