My air dryer is cycling every 30 seconds and purging out the bottom. Takes about 8 to 10 seconds to seal itself off and than blows out on to the ground under the engine in 30 seconds.
Running the engine and pumped down the brakes to 90 psi and the pressure builds back to 125 and blows out and holds the 125psi while idling.
I bled the rear air tank and little to no moisture in the system.
Comments
Criticism
Concerns I need to be aware of?
Time to rebuild or replace with a remanufactured.
As Doug says above. The check valve in the dryer has gone bad.
I think it's time to have your air dryer serviced.
I replaced ours with a spin on. Cheap and only took a minute to change the last time. You do have to build a bracket and change the 12V wire but pretty easy.
Pierce
A resource that may be helpful to you. Sounds like it's time for a rebuild.
Same symptoms on mine last year. Rebuilt unit took care of it. I swear the replacement looked new not rebuilt. Jim.
Replaced with remanufacture air dryer, replaced Governor, replaced check vale on wet tank, soapy water test ( found no bubbles ) at 100 psi. Listen for sound ( no hissing ).
PSI holds steady at 135 psi with engine on while Bus is stationary. Air dryer purge is about every 60 seconds. Could this be caused by air issues in the Bendix braking system behind one of the wheels?
Is the Gus the Bus safe from damage? I am leaving Michigan to drive south to Ft. Myers, Fl to begin cleaning up damaged property after Hurricane Milton and will be dependent on the bus for everything once I get there.
The guage should show the cycle. Imho.
Drop to 110 cut in , and up to 135 cutoff?
The purge cycle is a little fast. For me. But as long as the compressor can keep up your travel should be uneventful.
But it's clear to me that you have a small issue between the dryer and compressor . Maybe as simple as a hose leak or check valve.
The brakes have a high pressure line near the axles and a brake relay valve close to the chambers. Pushing the brake pedal activated the relay valve and chambers .
You can sorta test the system by applying the brakes and watching the air pressure. It will fall rapidly and should stabilize at a lower reading. Some leaks may show up and there are miles of hoses to fault.
A very slow leak is tolerable , but a hissy leak is not .
Purging air every 60 seconds your compressor is working overtime if no air is being used. If no air leaks are found especially between governor and air dryer try a new governor set to 120psi, cheapest place to start.
The purge line might be connected to the wrong port . It should be inline with the unloader valve slider .