frostytj

1997 Dodge 2500 4x4 4 wheel ABS, disk fronts, drum rears and hydraulic assist brakes.

I am having an issue with a soft brake pedal with more travel than normal and very slow return.

Front pads were in need to changing and during the process I found a stuck/frozen caliper which had wore out the inner pad on that side. I replaced both calipers with reman'd units from the auto parts store and put in new Hawk pads. The front lines were replaced during the last brake job as was a single caliper. I should have replaced both at that time but I didnt, live and learn I guess.

Decided to do a fluid flush so I went to bleed the rears and found a frozen bleeder screw in one rear cylinder. Swapped out both rear wheel cylinders for GM 1 ton units which is what I was running previously. Also had to replace one section of hardline on the axle from the T to the wheel cylinder.

Went to bleed the brakes and did so all the way around without any air or so I thought. Took the truck for a test drive and the pedal was extremely low, soft and had slow return as well as the ABS activating when you tried to stop. Truck takes to much distance to stop and feels unsafe. Checked for leaks all around and found none.

Fast forward to today and I went back out and bled the crap out of all 4 corners and flushed a whole lot of fluid through the system. Nice clean fluid was flowing from all corners with no air that I noticed. Took it for another spin with the same results.

The truck stopped fine before although it had slightly stiffer pedal feel than I thought it should. That was probably due in part to the stuck caliper. When bleeding the pedal did travel to the floor for the most part so in theory it probably moved into the area that might be rusted and could have torn the seals. But when I press on the pedal there is no creep like I thought should happen if the seals were bad or there was an internal MC leak. Also the last brake job we bled them the same way without any issues.

I recently pulled the vacuum pump and power steering pump to replace the seal and rebuilt the vacuum pump. I'll be tearing back into it as its still leaking. I had planned on swapping out the steering pump at the same time as I have one to go in and I think the old one is worn where the seal rides which is what is causing my leak even with a new double lipped seal.

Anyway I am at a bit of a loss as to what the problem might be seeing how it was working prior to me changing out the brake parts I just did. I went ahead and ordered a new MC and hydraulic booster and suppose I'll swap them out one at a time to see if they fix the issue unless someone has any other ideas or suggestions on what to try.

Yes I know I just wrote a novel. Thoughts, suggestions or ideas?

Junk Man

I'm fighting the same issue on a Mercedes diesel with ABS. Be sure to bench bleed the new MC. You don't want air in your ABS. Making a power bleeder may help get the air out. I recently changed my Ram MC & didn't have any problem. Check the FSM to see if ABS requires anything special.

I've put over a gallon of fluid through my Mercedes system & still have air. Very frustrating. I think the ABS may not be activating & therefore holding air. I'll talk to a MBZ Master Tech on Monday. It ain't rocket science but is a pita.

SIXSLUG

Sounds like an air issue to me, too.

frostytj

I have a pressure bleeder I made for my Jeep but I need to get an spare cap to set it up for the truck.

Its my understanding that you dont need to do anything special to bleed the ABS stuff when doing normal bleeding. You need to push in or pull out a pin if you use a pressure bleeder.

I did find a new "speed" bleeder setup using a balloon, string and some plastic tubing that has worked nicely so far.

I'll try to grab a cap from the junkyard to use with the pressure bleeder and see if I can get any better results with that.

For the record I havent replaced the MC yet nor did the reservoir run dry when I was bleeding the calipers and wheel cylinders. Also the bleeder screws on the calipers are facing up.

frostytj

I took the shotgun approach and it appears to be fixed. Need to do one more bleed job to double check but it'll almost put you through the window now.

I ended up replacing the MC, hydroboost and steering pump last weekend and got it bled tonight. All said and done I installed the above plus rotors, calipers, pads, rear wheel cylinders and one hard line. Just for what should have been a simple rotor and pad change. Most difficult time I've ever had with brakes on any vehicle I've owned.

I'd like to know what exactly fixed it but alas that is not going to be the case.

Junk Man

I will never install a master cylinder without a full bench bleed again - even on an old car that per FSM doesn't need it. Will also use my pressure bleeder. Will enlist aid of a friend to pump the brakes as necessary.