dodge mini-van rear brake problem

[racsan]

ive got a very confusing problem with a van ive been working on, its a 2003 dodge minivan, have replaced the rear brakes and wheel cylinders, bled brakes and a few days later there was a massive leak inthe system, pulled apart the brakes and discovered the wheel cylinder on the passenger side had pushed the piston out of the bore fully on the side facing the front of the van. it shouldnt be possible for it to over-extend and "blow up" but it did. thought maybe there was a spring problem as one was floating around in the drum. put a new spring kit in, checked everything, re-bled brakes and put it back out on the road again. have heard the brake light is back on again and i will be looking at it again tommarrow. dont know why it could be happening, looks like all shoes are identical, no "primary" or "secondary" specific shoe. measured the wheel cylinders and all seem to be the same length. drums were not turned, just knocked the rust-ridge off with a dremel tool. how on eart could the wheel cyl expand far enough to push out a piston and lose fluid? and only on one side? it defies all logic for me. whats worse is that its not even my vehicle and i have no idea how to explain this. you would think it would have happened right away, not a few days after the fact. any ideas?

 

[blacksnapon]

how on eart could the wheel cyl expand far enough to push out a piston and lose fluid? any ideas?

You might make sure the rear brakes are adjusted up completely. If the piston has to expand excessively to finally have the shoes make contact with the drum, it might contribute to this issue.

 

[blackhat620]

Have you measured the drums? Are they within spec, if the drums are way out of spec they may be allowing the shoes to move to far forcing the pistons in the cylinder to move to far.

Also if it is the same wheel again, replace the wheel cylinder as you may have a defective one that is hanging up internally on one piston.