stiff brake pedal?

Post by **lhd** » 31 Aug 2007, 11:42

Iv'e been having a problem lately with the brakes.
When I start off the pedal is stiff and will not move as if the servo/m cylinder has gone.
This seems to cure itself after about a mile of slow driving, It first happened whilst in Amsterdam so I thought I would repair it when I got back to the UK.
Survice to say I never had the problem again until setting off to Crornwall the other week.
It now seems, the more I use the brakes ie (down hills in cornwall) the more it happens, when using the van in normal driving conditions this does not occur.
What I would like to know is this...

As its a diesel could it be the vacuum pump or pipes, and is there a way to test the pump?
I dont want to buy a new master cylinder unless I really need one.
1.6d n/a
Rob.......

Post by **toomanytoys** » 31 Aug 2007, 13:35

SOunds like the vac side of the servo is leaking... or blocked..
a hard pedal would indicate no assistance, so you need to inspect the pipework and pump (the D/TD's have a pump dont they?)

Could be worth running it for 10 mins and switching off and listening very closely to the servo on the master cyl.. if you can hear a whistling its that at fault.. otherwise it could be in the pipework..
someone with more specific D knowledge should be along in a min...

Post by **lhd** » 01 Sep 2007, 10:32

Had a look this morning and I'm getting vacuum at the servo end of the vacuum pipe so I guess its the servo that needs replacing.

Does any one know if they are universal ie early or late.
There's one on ebay at the moment but the grommet for the vacuum pipe is on the wrong side so maybe they are sided.
Rob..............

Post by **toomanytoys** » 01 Sep 2007, 11:23

Can you apply vacuum to the servo to see if its leaking..

Post by **lhd** » 01 Sep 2007, 12:01

I cant hear it leaking. plus when I pulled the pipe from the vacuum pump a definite rush of air could be heard.
I did what it said in the bentley manual, as in press the pedal a few time with engine not running, then turning her over and apparently the pedal should sink slightly with medium pressure, this is not happening.
Rob.

Post by **jamesc76** » 01 Sep 2007, 12:02

that to me says its the servo it self oops!

Post by **toomanytoys** » 01 Sep 2007, 12:12

OK.. Bentley.... didnt really need our help at all then...

.. thats good.. IIRC the servo unit is quite expensive.. so you dont want to be changing it and finding it was summat else...

Post by **billy739** » 01 Sep 2007, 17:02

there is a one way valve in the top of the pump to help stop air going back to the servo once drawn out,check this.you can undo the 3 bolts on top of the pump and remove the top.
also try this, run engine give a little rev for a few seconds to with draw the air from the servo, lightly press the pedal down,switch of engine, keep same pressure on pedal, if there is a leak the pedal will lift as the air witdraws, i used to use this method when mot testing, then check for leaks.
has the brake fluid dropped or have you needed to replace the master cylinder lately?
there may be fluid in the servo causing the seals to rot/split

Post by **lhd** » 01 Sep 2007, 17:48

Thanks for the help billy739 I did as you said and the valve is definitely ok.
when doing the pedal thing it did not rise.
also when I checked the pump valve there was a loud rush of air when I removed the pipe from the pump, which has me to believe that the pipe work is all ok and not leaking as it kept its vacuum.
the master cylinder has not been changed ad although the fluid is not at the max its not at the minimum mark either.
By the way I wondered where that valve was, so thanks for that.

Rob....