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Brake booster hissing...

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VelodromeRacer

VelodromeRacer

Jedi Trainee
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I need some help. Just as the great fall weather gets here, I had something come up on my BJ8. As you step on the brake pedal, the car makes a pretty loud hissing sound that seems to be coming from within the brake booster. At the same time, the brakes seem like the booster is not assisting either. While stopped and the foot on the brake pedal, the car idle also begins to run rough.

I had rebuilt the booster about 2 years ago, and as luck would have it, it worked well after the rebuild. Any ideas on what I need to do?
 
Sounds like it has gone out on you. Make sure there are no vacuum leaks.
The question is rather to rebuild it once again or go with an aftermarket replacement. Those smarter than me are sure to have recommendations.
 
Well VelodromeRacer, if you do not have a large white cloud of smoke following you around, or the fluid is not mysteriously disappearing in the brake reservoir. Perhaps, you have a dirty one way valve in the vacuum line to the booster, causing it to stick open. OTOH, you may have a defective air control valve where the pads have packed in.-Fwiw-Keoke-AZ- /bcforum/images/%%GRAEMLIN_URL%%/cowboy.gif
 
No white cloud...and no brake fluid in the booster like the first time 2 years ago...the reason I rebuilt it the first time. Is the one way valve servicable? I am comtemplating removing it again and rebuilding it again. The noise is coming from the booster when the pedal is depressed I did confirm that.
 
Hi Velodrome Racer, Yes the one way valve attached to the booster can be removed and flushed out with thinner. If it is the original one it contains a little flat flapper valve that gets stuck in the muck inside, it must lay flat over its aperture to operate correctly. OTOH, an aftermarket one can be placed in the vacuum line if the existing one needs to be replaced..--Fwiw--Keoke
 
Hey Kepke,

I have searched and maybe I am missing it, but any idea where I might find a one way valve in the aftermarket world that is suitable for this if need be?

Thanks,
 
Hi it does not have to be a unique one way vacuum valve most auto parts stores will have them.===Keoke
 
I saw one at Pep Boys a while back. I think it was on the peg board with all of the other " help " generic parts.
 
Ed_K said:
I saw one at Pep Boys a while back. I think it was on the peg board with all of the other " help " generic parts.
Click to expand...

Yep ED. But seems like they be a bit sneaky to locate. E-bay has them.

VDR search "Brake canister Vacuum Valves. JEG's has them a bit pricey though .J C Whitney should also list them. Earlier Japanese cars in the junk yard should also have them and cheep.--Keoke- /bcforum/images/%%GRAEMLIN_URL%%/grin.gif
 
I bought mine from a Nissan dealer. I believe it was off of a late model 240Z. It had the correct size hose fittings and also had a black rubber ring around it to keep it from rattling against things. I paid around $15 to $20 for it. It works great. It will hold a vacumn for ever (well, at least a year!) with the engine shut off.

Mark
 
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