Brakes locking up M923A2

[jeremy turgeon]

just picked up a m923a2 on the way home the breaks where locking up when i would hit the break and wont release when you let the truck sit for about 20 min they are fine. and the green air line under the truck that feeds the breaks and they release. any help would work thanks

 

[M35A2-AZ]

I know this sounds off the wall, but make sure your vent on the front services side glad hand is open and it is working.
If there is a ball valve there open it. the truck needs to vent out the front service glad hand when you release thebrakes.
It happened to me and that was the problem.
If you drain all the air out of the truck and then air it back up does it work ok then?

 

[OilfieldRoughneck]

I know this sounds off the wall, but make sure your vent on the front services side glad hand is open and it is working.
If there is a ball valve there open it. the truck needs to vent out the front service glad hand when you release thebrakes.
It happened to me and that was the problem.
If you drain all the air out of the truck and then air it back up does it work ok then?

what he said

 

[jeremy turgeon]

went out this morning and checked the vent and it was full of sand cleaned it out and no more problem thanks you for the info guys.

 

[M35A2-AZ]

 

[jeremy turgeon]

Went out this morning to move the truck and the breaks locked again. I cleaned the glad hand and been through a lot of other valves and i keep finding sand in everything. any other ideas would be appreciated thanks

 

[M35A2-AZ]

Must be one of the check valves is not working. Look at the P2P software in the 5 ton manual area and that will help you.
http://www.steelsoldiers.com/showthread.php?79228-TM-s-for-the-939-series-trucks

 

[jeremy turgeon]

had a few valves full of sand and a few other things but the truck is stoping and going with no problems thank you

 

[dilligaf13]

A little air tool oil in the air system helps lubricate the various check valves in the M939's air system.