need help with brakes on m54

[BBVFD]

we have an m54 used as a fire truck and are have hell with brake problems. i have changed fluid with the same it had in it silicone based. i have bled the brakes many times and even took the air pack down and looked thought it and no luck. the brake work at times lock and drag at other times and the rest of the time there are no brake at all. PLEASE HELP

 

[Westech]

sounds like you have a problem with the brakes there. Have you rebuilt the air pack or master cylinder? I would get a couple rebuild kits and do it to it. Do the master and the air pack. Use DOT 3 fluid (much cheaper) and works just as good in the 6x6's. Only thing I did different with DOT 3 is bleed a quart once a year and flush out all the water that it collects. Really no big deal, and the cost savings... well you could bleed that brakes for 10 years and still be cheaper then a one time fill with DOT 5.

 

[jcappeljr]

I just rebuilt the master cylinder on 2 of my 5 tons, it solved my brake problems.

 

[BBVFD]

i have taken the air pack out and went thought it not rebuild just checked out everthing looked good but i did find a bad seal on the little piston that has the break fluid on one side and pushes up agains the air regulator. the seals on here had one facing froward and one facing to the rear its didnt seem right but i put it back the way i found it. also need to now of it take a specail material there or will buna work with out swelling up.