squealing noise by brake pedal

[wolfords]

hey guys,
I have been reading for a while, but its my first post. I have a really annoying squealing noise coming from the brake pedle area in my 99 GC. When i hit the brakes it stops for a second. Anyone know this one? Its starting to drive me nuts. thanks in advance

[klr10]

Originally Posted by wolfords

hey guys,
I have been reading for a while, but its my first post. I have a really annoying squealing noise coming from the brake pedle area in my 99 GC. When i hit the brakes it stops for a second. Anyone know this one? Its starting to drive me nuts. thanks in advance

Hi wolfords,

My 99 GC does the same thing, but it's more of a hissing noise than a sqealing. Did you find out what it is yet? Mine's going for its 60,000 service next week so if you didn't find out I'll let you know what the dealer says.

[Myrtle Beach]

Sounds like the wear indicator on your pads- Time for new brakes!!- This tab rubs the rotor when your pads are worn- this way you can change them before you damage the rotors. The tab normally makes noise when your foot is off the brakes and stops when you apply the brakes. Good Luck!

[klr10]

Thanks for the reply, but I don't think it's that - it actually sounds like air escaping. It can be heard when the vehicle is stopped and the pedal is released as well as when moving very slowly.... Could very well be normal - I just need reassurance that it's not a loose pipe or something. It sounds like excess air being bled from the brake servo...? (just a guess)

[JDPascal]

klr10

Sounds like the atmospheric valve in the brake booster is stuck open.

When the engine is shut off, you should have a couple of boosted brake applications from the stored vacuum in the booster... I think you will find that the pedal is hard - no boost- as soon as the engine stops.

The engine may not be running as well as it should either. the air leak will cause a leaner mixture but the computer on the fuel system may compensate for that.

Check for the extra boosted applications after the engine is shut off and then disconnect and plug the vacuum line to the booster and check for a change or stoping of the "hiss"

If both these come up positive then you prolly need to replace the booster..

JD

[wolfords]

Guys,
Finally broke down and took it to the dealer...It is the brake booster. Hope that helps.
S

[klr10]

Thanks Guys, it only seems to do it occasionally at the moment, so I guess I'll wait until it starts to get worse. Any idea how big a job to change the booster? How much to buy one in the UK?