Brakes Sticking on MC7

[Stormcloud]

Hi, all:

Bus had been sitting in Yuma for a month before heading to Quartzsite.

Brakes didnt seem to want to release when taking it oiut of storage. A couple of times on the brake plunger and a couple of good full brake applications seemed to clear it up.
After the rally, headed north of Q to do some boondocking. Front brakes appeared to be dragging, not releasing.
Again, a couple of brake applications and all is good (maybe).
Five days on the desert and time to come home. Brakes released normallyh, drove a bit. Had to use the footbrake a couple of times, and brakes again seemed to be grabbing.
The exhaust air from the QuickRelease Valve or E-1 Foot Brake valve sounds different also.

I'm thinking plugged exhaust ports. I cant get to this until Monday to start on it, and Im in no rush to make it mobile again. We dont leave for home for another 6 weeks.

Restricted exhaust ports? Am I on the right track?? What says the masses?

Thanks for your input!

Mark

[bobofthenorth]

My guess is a relay valve.  They're cheap - I wouldn't mess with trying to fix it.

[gumpy]

I'm with Bob. Sticking valve, or possible a sticking pedal or linkage. May just need some WD40 sprayed on it.

[bevans6]

Why do you think it's the front brakes?  Anyway, the front brakes are fed directly from the treadle valve to a QR1 valve where there are two lines out to each brake cannister.  The QR1 is a quick release valve, has a diaphragm in it that seals with pressure from the treadle valve and releases to allow air to exhaust as soon as the treadle valve pressure is released.  They are very standard and very cheap, available anywhere truck parts are sold 

If it's the rear brakes, then the relay valve has a similar quick release valve built in for the rear brakes. 

Brian

[ol713]

  Hi;
    I too have a MC-7 with a similar problem.  Every once in a while the right front brake
    would grabe. I figured it was rust and continued on. I would drive it and seemed to
    clear up.  It did not. I found new brake cans at car quest auto parts and have not
    tried them out yet.
    As for the problem of releasing the brakes,  I think your DD-3 brake cans are going to need
    attention. The problem starts out small and gets worse as you go.
    Please keep us posted.  Am still learning after 10yrs driving our bus.
                                           Merle