Sleeper air bags

[earnies2]

(07-27-2022 )DVT873 Wrote:  Does the line from the leveling valve go to one of those solenoids? Would have to be the blue line. What does the label read on the solenoid that the blue line is going to? Post your VIN and i might be able to find the air schematic.

Yesterday we had an air ride suspension that wouldn't go up. The solenoids were bad. I could see green powder in the air port. Did not cut it open but it looks like moisture got inside and corroded the copper windings on the solenoid.

Don't know why Nav would plumb that way but they do many mysterious things.

The line is teed into the line for the valve block. Everything in the block works fine.
Here is my vin 9C137926

[Rawze]

On my prostar, things like the cab air bags, etc .. are on a line, fed by a solenoid, that only gives pressure when both tanks are above 90 psi...

It could be that the solenoid, or the solenoid distribution block itself is weak or going bad, not allowing full pressure thru it.

Those distribution blocks are also plastic and tend to go bad about every 6 or so years .. especially up north where ice builds up in them and cracks them, making all of the out pressures weak.
http://rawze.com/forums/showthread.php?t...75#pid3975


It is hard to tell if that block is leaking because it will stop leaking as soon as one of the tanks drops below 90 psi.. and all the faint hissing stops. Someone has to run the truck and build the air all the way up to 125+ psi for both tanks.. then turn the key-switch off.. only barely long enough that the engine stops running, then right back into the on position, so that all the systems stay active without the engine turning. Then jump out real quick and listen for hissing, air leaks, etc. right away before the air bleeds off down to 90-psi.

It can be the fan clutch leaking.. the distribution block for the solenoids.. an air bag, a valve, hose.. etc.etc.etc. - Leaks that cannot be heard while the engine is running, and that only happen above 90 psi.

Also if your air-dryer-regulator is going bad, you will get less pressure than 90 psi. Air dryer-regulator is cheap compared to the compressor or that block.. so that is the thing to replace first if it is more than 5 or 6 years old, along with checking for leaks like mentioned above.

[earnies2]

(07-28-2022 )Rawze Wrote:  ...
Also if your air-dryer-regulator is going bad, you will get less pressure than 90 psi. Air dryer-regulator is cheap compared to the compressor or that block.. so that is the thing to replace first if it is more than 5 or 6 years old, along with checking for leaks like mentioned above.

Whare is the air dryer regulator. That's not the governor is it?
Both tanks fill equally and I only loose air at night down to 90psi I am always looking for leaks and have changed a bunch of push fittings.

[Rawze]

(07-28-2022 )earnies2 Wrote:  ...
Whare is the air dryer regulator. That's not the governor is it?
Both tanks fill equally and I only loose air at night down to 90psi I am always looking for leaks and have changed a bunch of push fittings.

it looks like this...



Like I said.. leaks that only happen above 90 PSI.. can usually only be found while the pressures are above this ...+ the key-switch in the dash has to remain on but the engine not running.

Someone has to run the truck and build the air all the way up to 125+ psi for both tanks.. then turn the key-switch off.. only barely long enough that the engine stops running, then right back into the on position, so that all the systems stay active without the engine turning. Then jump out real quick and listen for hissing, air leaks, etc. right away before the air bleeds off down to 90-psi.

[marek4792]

I would test the circuit by simply getting an air pressure gauge with a push connect fitting on it, and plumb it to the leveling valve circuit to see if it achieves and holds full pressure. If pressure is good then T it off to the airbag circuit after the leveling valve to see which bag is bringing it down. Not all airbag leaks are audible or as detectible by the soapy water test. Try this to narrow it down atleast.