95 4x4 3.0 - brake problem

[rvschulz]

brought the truck to a 'speedy' oil change and they check all the fluids too ... well shortly after brake performance starts deteriorating to the point of undrivability. after some looking ... i determine they did not replace the cap on the brake reservoir properly - it was sitting there loose ...

i reseated it - it's a little tricky ... and now i am getting braking again. however, i am noticing a hissing under the dash. do i need to bleed the brakes or has something failed.

note: the brakes "jumped" 3-4 times after i got the cap reseated and then stopped. brake fluid is still high in the reservoir and the brake pedal is very stiff when the engine is shut down - could i have a vacuum leak ?

 

[fourwd1]

Pin point the hiss, maybe it's in a vacuum line.

 

[desertrunner88]

May need to be bled. Or could be a brake booster.

 

[turbosol93]

The hissing sound really sounds like the booster has failed...mine did the same thing last week. Replaced the booster and was good to go for a mile or so...when you replace your booster be sure to check the rod going into the master cylinder ( i didnt)...make sure its adjusted the same length as the original one or you will have problems like i did.

 

[rvschulz]

it's the booster. went to the junk yard and pulled one off with the master cylinder - an Aisen. is that any good ? anyone can hook me up with a video about changing everything out and bleeding the brakes ... would appreciate it.

roger

 

[turbosol93]

well if the brake booster is identical to the one that has failed on your truck all you need to do is swap boosters....no need to change our mastercylinders uness you know that your old one is bad... steps for booster replacement 1 remove the 4 12mm nuts holding the master cylinder on. 2 pull mastercylinder a few inches forward until it clears the studs for the booster. 3 remove the spring and pin that holds the brake pedal up (theres a small pin that holds the brake pedal pin in place) 4 remove the 4 12mm bolts holding the booster to the firewall. If yours is anything like mine you may have a 14mm nut holding a carpet bracket in place... 5 wiggle brake booster out of cavity under hood and then install in reverse order.

 

[ChoochCharlie]

Highly recommend changing all of the fluid too. Brake fluid, when exposed to air, absorbs water right out of the air and loses performance, safety, and contributes to corrosion in the braking system. New brake fluid is light colored, as it absorbs water it turns darker. If the cap was off a while, the color is probably dark and time to change.