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Posted

Im fairly new to Citroens and although normally OK on anything mechanical Im totally stumpted with a brake problem.

Can any of you good people out there help me?

 

The brake pedal feels absolutely wooden first thing in the morning or if the car has sat for a few hours.

Braking power is there but it needs all the strength of my right leg to haul the speed down!

A servo issue?

 

The local Citroen dealer has bled the system twice so I (think) I can rule that out. Air in the system would cause sponginess anyway right? So it cant be that.

 

Could it be a vacuum leak somewhere?

 

The engine is also lacking power (in a big way) from time to time but both the brake and engine probs seem to sort themselves out after 5 - 10 mins of driving only to come back again when the car has been stood.

GAAAAAAAAAAARGH!

 

Somebody p l e a s e tell me they have the answer!

Posted

Yes sounds like you have a vac leak or the vaccum pump on end of cylinder head not working , with engine running pull the pipe end out of the brakes servo carefull not to snap it its only plastic , there should be good strong vaccum if you put your thumb over the end .

 

If that seems good put the pipe back into the servo and listen for air leak sound ,again with engine running if you can pull pipe out of servo quickly and put your thumb over hole in servo the vac will be held in the servo till you let your thumb off then you hear the servo suck air in as you let go , if the servo not holding the vac the servo leaking and no good .

 

The engine being under powered is most likely because there is no vaccum to the turbo wastegate control, vac from the servo also does other things like dozer unit control and egr (depending on what year car is ) so can throw up fault codes and so on .

 

Hope this helps

 

Lee

Posted

Lee you're a star!

I had a good look over the system before I did anything; from pump to hose to servo.

Next (as per a tip I found elsewhere) I pumped the brakes with the engine off to expel any vacuum and with foot still on the pedal started the engine.

Hmmm, pedal still rock solid. Not good - should go slowly down if the vacuum starts drawing right?

 

With the engine still running I popped the hose connector off the servo and.... no draw.

Turned engine off (hose still uncoupled) and had another good look around and another head scratch.

 

What happened next I cant explain.

With the hose uncoupled I fired the engine up and....the hose is now drawing air. Weird!

Popped the hose back on and the brakes work perfectly.

 

The next step is to see what happens after the car has been sat all night. Mornings are normally the worst.

 

:UPDATE:

Tried the car this morning and we're back to square one! Damn!!!

 

The car is a 2005 2.0D. The pump, hose servo all look in tip top condition with no obvious signs of damage or wear.

Why should I have intermittent vacuum?

Posted
Could be the hose has failed internally blocking off the air flow when under vacuum from the pump. If you have another car, you could try one from that. If this is not the cause, then may be the pump is worn.
Posted

What Paul says above , a think the pipe has a one way valve in it so that could be at fault , or try taking the pipe off the vac pump end and see if you get a continuous vac there ....if so you know it is the pipe at fault.

 

Maybe worth taking vac pump off cylinder head and make sure dog drive in the end not snapped and sometimes latching on then coming free again, never seen that though .

Posted

What Paul says above , a think the pipe has a one way valve in it so that could be at fault , or try taking the pipe off the vac pump end and see if you get a continuous vac there ....if so you know it is the pipe at fault.

 

Maybe worth taking vac pump off cylinder head and make sure dog drive in the end not snapped and sometimes latching on then coming free again, never seen that though .

Posted

Many thanks for your relies.

PROBLEM IS SOLVED!

 

With the information you gave I did a little investigating (see above) and was able to tell the Citroen garage exactly what was happening.

Unfortunately I couldnt pin point the source of the problem myself but the garage did get to the bottom of it.

 

Lee, you're right on the money with the return valve that screws into the vacuum pump!

 

A ten pounds part and as easy as it gets to replace. Just happy to have consistent brakes back!

 

Cheers guys ;)

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