Ford Focus Brake Master Servo

[Captaintess]

Hi Guys

Carrying on from my last post, now completed a diagnostic on the vacuum pump all this seems to working, now testing the servo the pressure builds up to 600mm HG after a minute, (seems a bit slow to me) and when the brake pedal is depressed the pressure drops to about 350-400mm HG then takes a minute again to build up! If the brake pedal is depressed several times the pressure drops to zero.

Is this normal behaviour for a master servo or do you feel this a faulty item. I have changed this with a second hand unit and was a complete nasty job.

Thanks for your assistance in this matter.

Kind regards and drive safe

[DanGersFord]

Moved to focus section

[ajt]

Is your car petrol or diesel?

You may want to include the details from "your last post" in this one, it saves people who may be able to offer advice having to hunt other posts for the information.

I'm going to stick my neck out, based on length of time it takes to build up vacuum (how are you measuring this), and guess your car is diesel and it is a problem with the vacuum pump.

[Captaintess]

hi, the pressure was tested via the vacuum pump as well as the vacuum hose take off, it is a diesel.

the method used was a vacuum tester that connects to the hose and pump.

the recommended pressure is 500mm HG and my pump is chucking out 600mm HG, so by rights this is working.

Kind regards

[ajt]

The bit that worries me is you say it takes about a minute to build the vacuum? This is obviously not right. I would have thought more like a couple of seconds would be normal.