Brake booster - leaking diaphragm?

[hotpig175]

Hello out there...

Occasionally on my old Lemans, I get a squealing noise when braking lightly, or sitting at lights with foot on brake pedal. Seems to be coming from brake booster.

My landlord has a Holden Astra, which is pretty much the same mechanically as my car, and he has a constant hissing coming from his booster, which stops briefly when you touch the brake pedal.

I suspect that both of these old wrecks have perforated diaphragms in the boosters, as my (faulty?) logic tells me that vacuum should only be on 1 side of booster. If it's dragging air in around brake pedal actuating rod, surely the booster is munted???

Imagine the solution is to replace booster, as I wouldn't think they can be repaired.

Any thoughts on this? It's VERY irritating!

[MMamdouh]

the booster develops vacuum on both sides of the diaphragm when you are not pressing the pedal... when you do press the pedal the side of the diaphragm facing th pedal leaks all the vacuum and gets to ambiant pressure.

since the other side of the diaphragm (facing the master cylinder) is still at vacuum; it heps the pedal movement by sucking in the rod pushing the pistons in the master cylinder.

if you are having a hissing sound from the booster then chances are you got a leak somewhere and the best alternative is to replace it.

MMamdouh

[hotpig175]

Aha!

That makes more sense. I didn't think I had it right.

Thanks for that - will try another booster.

Cheers.