Had some awesome advice on this forum re a previous problem and thought I’d ask again before digging out all the books / visiting the garage etc .
Basically it’s my Ford focus 2002 1.8tddi. Everything was fine brake wise until today when all of a sudden the brake turned from being progressive and strong to completely wooden /stiff and weak as xxxs. I’m not a mechanic but have fixed most things over the years and initially my thoughts are that the servo may be at fault. Fluid levels are fine .
basically what should I look for and in what order to diagnose before writing a blank cheque at the garage ?
your help advice would be much appreciated
many thanks
Bill

Engine off and press the brake pedal several times to exhaust the vacuum in the servo.

Start engine with foot on brake pedal. Does the pedal move down as the engine runs? (It should move down as the vacuum builds up).

Let us know

Hth
Marko

Could be a servo failure or maybe just a vacuum leak. Check for splits/breaks/etc. in any vacuum lines.

Rich.

Do diesels have a vacuum servo? No throttle plate means no inlet vacuum. Either a pump has gone bad or the accessory drive belt has disappeared.

well I’ve tried what Marko said and yes the pedal does depress a little after firing up. After taking for a quick drive the problem still exists and seems worse at lower speeds ( presumably because of the lower vacuum ?)
many thanks to all
What next ?

I’ll get the easy question out of the way:

You’ve not worn the brake pads down to the back plate have you?

quick google find

pads Ok + thanks trekster but not only on warm up

Had the same thing on mine. New servo thingy needed for the price of some decent wheels.

Assuming it pulls up in a straight line and you are just having to stomp like mad on the pedal to get the car to stop then I’d suspect a vacuum issue.

Question will be is the pump faulty or is the servo not holding vacuum?

I seem to remember that these suffer from the camshaft driven push rod (that drives the vacuum pump) wearing and this causes a low output from the vacuum pump. Buy a vacuum gauge and hook it up to the output of the pump – look for at least 500mg Hg at idle.

Hth
Marko