What can be the cause ?

Hi all,
Since yesterday I notice something special on the brakepedal. When I get in the car to drive off I always press the brakepedal (it's an automatic I have) before I start the engine and since day 1 (january 9th 2001) that brakepedal could be pushed in (go down) for about 1/4th of the total length from top to bottom. Now since yesterday it always feels hard (as if I've been pumping the air out of the system by pushing the brakepedal constantly without the engine running) and can be pushed in maybe 1 or 2 centimeters. When I keep the pedal pushed in and I start the engine I can feel that as soon as the vacuumpump start building up vacuum the pedal lowers to the normal position it had before. Does this mean I have a vacuumleak someplace or what can be the reason ? (When I had my 190E before it said in the book that when pumping the pedal to have it hard and not soft as usual the vacuum system worked ok when the pedal started to get in when the engine started up, same as things happen now. Is another explanation then it didn't work correctly up till yesterday or what ? )

Sounds like you may have a small leak or the one way valve is stuck open alowing air to enter the servo when the engine is off.

Check all pipework for chaffs etc. Dont forget, the vacuum pump does other stuff besides the servo so be sure to check all vacuum pipes.

Check the seal between the master cylinder and servo too.

clutchdust said:

Sounds like you may have a small leak or the one way valve is stuck open alowing air to enter the servo when the engine is off.

Check all pipework for chaffs etc. Dont forget, the vacuum pump does other stuff besides the servo so be sure to check all vacuum pipes.

Check the seal between the master cylinder and servo too.

Click to expand...

Thanks clutch,

When I arrived home this afternoon I opened the bonnet to check whether I could hear some air leaking but the engine was too noisu. When I stopped the engine listened again but couldn't hear any air hissing. Will check it further out (as far as I can that is) tomorrow (if time permits) or so. Ciao.

dont worry bout it willo ,mine has always done it ,and i know all the brakes are perfect ,as i do it all myself, the brakes work perfect. . . .

Not intending to hijack this thread but is there any way of increasing the power of a servo?

Only by fitting one of a bigger diameter, as far as I know.

Thanks. My servo just does not seem to provide as much "umph" as I think it should. I have to really stomp on the pedal hard to brake heavily. No air leaks as far as i can find..everything else tip top... hmm....

small hole in the servo diaphragm?

vacuum pipe collapsing?
"sticky" servo cylinder?

Hi and thanks to all so far but when I started the car this morning everything acted as normal again ? The brakepedal went down to the normal position as it did over the last years and also when starting the engine it didn't go any deeper (contrary as to what it did yesterday when it got blocked right on top). Curieus to see what tomorrow will bring.

willo said:

Hi and thanks to all so far but when I started the car this morning everything acted as normal again ? The brakepedal went down to the normal position as it did over the last years and also when starting the engine it didn't go any deeper (contrary as to what it did yesterday when it got blocked right on top). Curieus to see what tomorrow will bring.

Click to expand...

WAS YOUR HAND BRAKE ON WHEN YOU FIRST HAD THE PROBLEM WILLO. . . .as yer auto adjusters might be sticking a bit [and by hard pressing of pedal can ratchet up the spare play] just a ickle thought. . . .

Clever bugger Ming

ming said:

WAS YOUR HAND BRAKE ON WHEN YOU FIRST HAD THE PROBLEM WILLO. . . .as yer auto adjusters might be sticking a bit [and by hard pressing of pedal can ratchet up the spare play] just a ickle thought. . . .

Click to expand...

No ming,

I never pull the handbrake when the car is in the garage, the place for the beast is so narrow that sometimes I have to push it for- or backwards manually. So much easier with NO handbrake on...

Btw, everything still fine this morning, first thing I do now when I get up in the morning is, after having kissed goodmorning to the wife, sneaking into the garage and try the brakepedal to see the play I've got on it.