Dash valves

I apologize, Dino Soar, Freightliner a good truck too. Reason I say that about the brake valves, Freightliner seemed to use those cheaper valves, like IH, the 2 in 1 deal, and had the smaller, thicker buttons, unlike Pete and KW had the individual ones, with the thinner, bigger buttons, that some people would break the corners off. I never could understand how someone could break those, but just seemed like better units. And does anyone remember the "mystery" 3rd blue or black buttons on older trucks? Sitting is the kiss of death for the air system. Did you check the 4 way valve? Do they still have those for the drive axles brakes?

 

Personally I would go with genuine Bendix and not have the hassle of re-oring the original. The brake system is nothing to cheap out on. If it's leaking with brakes set out of the stem of the nobs it's more than likely mv3 dash valve is bad. Sometimes you can wiggle the buttons to get them to stop leaking for a little.... Considering air leaks are a DOT infraction

 

If you haven’t already removed the complete valve. The reason everyone suggests to just rebuild what’s there is because it is the biggest PITA to unthread every one of those air lines on that old FLD cab. When they updated to the push-in style fittings it got easier. But you’ll find with your era of cab, with the never leak brass fittings that you won’t be able to find a short enough wrench in your tool box..... and you’ll find every sharp object in that dash with every knuckle you’ve got!!!

 

it might be one of the air line connections leaking..

 

When I bought this Truck, the dash valve was leaking. It was late Saturday. Couldn’t find one.A Shop gave Me a like new one replaced under warranty, for free. I changed the guts of it into mine. About a year later It leaked, like Boxcarr said, must be the plastic housing worn out. Replaced the whole thing. Big PITA. New one only lasted 2 yrs. Replaced it again, had an even harder time with it. Broke dash, threw my back out for a couple weeks, still have numbness in thigh and toe, 7 yrs later. Since then, I watched a Guy change one, He cut the lines, and used quick connects. I don’t care for quick connects, but compression fittings/ ferrules could be used. Would make the job easier, especially since like Working2 party said. Hard to get threaded nuts/ short lines on, especially if you have to change it out again, like I did.Saves time and aggravation. You could try, taking it apart, the 4 screws on front, while leaving the body mounted in dash, and coat the o rings with brake fluid. Put it back together. Brake fluid will swell o rings up, buy a little time. The second time mine went bad, it was leaking progressively worse, had to run a ways to get the part. Barely made it. Might want to get a new one soon though, since it will be a temporary fix, at best.