# whining sound when brake pressed at rest - master cylinder?



## phatvw (Aug 29, 2001)

When I depress the brake pedal fimly when the engine is off, I can hear a faint, low-pitched whining kinda of sound. Sort of like those little toy moo cans that you turn upside down to produce the cow's "moo" sound.
Is this a sign that my master cylinder is on the way out? Its only 4 years old, but has seen lots of track abuse. Otherwise, my braking system is great. Just bled the brakes and the pedal gives good feedback.


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## Banditt007 (Oct 23, 2002)

*Re: whining sound when brake pressed at rest - master cylinder? (phatvw)*

super blue by any chance? has been known to cause squeeks in the clutch, so i'm assuming the brake seals would be the same as the clutch (material wise) and it would cause that sound too.

Does it sound like something is slooooooowly leaking past something when you hold the pedal down, or does it make the noise when your foot is in motion and then stop?


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## phatvw (Aug 29, 2001)

*Re: whining sound when brake pressed at rest - master cylinder? (Banditt007)*


_Quote, originally posted by *Banditt007* »_super blue by any chance? has been known to cause squeeks in the clutch, so i'm assuming the brake seals would be the same as the clutch (material wise) and it would cause that sound too.

Does it sound like something is slooooooowly leaking past something when you hold the pedal down, or does it make the noise when your foot is in motion and then stop?

Yep, ATE super blue. Yeah I guess it kinda sounds like a slow leak as I press. Then it stops when I lift my foot or if I don't press any harder.


_Modified by phatvw at 9:56 PM 10-21-2005_


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## Banditt007 (Oct 23, 2002)

*Re: whining sound when brake pressed at rest - master cylinder? (phatvw)*

Well unless you get a better suggestion, i would try switching brake fluids to something non-super blue, if you like the super blue try to find the type 200. same stuff w/o blue dye, and being that it has no blue dye no clutch squeel/seal squeek.
I would play it safe though and just change brake fluid outright. I would reccomend the Valvoline dot 3/4. you can get it around here at pepboys and alot of other places, and i have given it a dam good beating w/o boiling it. (stock size rotors/upgraded pads) It is cheap and comes in a quart bottle (as well as a smaller one) but the quart is only like $7


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