M939a2 CTIS wheel valve not closing due to air restriction in hub.

[Jbulach]

I have a slight air restriction in the left intermediate hub, somewhere between the wheel valve adapter, and hose fitting on the back side of the hub. This is causing the wheel valve to hang open and dump air until the tire pressure drops to around 55PSI, then it closes.
Anyone have any experience or ideas what could be causing the restriction through the hub?

 

[Andyrv6av8r]

Did you try swapping wheel valves from tire to tire or putting on a replacement to verify it's not the problem?

 

[Jbulach]

Yep, old and two different NOS valves all act the same +/-5 psi.


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[74M35A2]

 

[Suprman]

Maybe the quick release valve on the axle is clogged up

 

[Jbulach]

View attachment 719633

Have you been welding again?

That looks like what was in my cooling system, maybe some made it into the air compressor...

 

[Jbulach]

Maybe the quick release valve on the axle is clogged up

I’ve eliminated the QR valve and the hose to the hub, by disconnecting the hose from the brake backing plate while wheel valve is dumping air, still no change...