Help Please

The best advice yet. Probably a "blown" pancake. The poor guy is asking how to diagnose his problem not give the state more money. Great idea you tough guys, keep driving it the next scale....how safe is that. Diagnose and fix. If your boss won't fix it...quit. Don't move it another inch.

 

And if he quits the boss gets somebody else to drive it . If the truck gets out of service deliveries don't get made and the owner pays twice as much for the repair .

 

Ok, with the truck parked and the yellow button out, (park brakes applied) there is no air to the brakes at all. If the air will not build up you have a leak in an accessory system, possibly the air suspension. I have seen leaks so bad that with the engine running at idle it will not build past 90 or so. When you shut the truck off it leaks so fast you can't find it. Sometimes the worst the leak is, the more quiet is too. Anyway, your truck most likely has rear air suspension, and some kind of cab air ride too. You may have a leveling valve blowing out. All trucks have a primary and secondary air system. Each is protected by check valves, (if they are working) so that a major leak in one system won't drain down the other. Is both your gauges dropping at the same time? Primary air really only goes to the rear brakes, dash park brake valve and the foot pedal brake valve. Secondary system is for front brakes and accessories. If only one system is dropping then we can start to pin-point the leak. If both systems drop at the same time, the inlet check valves still could be bad, but there are still some parts that get air from both systems at the same time like the dash park brake valve and foot brake valve. Or simply the main discharge line from the compressor has a hole or crack or the air drier is leaking out the bottom all the time. This kinda can go on and on. At some point, I think, you are going to have to take this in to a professional, whether your boss likes or not! Good luck.

 

Build air pressure until it pops off, turn off the engine. Have someone hold down the brake pedal and look for the leak.....like most have already said, it could be anything from the relay valve to the chamber.....either way its not an expensive fix.....however its a very very important one.

 

WOW. I can't believe what his boss said. That truck is not safe to drive the way it is.

All good advice so far. loosing that amount of air that quick has got to be a fair sized leak somewhere.

Please keep us posted.

 

I worked for a few pr...ks like that, he'd be doing himself a favor.

 

Plz do what it takes to get it fixed. write it up on your veh inspection and dont drive it till it's fixed. It is ultimately your responsibility if u drive an unsafe veh. We're not talking about a tail light it's your brakes. I dont think your employers understands the seriousness of this,and u may have to call the state DOT if u feel your job is in jeopardy for reporting it. Alot of good answers here so good luck.