Brake pedal hard to push down

[wazevan]

Hi all,
Can you help on this.My brake pedal went solid  and I had to put pressure on it to get the brakes to work.I took it to kwick fit(wanted it looked at straight away.) garage and they could not find any probs with it and the brakes worked fine..It happened again yesterday and I noticed ,if I rev the engine the brake pedal goes back to normal.
This has happened  a total of 4 times in 3 months. Any ideas where I should start to look.I have looked at the servo pipes ,but to tell the truth im not sure wot im looking for.
Cheers

[insanitybeard]

It does sound like a loss of servo assistance, could be caused by a vacuum leak, constricted pipe, defective non-return valve in the servo pipe or defective vacuum pump, first place to check though would be the rigid nylon servo pipe from the vac pump to the servo- you're looking for any damage to the pipe, e.g, splits or rubbing through of the tube wall (causing vacuum loss) or signs of collapsing (constricting the flow of vacuum to the servo). This can be easier said than done due to access but worth looking closely at the pipe terminations on the servo and vacuum pump itself to start with.

[Mirez]

Sounds like a loss of vacuum pressure to me. Remove the top engine cover and look for the black ball looking thing (the vac reservoir) - check the pipe from that is intact and not damaged, then follow the other rubber lines around the back and see if any are damaged.

If all is well then as a test, pull off the pipe from the reservoir and have someone start the car - use your thumb to cover the end of the pipe and see if its sucking. If your assistant revs the car with it covered you might be able to hear a whistling noise if any pipes are leaking (you might want to put a glove on, it should suck pretty hard!)

[Mirez]

Dah, you got in there first! Still glad we're thinking along the same lines...

[wazevan]

both,ill try what you say and get back.

[alial]

I had the same problem 2 weeks ago...vacuum loss from the the servo pipe ..disconnect that pipe from the servo and  pressure pump ..99% it is leaking .