02 Disco TD5
Jumped in last night drove off went for brakes they worked but pedal was hard to press.
Not familiar with brakes on a diesel.
but it was just like someone had diconected the servo on a petrol car.
I changed the fuel pressue regulator on back of cyl head 3 days ago have i upset somthing.
Help
Mark

OK - if you've not been playing with the brake pads then the likely is a disconnected or damaged brake servo vacuum hose. Otherwise the wrk you've done may be coincidental to another problem such as:
Faulty Vacuum servo unit
faulty brake vacuum pump
primary or secondary hydrolic brake system failure

I hope this helps,

Ian

Hi Ian
I checked the pipes could not see any obvious problems, it seems to be an intermitant fault so i dont suspect damaged pipe work Would you agree.
if its was pump again would it not just 100% fail.
where is the pump?
Mark

Best Check the servo unit first. This is the classic reason for having to use a lot of effort to depress the brake pedal.
With the engine switched off - depress the footbrake several times to empty the vacuum. Keeping the pedal depressed start the engine. As the engine starts there should be a noticiceable give in the brake pedal as the vacuum builds up. Run the engine for a few minutes before turning it off. If the brake pedal is now depressed it should feel normal.

If this doesnt happen then the servo unit is `compromised' - may be the `check valve' on the bottom of the unit or the unit itself or hoses running from it.

If it is working OK and the problem is intermittant as you say then I'm not sure... It may be as simple as a seizing brake caliper piston on one of the wheels...

Hope this helps

thanks for that i did youre little test, its fine with foot on pedal restart you feel servo come in and go down slightly.
I dont suspect caliper i had them all down and copper sliped them a few weeks ago.
it could be the check valve you mention playing up

M6SJG said:

Best Check the servo unit first. This is the classic reason for having to use a lot of effort to depress the brake pedal.
With the engine switched off - depress the footbrake several times to empty the vacuum. Keeping the pedal depressed start the engine. As the engine starts there should be a noticiceable give in the brake pedal as the vacuum builds up. Run the engine for a few minutes before turning it off. If the brake pedal is now depressed it should feel normal.

If this doesnt happen then the servo unit is `compromised' - may be the `check valve' on the bottom of the unit or the unit itself or hoses running from it.

If it is working OK and the problem is intermittant as you say then I'm not sure... It may be as simple as a seizing brake caliper piston on one of the wheels...

Hope this helps

Click to expand...

Ermmm! Thinking back to my O-Level physics... how do you empty a vacuum?