Thread: My brake pedal makes a "hiss" when I push it...is this normal?

Originally Posted by Young Angus

Sitting in traffic in my disco I notice that when I push my brake pedal I hear a hiss as I push harder. Is this noise normal or is there pressure getting out somewhere where it shouldn't be? Apologies if this is a silly question...

Probably the brake booster is dying, it sucks continually from behind the brake pedal, if it gets worse, soon you might have no power assistance at all.

I'm getting a similar problem with my 101.
I've tracked it down to air being sucked into the brake power booster.
It wasn't doing this until I reco'd the master cylinder.
I'll be watching this thread with interest.

regards
Mick

Mine did that about a year ago. It was a dead brake booster and the end i had such a hard brake pedal, it was getting dangerous.

It was still origanal so i got my value out of it after 12years.

Put a new one on and right as rain.

A major point if you are doing it yourself there is a spacer on your brake booster you might miss.REMOVE it and put it on the new one as this sets the pressure the brake master, if you dont ttake it off you can drive down the road and your brakes will start to lock on it can get messy.

And PS Mick your sound like the brake booster as well, but with yours you can get it rebuilt as for the disco it is not rebuildable.

Good luck
carla

mine has hissed on the car for years...I'm sure I asked about this before and told it was fine as I think I asked about the pedal sinking too after pumping it up

However I will now look into replacing it if that is not the case.

Hmm it might be normal...hey do the discos have abs as standard or would mine not have it?

mine has ABS so the hissing is not just to the non abs

Originally Posted by Young Angus

Hmm it might be normal...hey do the discos have abs as standard or would mine not have it?

Disco ABS was optional, basic system has a brake booster with master cylinder, ABS is on the LH mudguard on the TDi I have here.

Originally Posted by roverspec

And PS Mick your sound like the brake booster as well, but with yours you can get it rebuilt

Good luck
carla

I think mine might be simpler as it was so sudden.

Timeline: No problems > master cylinder leaks > I remove master cylinder > master cylinder rebuilt > I reinstall Master cylinder with lots of prodding, poking and head scratching > hissing noise.

I've done something. I need to investigate further but at the moment, I'm time poor.