First we had dragging front brakes. Changed the M/C - no more dragging but now we have a new problem - no pedal. All the calipers and wheel cylinders are new, new (not a reman) master cylinder and we also got another used rear ABS and prop valve to try....Still no pedal. We tried taking the valve out of the prop the other night and we got a big bubble of air....Bled it again and had good brakes. He drove it to work the next day and it was fine, went to leave for home and the pedal went right to the floor again. The dealer hasn't been any real help as they didn't have any answers. Anyone here have the same problem....He's got $1200 in new parts on this truck in the last 2 months (it's his first Dodge he's only had it for 3 months)and if it doesn't start to drive trouble free for a little while it's going up for sale. The little thing runs and drives good and the body is decent but this brake issue has me want to run it over with my diesel F250 4x4...LOL[/align]

 

It sounds like you're havingthe same problem as I am with my '94 4x4. I don't know a lot about the brake system on these trucks but I'll just tell you what's happening to me. When I bought the truck 3 months ago my brakeswere VERY spongy and thebrake and ABS lights were on.The lights would flicker on and off when I stepped on the brackets. I checked the brake fluid and it was low, so I added more. The brakes worked great for a little while until I lost more fluid. I put the truck in park and stepped on the brakes a few times to build up pressure. When I got out of the truck I could see fluid leaking from the rear right wheel area. Maybe you just have a fluid leak? I'm going to take my truck into the shop tomorrow so I'll let you know what I find out.

 

I have no fluid leaks or fluid loss....Just a soft pedal...I'm going to bypass the rear ABS valve and see what happens.

 

Does the pressure come back up after you pump the brakes? At first I was going to say maybe you just need to adjust the rear shoes to make sure they're tight against the drum, but you said at one point all was fine. Was it fine without pumping the brakes, or did you still have to pump...even once? If things were really fine one day, then not the next, obviously air is getting into the system somewhere. If air is getting in, then you might be able to force enough fluid (or even air) out to notice. First off, check the COMPLETE system, from M/C to all 4 wheels and check for signs of moisture (ie. stains), especially at or near the connections. Did you replace any lines? If not, maybe one of them is rusted thru somewhere. When the brake system is charged, try applying pressure and holding it...how long does it last before losing pressure? Check for leaks after doing this. Good luck...let us know what you find.

 

If the engine is off -you can pump it up hard as a rock in 2 pumps and hold it until the cows come home - no creeping down. As soon as you start the engine it goes right to the floor....I think the new master cylinder is bad and is bypassing internally with the power assist from the brake booster. You can pump the pedal with the engine running, it will build up a little but still doesn't feel right.

All the steel lines are new in the last year. The flex hoses look fine. No leaks to be seen as we have bled this thing so many times everything is covered in brake fluid.

 

Hmm, in that case, I'll agree with you and say the MC has a problem somewhere. Either something was missed during the install, or it's bad.