M923a2 parking brake lockup.

[maxtor]

I agree. I was talking to a guy who works on these M923A2 trucks and he says that these valves stick all the time. I said you can't really repair that valve, but they just would replace it. In the field he said that they would work that roller up and down numerous times and sometimes it would solve the issue. I will know when I remove the lines and see if air is getting up to the valve or not. Still raining here.

 

[Floridianson]

Yea NAPA make air tool oil with alcohol might try that. Think its' just called air tool conditioner. Remove the supply line and fill it up then play.lol

 

[maxtor]

Just found the problem. It is the spring brake valve. Does anyone have and extra they want to sell me. Again this is for a M923a2 cargo truck.

Thanks to Ken, he found another TM location that had the appropriate test sequence.

 

[tie6044]

Care to share that test sequence?

 

[Coffey1]

its in the TMs on page 1131 of the updated Tms that Juan posted

 

[maxtor]

As Ken said;

You need to follow the TM or injury can occur. Basically you build up air pressure and just barely crack the top line to the valve. If air is present, then tighten that connection and see if there is air on the bottom line. If not, then you know it is the valve that is bad.
Please read the whole TM, for if you do not, injury or death can occur per the TM.

 

[maxtor]

IT'S fixed.....


Here is what I did.

I removed the spring brake valve and blew into the inlet pipe, and it was plugged. I then sprayed WD40 into the three air pipes on the valve. I then used my air compressor to blow air backwards through the valve. Then more WD40 and air. Now she is back working perfectly again. It took about fifteen minutes to unplug the valve.
A big thank you to Kenm352a for all his research.

 

[Coffey1]

No problem. Juan was a Great help to the research .
Any time Max two heads thinking are better than one.

 

[Floridianson]

Well you had more than two heads thinking but whatever.

 

[Ford Mechanic]

its in the TMs on page 1131 of the updated Tms that Juan posted

Having the same issue, had been running the truck all weekend and this morning the parking brakes wouldn't disengage. Little roller on the handle flips up and down like it should, didn't have time to test anything else as I was late for work.

Does anyone have a #for this particular TM in question? I'm on my phone and the tm's don't work on it, so I'll be doing some digging at lunch on a computer.

 

[Ford Mechanic]

Worked thru lunch today and then worked late, so no time to read up anymore. But I did drain the tanks when I finally got home. Then fired it up and sure enough no more problem. So I'll put a parking brake relay valve on it anyway add soon as I figure out which one it is.