Brake Issues...

[CumminsPower59]

Ok, my 92 has been making a hissing noise when I am not using the brakes and goes away when my foot just begins to press the brake pedal and comes back when my foot leaves the pedal. The brake pedal is very firm half of the time, the other half, it darn near goes to the floor. The anti-lock light is on also. I have bled the lines out, and have nice, clean fluid in it. Where would be the best place to start? I have thought about bypassing the RWAL module, but I didn't know if that would take care of the hissing noise. Any help would be greatly appreciated, thanks!

[ellis93]

The noise you hear is probably vacuum escaping around the boosters shaft inside the truck. It would be a bad booster. Whenever they go bad though its usually accompanied with a very hard peddle that does not give way, so I don't know about that one. Yes go ahead and rid your truck of the abs accumulater. You'll live happier without it.

[CumminsPower59]

I have replaced the brake booster, that fixed the hard and soft pedal issue along with the hissing noise. I also by-passed the RWAL accumulator on the frame rail. Brakes bled and the resivoir is topped off. I now have little braking action until the brake pedal is 2/3rds on it's way to the floor, then it grabs good. Now, where should I be looking next???

[ellis93]

Rear shoe adjustment.

[oldestof11]

When you replaced the booster, did you replace the master cylinder?

If not, there is a procedure to adjust the brake rod inside the booster.

I did all new lines, new front pads, new brakes in the rear (shoes, drums, cylinder, hardware. All 1ton stuff), new MC, adjusted the rod. I had brakes from the time my foot just barely touched the pedal to full lock up 1/2 way down. I was then able to spool the turbo to 25lbs without breaking the tires loose. Once let go however, the tires roasted!

[CumminsPower59]

ellis93, That is what I am thinking...

oldestof11, I replaced only the booster, the mater cylinder was in pretty decent shape, no leaks at the rear of it or anywhere else. When I installed the booster, I noticed that the pedal was out of adjustment as the pedal rod wouldnt contact the brake light switch, but I couldn't find where to adjust the rod externally...so I just pushed the switch in all the way untill it made contact with the pedal rod. Is there an internal adjustment somewhere?

Thanks for the help fellas!

[ellis93]

The rod that you'd adjust is inside the booster and pushes on the master. You'll have to take off the master to see it. I constantly forget about it.