Brake pedal goes to floor

[Chick]

I have a 1998 Dodge 2500 with V10. I got in it to go to town, and the brake pedal does to the floor, Checked the whole truck and could not find any fluid leaks. Bought a new master cylinder, bench bled it, installed. Bled it on the lines, and the pedal still goes to the floor. Not losing fluid. Back brakes are adjusted. What is going on? Proportioning Valve? Anti-lock?? Thanks!

 

[SYKRAMMAN]

Brake booster maybe.

 

[MADDOG]

Brake booster maybe.

I'd have to agree with SYKRAMMAN...if that diaphragm in the booster case goes bad, or you don't have sufficient vacuum to the case, the brakes will pretty much be dead.

 

[Chick]

The brake booster just makes it easier to depress the pedal. This pedal just goes to the floor. Once it makes it to the floor, the brakes will stop the truck.

 

[SYKRAMMAN]

Correct but like maddog said, if the diaphragm is shot, you’ll loose vacuum and result in sponge brakes.

 

[Chick]

I don't have sponge brakes. The pedal just goes to the floor. If you pump it, it will stop about 1" from the floor. When it goes all the way to the floor, it will stop. I am sure it is either the proportioning valve or the ABS, but don't know how to diagnose which one it is.

 

[SYKRAMMAN]

The only two things that give your pedal pressure are master and booster! If it was proportioning valve then it would pressurize fluid to wheels at different pressures causing lockup on said wheel/wheels but you would still have pedal! If it’s the abs, it would be the module or wheel sensor but again you would still have pedal, maybe you got a faulty master, I’ve had it happen right out of the box. If I’m wrong, somebody will correct me. Maybe you didn’t get all the air out, maybe there is a tiny pinhole you can’t see. Could also be a vac leak somewhere, jmho.

 

[Chick]

I found this. It points to the RWAL.

http://www.federalmogulmp.com/en-US/Technical/Documents/RWAL False or Dropping Pedal.pdf

 

[SYKRAMMAN]

I learn something new everyday, great research, keep posted on progress and good luck.

 

[Rado]

I found this. It points to the RWAL.

http://www.federalmogulmp.com/en-US/Technical/Documents/RWAL False or Dropping Pedal.pdf

Good find PLEASE update us with your results ! Also WELCOME to the group !

 

[golfcarr]

Did you solve your problem? If so, what was it ???

 

[dodge dude94]

Did you solve your problem? If so, what was it ???

Rather than adding onto an existing thread, I would highly suggest you start a new thread in your specific forum: https://www.ramforum.com/forums/3rd-gen-2002-2008.43/

You'll have better luck that way.


Truth be told, 9 times out of 10, a brake pedal that drops to the floor is the master cylinder. Rarely it's a hose or line, those you can easily spot as they leak.