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73-87 Chevy _ GMC Trucks => Brakes, Frame, Steering & Suspension => Brakes and Braking Systems => Topic started by: bcstingray on April 17, 2016, 03:42:06 pm

Title: Brake booster hiss
Post by: bcstingray on April 17, 2016, 03:42:06 pm

The power brake booster I have, used but was to be a good one, has a hiss coming from the back side inside the cab. My truck is a 73 that I switched from manual to power brakes using an 81 up booster. I take it its just bad. Anyone else come across this problem?

Title: Re: Brake booster hiss
Post by: bd on April 17, 2016, 04:01:07 pm

A continuous hissing sound from the booster is a perforated diaphragm.  Temporarily remove and cap the vacuum hose that connects to the booster then start the engine.  If the hissing stops, replace the booster.

Title: Re: Brake booster hiss
Post by: bcstingray on April 17, 2016, 04:15:44 pm

I'm pretty sure it's bad. Will the rod that attaches from the brake pedal to the booster rod (81 up booster) fit on a 73-80 booster?

Title: Re: Brake booster hiss
Post by: bcstingray on April 19, 2016, 08:25:45 am

Would it matter to put a JB5 booster on a JB3 system?

Title: Re: Brake booster hiss
Post by: bd on April 19, 2016, 12:07:19 pm

Using a dual-diaphragm vacuum booster (http://forum.73-87chevytrucks.com/smforum/index.php?topic=16967.msg133295#msg133295) is a common upgrade.