Just replaced a collapsed right front brake line. The van only braked with the front left wheel and would be unstable during hard braking

With the replacement of the brake line the instability problem was eliminated but now the brake pedal is not firm. I flushed the brakes by pumping a full quart through the system. The pedal is very hard when the engine is off but when turned on the pedal sinks to the ground.

any idea what could cause this? is there air trapped in the ABS system that needs to be pushed out by engaging ABS? any tricks to bleeding these machines?

thanks for the help.

 

Do you have 4 wheel ABS or RWAL system?

RWAL and non ABS brake bleeding sequence:
RR
LR
RF
LF

I think 4 wheel ABS follows the same procedure but I may be wrong.

 

Exactly. One must bleed the rear first before bleeding the front. The lines are long for a B2500 and B3500 van. So, get two large bottles to start with.

AND if you replaced one brake hose up front, you better replace the other side as well. Having one new and one old isn't wise since the new one can really take the pressure and the old one will just burst or leak or blow out leaving you in a bad spot when the brakes are really needed.

 

There's no need to bleed the rear brakes since only the front half of the system was opened....correct?

 

thanks for the responses.

i replaced both front lines just in case. when bleeding I followed this sequence:
RR
LR
RF
LF

frankly, i am not sure if the van has 4 wheel abs and have no clue what RWAL is?? it is a 2002 3500 van, 318ci motor. I think i read somewhere that if there is no abs sensors on the front wheels(the situation in my case) then the van has only two wheel ABS.

only front lines were open, both of them.

i am trying to find out if the ABS system in this has the propensity to hold air. on BMWs, for example, if you get the air into the ABS pump the only way to get it trough is to use a special tool that activates all the valves inside the ABS pump.

thanks for the help.

 

Nope, no special tool or equipment is needed. Both ABS and non-ABS brakes are bleed the exact same way on these vans.

 

Absolutely correct. Master cylinder is separated by two chambers, one for front and one for rear. Rears don't need bleeding if nothing on the rear part of the hydraulic circuit was touched.

 

thanks for the help. i guess i will once again re-bleed the entire system, maybe something went wrong...

 

I am having the same problem, only I changed the line from the ABS block to the rear block connection, found leak in RR wheel cylinder so now have changed both RR LR cylinders and also the Master cylinder (thought it was bad but found leak and cracked line to rear) have bleed system (and bench bled new Master cylinder) enough that we've used 5 qts of brake fluid did the bleed order mentioned here.....

 

new front bearings, rotors, calipers,pads,lines and mastercylinder..2weeks ago have used 5 gallons of brake fluid and I STILL have as much air in line as ever.. could I have a bad (new) mastercylinder? or what do you suggest besides calling the junk man. I'm a pastor and this thing has really challenged my sanity... HELP !!! PLEASE... THANKS.. Ed