M35a3 air psi problems

[HFDm715]

our Fire dept m35a3 developed an air psi problem last night, took it out for a ride and it lost air psi, brought back, crawled underneath, and found thatwhile running it has air leaking out of the bottom of the dryer, not a large amount, and when I block the hole with my thumb, it still doesn't build air, does this sound like an unloader problem, or a dryer problem, it was working fine minutes before, had built pressure on the gauge, popped off when it got to psi, and then just stopped working.

any thoughts?

Thanks

Duane

 

[Jeepsinker]

Is the pop off valve stuck open?

 

[Bowtie70SS]

My air hose that I keep on the hook behind the passenger seat had the lever stuck on and was leaking air. Can you hook up a alternate air source and feed it air under the dash so you can look for the leak with the truck off?

 

[RedbeardTheZombieHunter]

Check that pesky main air valve in the air packs! No air building and locked brakes are the dead giveaway. Also make sure the valves on the gladhands on the back of the truck are securely closed.

 

[welldigger]

You should also check the air priority valve on the air tanks. This device can prevent full pressure build if it is stuck closed. It looks sort of like a pressure regulator.

 

[AnonymousOne]

Also make sure the valves on the gladhands on the back of the truck are securely closed.

Gladhand leak was an issue for me. The on-off valve for the gladhand was frozen open so I had to replace the rubber gasket in the gladhand along with the steel cover. At some point I will get to replacing the on-off valve but not any time soon.

 

[HFDm715]

took the mainline off the compressor and ran it, it has some air psi, but not a lot, talked to an airbrake place we deal with at work and he gave me a head maintenance kit that comes with the valves and gaskets, he said 99 percent of the time that will fix the problem, also got a dryer kit from them since we used that truck during sandy to evacuate people from the jersey coast in salt water. keep everyone posted

Duane

 

[Bowtie70SS]

Take some pics please. What about the intake filter? Is all of that free of obstruction?

 

[HFDm715]

well, I rebuilt the air dryer, installed it, and started it, the truck instantly built air, and functions fine. so at this time I have no need to rebuild the head on the compressor, I thought the dryer was bad, because when I took the supply line off it, air came out like I was taking a line off an air tank, but the out line had no air. I guess the salt water had gotten into it and clogged up the filter. also installed a new regulator for the steering, because I had bypassed it when it broke on advice it would steer better, which it did, but in the woods on a fire call, it would use too much air maneuvering. so now I have to fix the tach that decided to stop working last week. if anyone would like the number for the compressor kit, I will post it on hear when I go to the firehouse and read it off the box.

Duane