Hi all,

Just replaced some corroded brake pipes on my felly, bled the system and I think everything is fine. Pedal is rleatively hard to press when the engine is switched off. However, if I switch on the engine when I depress the brake pedal I hear a noise like air in the system. I guess it comes from the servo unit, is that normal. Actually it does appear to be like that on a couple of other cars I tried this afternoon, but I am just checking.

Don't want the MOT man to fail it if he sits in the car and applies the brake!

Regards,

Yes, a slight hiss as you press the pedal is normal. You shouldn't hear continuous hissing though- that would indicate a vacuum leak. Provided the pedal is firm and doesn't sink to the floor, and the brakes work OK, then you should be OK.

Thanks for your information, in fact the pedal is firm, the hiss seems to be as I depress the pedal. I have checked the servo by depressing the pedal a few times to exhaust the vacuum before finally keeping the pedal held down,. I then start the engine and the pedal goes down a little more as the servo vacuum builds up. After runing the engine for about two minutes I stop it. Then I depress the pedal two or three times, hear the hiss, the predal becomes firm and no more hiss. I think that says the servo is okay.

Having failed the MOT once on brake pipes and CV boots (now all replaced) I don't want to fail again.... simply because I want to get on with many other jobs and who knows maybe even a little relaxion over the bank holiday!! That would be good!

Regards,