I think I have a problem with my brake servo on my RST... as I pump the brake pedal engine stals. What can I do about it?

 

It's a vaccum leak mate - I think you'll find the servo's thieving all the air out of the inlet manifold.

 

Oh surprise surprise another Mk4 with a knackered servo

They tend to leak from the front where the master cylinder bolts in, you can check whether yours is leaking by switching the engine off and seeing if any vacuum has been retained within the servo.

 

how?

 

How else?

Press the pedal and see if you can destroy the vacuum

 

With the engine off? pump the pedal or push it ones?

 

The servo should retain its vacuum pressure when you switch off. So on a good servo, you should have a good few presses of the pedal before you destory the vacuum, once you have destroyed the vacuum the pedal will be rock solid and have no servo assistance.

 

So if the servo is in bad condition, the pedal should become rock solid faster ... after one push or something ... right?

 

No the servo will lose its vacuum as soon as the engine is switched off so it will always be solid.

Try holding your foot on the pedal and switching off and seeing if the pedal lifts your foot up.

 

Here we go...
I've raised CO level on idle (before MOT it was lowered) and now the engine doesn't stall as I pump the pedal... Also I've done the test savechaf told about and as I turn the engin off with my foot on the brake pedal it doesn't move at all.