prentice, glad i am not only one. i found changing out cyl the only remedy. still ,cyl cost about 300.00 and the kit about 100.00. i suppose mico-loc is happy selling a new cyl every 18 mos. mike aloris

Hello Mike, I ran into this problem about 2 years ago on a C500 8000# unit. The Brakes are inside the differential......not a fun job to repair. I replaced the master cylinder 3 times since then and found bleeding the system a nightmare, also replaced internal assemblies.

ed t, the machine in discussion has the oem prk brk mech in place +in working order. mico brake is the vendor of the master cyl in question. it is conventional in appearence, but is a 2 stage volume unit. the 1st stage sets the pucks and inching cyl, using very little pedal travel, 2nd stage is small volume with light pedal effort. when working,best of both worlds. in this case, every 2 yrs or so, the master holds a residual press necessitating replacement. question stands, has any one else run into this? what say you? mike aloris

a mico brake lock should only be used as a temporary holding assist, and not an over night parking brake, and the operator should be instructed as to the proper way to set and release the brakes, the mico-valve should only be turned on OR -off- with the operator applying stopping pressure to the pedal, and not just slap the handle to the released position, to prevent the damage you are experiancing. (also note that the cam on the handle that pushes the plunger is not at it's widest spot with the handle to the fartherst it can move, but it should be at a right angle to the valve, but can move further, depending on how it is mounted.
For MY money, I get rid of the Mico-lock, and fix the parking brake this truck came with from the factory.