ctis air flow sound in the hubs

[Machineman]

I'm having an issue with the tires leaking down M923a2. When manually filling the tires I hear the sound of air rushing in the hubs. The air rushing sound lasts for about 10-20 minutes. Last summer I would also hear this noise after shutting the truck down. Is this a normal sound, are the wheel valves in need of a rebuild? I've seach the forums with no luck. Any ideas would be appreciated.

 

[Alexsha]

Remove the ctis wheel valve and put a Schrader core in the stem. If the tire leaks down you have a leak in the split rim or the tire. If it doesn't leak, put soap and water in a spray bottle and start looking for bubbles.

Things that leak:
O-ring in the split rim
(Big) nail in tire
Stem going into wheel
Ctis line attaching to stem
Ctis wheel valve
Line attaching from hub to ctis wheel valve

 

[Machineman]

Just painted the wheel and put new o ring and stem grommet in. Still hear a air flow sound rushing into the hub. I will disconnect the ctis line in the morning. Can a bad ctis wheel valve back flow into the hub?

 

[Alexsha]

You should be hearing the air releasing from one of the 3 quick release valves. My front driver side wheel airs down because the wheel valve diaphragm is shot. I have a replacement on the way.

Check the duckbill on the quick release for the wheel in question. If air is coming out, the diaphragm in the wheel valve could be the culprit. As it's airing down, you could try taking the screw out of the wheel valve cap and use a small screwdriver or similar to put pressure on the diaphragm cup. See if it seals.

If the air is just coming out the wheel and not the quick release, your oring might not have sealed. Did you clean the oring groove really well? I think most people sandblast that area. There should be no rust where it sits.