June 2011, twice, starting downhill after long uphill on Hwy (~60mph), pedal went to floor, then pumped up and worked normally. Took it to usual shop, they could not repeat the problem, nor did it repeat again until ... early Oct. This time, pedal went to floor then would pump up, every time I needed to stop. This was around town, all terrain, all speeds, all intervals between braking. Usual shop too busy to get to checking, took it to "2nd usual" shop. They said it needed new rear drums and shoes. Did so, still the same problem. Tech there said "all is normal." Huh? Pedal goes to floor then pumps up ... sorta ... and that is "normal"? Took it to usual shop, tech did a quick check, said "definitely the master cylinder" (which is what I thought from the beginning), but they were still days away from being able to get to it. Went back to 2nd usual, at my insistence they put in a new master cylinder. Now, though brakes are more constant and predictable, the pedal is still way too soft; the tech says "good pedal." Not even! Spare me from riding with that tech. Nothing to indicate any problem, no warning lights, no ABS light. 179,979 on the clock when the work was done.

Any ideas out there about what needs to be looked at? Van is in generally good shape, preventative maintenance being the habit here.

 

Pedal is spongy or too much travel until they apply and then the pedal feels ok from there?

 

Generally, yes. Last couple of days, travel and feel is now "normal" after doing a stop or two. Still, this is quite different than the van has been since we bought it three years ago. Never had a soft pedal, even at start-up, which is still occurring.

Is there some part of the braking system that has flexible connections that could expand and contract, that is, that is becoming marginal and ready to fail? Or, is it possibly something in the ABS system?

After the new master cylinder, it has certainly improved, but still questioning it because pedal is not back to where it was before this all started.

 

On some models the push rod for the master cylinder is adjustable. Do you know if your master cylinder booster has a rod that can be adjusted?