Secondary Tank Leak While Braking:

[Defcon-1]

I promise I tried searching for this but there's like a million+ threads and I can't figure out which one is applicable, so apologies in advance if I'm asking a question that's been answered multiple times.

Sitting at an extended red-light, I noticed my secondary air gauge was going down little by little. I would say maybe at the 3 minute mark, it dropped below the threshold and kicked on the compressor. At the next extended red-light, I put the truck in neutral and it maintained 120 psi, but when holding the brakes, it started to leak-down (not rapidly, but enough for it to drop down a bit, as a steady decrease)

After I got home and turned the truck off, I hit (and held) the brakes and heard a slight hiss coming from the air-intake-stack. My question is, I'm not sure if this is all normal and I just happen to notice it being at a red-light for so long, or if this is something to be concerned (minorly or majorly) about.

Also to note, my secondary tank is the better tank that holds pressure 24+ hours. It does not leak (a lot) while sitting, but seems to be only when holding the brakes. I'm thinking it might a dirty check-valve / one-way-valve, but just looking for a place to start troubleshooting if anyone has any ideas. Thanks in advance,

 

[simp5782]

Got a service diaphragm leaking somewhere more than likely. One of the 10 on the truck

Maybe a Q2 valve but they usually dump massive amounts of air out the stack.

If you don't have any air leaking from the stack when the air is hooked to the service gladhand then you have a bad treadle valve.


Have someone hold the brakes or hook an air compressor to the passenger front service gladhand fitting to apply the brakes. Spray bottle with soap water and spray the clamp on every service chamber

 

[Defcon-1]

Got a service diaphragm leaking somewhere more than likely. One of the 10 on the truck

Maybe a Q2 valve but they usually dump massive amounts of air out the stack.

If you don't have any air leaking from the stack when the air is hooked to the service gladhand then you have a bad treadle valve.

Have someone hold the brakes or hook an air compressor to the passenger front service gladhand fitting to apply the brakes. Spray bottle with soap water and spray the clamp on every service chamber

That's a good copy, will report back with findings, ty Sir