need some help. brake diagnotics from simple service gone wrong

1999 dodge dakota RT. 2wd, front disc, rear drum, ABS.

problem: pedal going to the floor despite bleeding 3 quarts of fluid through it. 

history: the truck had calipers, front hoses, pads, rotors, drums, wheel cylenders, shoes, and hardware when i got it from my best friend for my brother. he hdnt swapped the rear brake hose or master cylender. my brother has said since he got the truck that the brakes felt mushy to him, with slow pedal return. weve bled the brakes a few times with no change. 

today, we swapped the rear brake hose that showed no signs of any issues. we also cleaned, deburred, and lubed the front calipers and slides. then proceeded to bleed 3 quarts of fluid through it. engine off , the pedal felt great. we had no air coming out at all, and nice clean fluid at all four corners. engine running, pedal goes to the floor. no amount of bleeding has changed that. i have tapped lines, rerouted the rubber hose, tried gravity bleeding in addition to the two man bleeding, tried bleeding the rears with the e brake engaged and not, tried driving to activate abs (couldnt). cannot make a change. 

im berkeleying out of ideas. i got no idea why i lost pedal, or what to do to get it back. it seems like theres gotta be air in the lines, but there cant be. pedal wont pump up running like it should if there was air. 

so, hwo do i fix this stupid thing? what am i not thinking of?

How does it drive?

Our 99 suburban has good strong brakes but because of GMs stupid, overboosted system and ABS, I can push the pedal to the floor with the truck running but not moving.

Engine off, it builds pressure like any normal system.

If it were a GM product, I'd suggest checking to see if the shuttle in the proportioning valve was jammed to one side or the other from bleeding. I've had that happen before.

No idea if Dodge uses a similar system.

Any sign of turbulence in the master cylinder reservoir when the pedal is pushed? It could be bad even though it moves fluid during bleeding.

Did you make sure the rear brakes were adjusted properly before bleeding?

I'm thinking that if there is too much clearance you may not get good bleeding on the rears. 
 

ShawnG said:

How does it drive?

Our 99 suburban has good strong brakes but because of GMs stupid, overboosted system and ABS, I can push the pedal to the floor with the truck running but not moving.

Engine off, it builds pressure like any normal system.

If it were a GM product, I'd suggest checking to see if the shuttle in the proportioning valve was jammed to one side or the other from bleeding. I've had that happen before.

No idea if Dodge uses a similar system.

We used to call that the Chevy Blazer Syndrome since S-10 Blazers were notorious for that.  Absolutely horrible pedal in the shop, feels great on the road.

My question is, does it have a good pedal when you spike the pedal but a sinking pedal when you apply it gently?  That's a bad master cylinder.  Spiking it pushes the seals out hard to the bore and makes them seal, gentle braking allows the seals to bypass.  New does not mean good!  If you only knew how many defective brake calipers we get...  hell last month we had every single Honda Accord caliper be bad, five different pairs from two different suppliers.  

I have had a few Mitsubishis with bad ABS units that would feel just like a bad master cylinder, but it's a leaking dump valve in the ABS unit.  This won't matter if the engine is running or not.

I has a similar issue and it was the master cylinder...

Pete. (l33t FS) said:

ShawnG said:

How does it drive?

Our 99 suburban has good strong brakes but because of GMs stupid, overboosted system and ABS, I can push the pedal to the floor with the truck running but not moving.

Engine off, it builds pressure like any normal system.

If it were a GM product, I'd suggest checking to see if the shuttle in the proportioning valve was jammed to one side or the other from bleeding. I've had that happen before.

No idea if Dodge uses a similar system.

We used to call that the Chevy Blazer Syndrome since S-10 Blazers were notorious for that.  Absolutely horrible pedal in the shop, feels great on the road.

 

My question is, does it have a good pedal when you spike the pedal but a sinking pedal when you apply it gently?  That's a bad master cylinder.  Spiking it pushes the seals out hard to the bore and makes them seal, gentle braking allows the seals to bypass.  New does not mean good!  If you only knew how many defective brake calipers we get...  hell last month we had every single Honda Accord caliper be bad, five different pairs from two different suppliers.  

 

I have had a few Mitsubishis with bad ABS units that would feel just like a bad master cylinder, but it's a leaking dump valve in the ABS unit.  This won't matter if the engine is running or not.

Everything he said and when you were bleeding the brakes did you push the pedal to the floor by any chance?  Might have beat up the master cylinder while bleeding so much.

If you accidentally ran the master dry, might need to bleed that. 

Master cylinder is either leaking into the booster or bypassing.

We never ran the master dry.

However, we have no brakes when driving. Kinda sorta slows, but not really. 

Ill have to try spike vs normal application tomorrow, as well as look for turbulence in the master. But im wondering now if the spongy feeling hes been reporting that i haven't been able to fix has been a failing master that ive missed....

Maybe try pulling the ABS fuse to rule out anything that system could be doing differently running vs. off. I haven't yet seen a power-dependent ABS failure but it could be worth a try just to be sure at this point.

I'd bet the master got hurt during the bleed--somewhat common for the increased range of motion to cause issues with an old master. 

Got a master cylinder on order. Seems logical, and likely based upon y'all response. 

Thanks everyone. Here's to hoping!

I was gonna vote booster but master is easier to R&R

Make sure the rear wheel cylinders are adjusted correctly. I had almost the exact same thing happen on my Chevy C2500 and it about drove me up the wall. Turned out when I installed new rear brake hardware I left it with too much clearance. Difference was I never got a firm pedal but it's worth checking. Tightening up the brake shoe adjusters until the shoes almost made contact fixed it. 
 

it also might be the master, of course!

I had a similar situation with a car. After attempting brake bleeding numerous times, we replaced the master cylinder. Still the same solid pedal engine off and very soft almost to the floor engine on. We pulled all 4 wheels and inspected the pads and shoes installation. We found a brake pad was not installed correctly with the steel backing binding on the caliper. Engine off with no booster assist the steel backing did not move. Engine on with boost the steel backing actually flexed and bent. Other than that, I have found front calipers installed with the bleeders on the bottom, but you never get a solid pedal. Always bleed the master cylinder first, which, I am sure you did.

As for drum brake adjustments. 

1) Crank the adjuster all the way up until the shoes are tight against the drum. Tap the drum a few times with a mallet and re-tighten if necessary. 

2) Back the adjuster off until you can turn the drum with just a slight drag.

Only cranking the adjuster out until the shoes barely touch is a good way to get uneven application and a car that pulls left or right. Tightening things up moves everything into it's operating position after you've moved it all around doing the brake job.