M1088 Trailer Air Supply

[CajunCowboy]

I was having issues getting air to any of my glad-hands when supplying air to the trailer air system. I would push in the red trailer air supply knob and get a small pressure build and thump but still no air. if I pulled the manual air lever down I would hear air exhaust but noting at the glad-hands. The parking brake air has always worked fine and with help from a buddy we noticed when we pull the parking brake we could hear the system fill but when pressing trailer air supply in it was just a quick thump. so this led us to check the valve at the trailer air supply valve that the red knob is connected to. I pulled it out the dash and couldn't figure out how to get to the back spring but shot some WD-40 in there and reinstalled since it was getting late. Luckily the lubrication was enough to break loose the seized plunger enough to get some air into the trailer brake system.

Also with the M1088 there is a three way valve at the 5th wheel air supply to the service glad-hand and the emergency glad-hand. I believe the three functions are Closed, Fithwheel, pintle/Front tow supply.

I am in the process of looking up the part number for the Trailer Air Supply Valve to replace since I couldn't get to the back plunger that was seized. even though its working now id like to get it fixed right so I don't have any issues down the road. Just thought I would share this to help out anyone else that may be having issues down the road.

Take it easy on me im new to this stuff so don't take my words to the bank but just thought it could be helpful info to someone one day.

 

[CajunCowboy]

Here is the plunger half of the valve assembly that I couldn't figure out how to disassemble. Let me know if you have any pointers

Thanks

 

[NDT]

Sometimes insects build mud nests inside the glad hands or way up in the coiled hoses.

 

[Ronmar]

You are using both controls right? Park air controls the trailer control air source…

 

[CajunCowboy]

You are using both controls right? Park air controls the trailer control air source…

Yes, it started working after I lubricated the trailer air supply valve and reinstalled it behind the dash. still want to replace that part though bc I can't figure out how to get the rear plunger shown in the picture out. But I do have air working now.

 

[CajunCowboy]

You are using both controls right? Park air controls the trailer control air source…

I bet that happens a lot. darn mud divers back home in Louisiana would get into everything. It started working after I reinstalled the valve and got the three way valves in the right directions!

 

[Ronmar]

Yea there should be screens just inside the glad-hand openings to prevent insect intrusion…