Lost Brake Pressure, whooshing sound, no leak?

[socci]

So started my truck and I felt a pop in the brake pedal and then lost pressure in the pedal. The pedal will very easily go to the ground, but it still comes back up freely and the truck will stop when the pedal is all the way down. At first whenever I stepped on the pedal there was a whooshing noise (loud) that sounded like it was under the backseat drivers side. I shut the truck off, was able to build up brake pressure just fine, but once it started again the pedal lost pressure but this time the whooshing sound is gone. My fluid reservoir drained as soon as this happened. It did not fully drain, but the fluid is now very low. I cannot find a leak anywhere though. Any help is appreciated, I need this fixed asap.

 

[koda2000]

the noise sounds like a bad power brake booster, but when they go they usually don't do anything to the pedal height, just the amount of effort required to stop (aka hard-pedal) and don't effect the brake fluid level. still, i'd be thinking about a reman brake booster w/master cylinder. you may find your lost brake fluid inside the booster if the brake master's rear seal is shot.

 

[socci]

Nevermind there is brake fluid everywhere. It's all over the diff, exhaust, pretty much everywhere to the point where I can't find the leak. I'd say from rear seats back is covered in brake fluid. I'm guessing a line gave out? Clearly there is a leak, but if it was a broken line why can I build pressure when the car is off?

 

[bustedknucles]

the master cylinder is designed with two separate areas to hold fluid front to rear in event of line failure you still have some brakes. the rear is on a separate line and is actuated last with pedal push. also when car is not running the engine is not creating a vacuum in the brake booster so you feel every pound of pressure on your brake pedal.

 

[socci]

Makes sense. I'm going to try and get under there tomorrow and narrow down the leak. I'm guessing it has to be one of the rear lines. I am a little thrown off by the sound of air releasing though. I don't see why a busted line would make that kind of noise and it seemed to come from a completely different section of the truck.

 

[bill06447]

The brake line runs in the left side frame rail (where it rusts) then up near the spare tire winch (where it rusts) down to the axle (where it rusts) and across to the rear calipers (once again, rust) time to don the safety glasses and old clothes, refill the reservoir climb under and have a helper pump the pedal...

Bill

 

[jremington59]

If you can help it don't let the fluid drain out and empty the ABS system. Just fill the res and have a friend carefully press the pedal and it will show where it's broken. Spray all the bleeders with PB Blaster ahead of time so they come free without breaking.