Hard brake pedal.(vacuum pump ?)

[Guest]

Brake pedal is going hard, then when i leave it a bit with the engine running it goes back to normal then if i keep pressing it it goes firm and i lose vacuum. I'd like to know how to eliminate the cause being a faulty vacuum pump. Thanks.

[E_T_V]

Allow the engine to idle a little (so the vacuum has built up) then turn off the engine. Wait for 5 mins or so, then try pressing the brake pedal. If hard then either the one way valve in the servo has failed or the diaphram in the servo has split and is losing vacuum over time (the vacuum pump can only try and keep up so will be overwhelmed if the split is too big).

[Guest]

If it is the servo ,how easy is it to replace ?

[Guest]

Allow the engine to idle a little (so the vacuum has built up) then turn off the engine. Wait for 5 mins or so, then try pressing the brake pedal. If hard then either the one way valve in the servo has failed or the diaphram in the servo has split and is losing vacuum over time (the vacuum pump can only try and keep up so will be overwhelmed if the split is too big).

OK I let the engine idle .
cut the engine.
waited 5 minutes,applied pressure to brake pedal.
Brake pedal was firm.
Started engine applied pressure to brake pedal-firm.
released pressure on pedal then reapplied pressure and brakes seemed normal I reversed and braked a few times and the vehicule was braking as usual.

This is an intermittent problem,that seems to occur after a longer run.
Thanks for the feedback

[Guest]

Does anybody know the part No. of the the brake servo repair kit fo a 94 td monty ?

[Guest]

If I remove the servo will the fault be obvious to see ?

[E_T_V]

There is a one way valve in the servo pipe. I can't remember if it is an in-line one or one at the right angle junction where the pipe goes into the servo. But if this sticks then it can give the same symptoms. If it was a hole in the servo then it would normally be all the time. The diaphram is also hidden inside the servo so unless you completely disassemble it you'd not really be able to tell either.

[Russ]

As ETV says sounds like the mon return valve is sticking, its in the elbow where the vac pipe goes into the servo

[Guest]

Ok so i might as well start with by replacing the valve,i think i'll probably have to heat the pipe a bit to remove it.

[Russ]

IIRC theres a spring in it that just may be sticking or broken. To remove the valve disconnect from the manifold end then gently prise it form the servo then blow down it. You should only be able to blow in one direction

[Guest]

With servos becoming impossible to find a solution must be found I'm tempted to get one of these http://www.ebay.co.uk/itm/Rover-200-...item3cddb47dfb
I have to try something I'm getting desperate !!

[Guest]

Well I finally got to bottom of my brake assistance woes.
I failed the last MOT so i really had to find a solution luckily a monty came up locally and I was able to get a load of spares.
So I swapped the servo .....still no improvement
So I changed the vacuum pump even though I could feel good suction with the old one.The difference in suction with new one was very noticeable !! and now there's no more hard brake pedal and I passed the MOT
So the moral is-even if a vacuum pump seems to be doing its job,there might not be enough pressure. I suppose all of this could have been avoided if I'd had the proper measuring tool