Brake booster squeal

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Jun 27, 2011 | 11:49 AM

mbfan72

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Joined: Jul 2007

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Brake booster squeal

Autocrossed my 87 this past weekend. Noticed a high pitched squeal - like a vacuum leak through a very small hole - during heavy braking. Doesn't seem to be affecting braking. No fluid leaks. Doesn't do it with normal driving but occasionally does it when car is started and brake is applied to shift into drive (no parts rotating at this point so it rules out pads, etc).

I am guessing that it is a small leak in the diaphragm of the booster????

Should I be able to test the booster by applying vacuum to the vacuum hose outlet? I tried with a small hand pump but wasn't sure that the pump would move enough air per stroke to make a difference.

Thanks.

Jun 27, 2011 | 12:15 PM

oldalaskaman

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Joined: Aug 2010

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I vote, its leaking, cheap insuranse to replace it now instead of when you really need it, replace the check valve also, actually, it could be the check valve, swap in a known good one.

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