i THINK my booster is bad, but i want to get some advice. when at idle, and constant pressure on the brake, i hear a hissing sound and my idle fluctuated from 1000rpm-1500rpm.

once i let off the brake it goes back to normal. the pedal does not feel weird AND i brake normally.

 

Check for a vacuum leak. The hissing sound may be air trying to come through the brake booster and either leaking out somewhere or being pulled in from somewhere other than the intake manifold.

Easy way to test is have someone stomp on the brakes with the engine running and put your hand over the hole on the intake manifold, if your engine dies completely then you might be ok, if it keeps running even chugging a little you might have a leak. Also, check the hoses coming in and out of the booster to make sure they're not cracked or loose.

 

check the hose first

 

i did, nothing wrong there. the check valve could be faulty right?

 

just letting u know, i got a brake booster i bought from pepboys less then 6 months ago on a car im parting out. contact me if u are interested.

 

depends on how much you want!

 

30 bucks seems like a very good price. Price is firm.

 

alright for sure, you wanna meet up or what? i dont want to drive to the OC!

 

then no thank you. btw im at the boundary of fullerton and yorba linda.

so good luck.