Just completed installing new seals in the SS sleeved front brake calipers on my 67, bled all 4 calipers, and now hear a "hissing" sound when the brake pedal is initially depressed. Brakes seem to work OK, but did not experience the hissing sound prior to installation of the new seals. Has anyone experienced this and what is the cure for it? As always, thanks in advance for your help. Rex NCRS #8089
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Re: Power brake hissing
is the hissing soud loudest near the power brake booster(assuming its a PB vette)? mike -
Re: Power brake hissing
Actually, it sounds as if it's coming from under the dash, and I only hear it momentarily when the brake pedal is first depressed, sort of sounds like "air brakes" on a big truck.Comment
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Re: Power brake hissing
Nothing under the dash using vacuum , unless you have AC. Check to see that the vacuum white plastic valve that goes in to the booster is OK and sealed.Comment
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the filter has been damaged
there is a air filter element that goes around the push rod of the power brake housing that lets air in and out of the power brake shell.you my have damaged this filter when bleeding the brakes if you use foot power to do the bleeding. i have seen these filters get moisture in them,freeze up when the car was left outside in cold weather and cause the car to have no power assist till the ice melted because the air could not move in or out of the power brake housingComment
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Re: Power brake hissing
Some noise might be normal as air always flows into the back of the booster when you step on the pedal.
Clems suggestion sounds like a good place to start.
DukeComment
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Re: the filter has been damaged
All,
Thanks for your responses, however, brake bleeding was accomplished using a "Mighty-Vac" vaccuum pump brake bleeder, no "pedal pumping / power bleeding" techniques were employed. The car has always been stored inside in a climate-controlled environment, booster hasn't been off car for several years now. Any other suggestions before I pull the master cyl and boster off? Thanks, RexComment
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if the power assist is working
the sound you hear is the air on the drivers side of the booster diaphgram going in and out. the filter is there to cut down on the noise and keep dirt out of the boosterComment
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