GearHd6

I've got a 96 Ram 2500 with only rear ABS. The brakes have been pretty terrible since the day I owned it which was in 1999 with 36k on it. They've always been spongy with not a very good pedal feel. Now the problem im having is, if I stand hard on the brakes the pedal will slowly go down to the floor and the dash brake lights will come on. There doesnt seem to be any leaks anywhere. I had to replace the steel line going from the front to the rear, the one that runs behind the fuel tank. I vacuum bleed the system and then I also bleed it a few times the old fashioned pump and hold technique. Theres no signs of brake fluid from any of the connections. Im lost, what could it be? Thanks.

infidel

Your description indicates an internal master cylinder leak perfectly.
This is commonly caused by pushing the brake pedal down further than it normally travels when bleeding the brakes or if there is air in the system.
What happens is the master travels into a normally unused area that is rusty thus tearing up the seals.
I've found it not worthwhile to rebuild the master yourself, buy one already rebuilt.
Make sure to follow bleeding instructions, the master must be bled before it's installed.

madhat

X2...... Bleed them good...

GearHd6

Ok thanks. Its got to be that because the pedal didnt bleed down prior to this.

sleepr tsi

I had to do a *lot* of brake work on my truck and it had the same spongy problem. After I replaced the calipers and wheel cyl. (and the lines to the wheel cyl.) I still had the problem. I didn't see any seepage any where but I figured it had to be the rubber lines off the rear and/or the front. I swapped out the fronts and that fixed it.

But if you had no problem before bleeding, maybe it is the master. I thought it to be just good insurance since I had replaced everything else.

GearHd6

Well I replaced the master cylinder today, samething.... The pedal just slowly goes to the floor. I cant find a leak anywhere. I can see all the lines clearly and nothings wet. I bench bleed the master just like the directions said with the 2 plugs installed. Then I vacuum bleed everything. I dont think the pedal going to the floor is air related at all. Air in the lines would just mean spongy brakes I would think.

GearHd6

The only other thing i've got on my mind is the line I replaced that runs from front to rear, the one behind the tank. It seems like when I replaced that line my nightmares started. Theres a union in the line about mid way because I couldnt find a line long enough so I used 2 lines. I had to double flare one end. When I originally installed it, the line leaked at that flare, but I tightened it more and now I dont see any fluid around there no matter how hard I stand on the pedal. Could the pedal still drop even though no fluids leaking?

~Angry Tractor~

I just replaced the same line and I have the same symptoms as you. I managed to find lines the right length so I didn't have to double flare anywhere. I do have a union in the same place you have though. I vacum bled my lines also. I'm at a loss here. I had to get on the brakes hard yesterday while I had a trailer hooked up and there was no lock up just kind of coasted to a stop. The pedal bottomed out on the floor. I got some thing weird going on here. Did you bleed your front brakes too?

GearHd6

I bled everything. Bench bled the master cylinder, vacuum bled everything and then gave each wheel a few pumps and bled them the old fashioned way. The pedal still slowly goes to the floor. I checked vacuum today, its pullin 26" of vacuum and holds it after the engine is shut off.

CrazyN8

Same thing here. When I first bought the truck, I saw the ABS light come on when backing up. A few months later, I broke a brake line (the one from the abs valve to the rear) and replaced it, as well as several other lines. That's when I started getting the sponge pedal. If you pump it up, it will pressurize the pedal, but the brakes will lose pressure. This will usually set off the abs and brake lights. Also, after pumping, if you hold your foot on the pedal, it will slowly travel to the floor.

I was hoping it was the master cylinder until I saw this post. I can't imagine it being a bad rubber line, but crazier things have happened. Could be combo or abs valve?

vzdude

Try manually bleeding the system. I've had several not bleed well with the vaccum . I have a different way to bleed than most. It works for me so......

Have your assistant set in truck. Starting at the right rear, going to left rear, right front, left front. ( one at a time! ) You open the bleeder and say "DOWN". They then push the pedal down and hold it down. Then, when fluid stops coming out, you close the bleeder and say "UP". For some reason the whole "pumping the pedal" doesn't work well for me. I like my system and it seems to work for me.

heykw

I would replace all of the rubber lines in the brake system. Good luck, keep up posted.

GearHd6

I used that bleeding system after I vacuum bled them. I had someone sit in the truck and run the pedal while I cracked the bleeders. So far nothing i've done has helped the problem. Every different thing I try gets me the same result. I think I may try replacing all the rubber lines. The right front rubber line is new so i'll do the LF and the rear line. You know every lines going to snap off when I go to undo it dont ya...?

vzdude

2 things cause soft and spongy pedal. Air in lines, or excessive movement of calipers/wheel cylinders. The rear brakes could be out of adjustment, also.....are the front rotors warped at all? If the rotors are warped, and the caliper slides aren't free ( not too many are on those trucks! LOL) the warped rotors actually push the piston of the caliper back in while you are driving, causing the pedal to have to be pushed in further to push the piston back out. Follow me? That was a long scentence! LOL I don't see where you will gain a thing by replacing rubber lines. But hey......I've been wrong before.

GearHd6

I totally understand what you're saying. But right now my main concern is why I cant stop the pedal from slowly bleeding to the floor when I hold on it. I can see every line clear as day because I have the fuel tank out and there isnt a leak anywhere. I replaced the master cylinder already and it gave me the same exact results.