Sealco 110500 slow to set spring brakes

Hey guys I had another thread for this issue because I thought it was a trailer problem but I now believe it is an issue with the valve. I have had 3 different ones on over the years all have the same issue. My 53ft dry van has a sealco 110500 spring brake control valve or quick release valve which ever you want to call it. When I pop the red valve in the truck to set the trailer brakes it will blast out air and set the brakes about 75%. Then it will slowly release air from the red gladhand until about 10 mins later the spring brakes will be set 100% and the trailer will be unmovable. I checked up and down the whole trailer. No kinks, no clogs, nothing. Everything else works as is on the trailer. Brake canisters aren't that old, slack adjusters work as they should, brake pads are almost all new, everything is adjusted properly. Literally the one thing that doesn't work is this dumb valve not releasing all the air at once to set the spring brakes for parking. Any ideas would be greatly appreciated. I am super annoyed with this #### valve at this point, I have spent all day trying different things on it, had it on and off and apart and everything. It still does the same old thing. The only reason I care is because several warehouses i go to I drop the trailer and yard trucks put it in docks. If they come before 10 mins to grab it they do a tug test then they call me and say my trailer has "no brakes" which I obviously know isn't the case but they don't really get it when it comes to how the brakes function. Needless to say I am ANNOYED. So send me some suggestions or ideas. Thanks in advance.

 

After I set the parking brake it releases enough air to partially set the spring brakes but yes i do have slight air pressure at the red gladhand after they are set. It will slowly drain out of the red gladhand for about 10-15 mins. I believe it is draining the trailer tank. When it is doing that slow release. Air bags stay aired.

 

Not all of it. Just the last portion that doesn't exhaust immediately when I set the parking brakes. And it comes slow from the gladhand like 10 psi if I had to guess.

 

Oh shoot I think I get what you are saying now sorry man. It has been a long day. I have air back feeding slowly from the trailer gladhand. The truck has nothing coming from it once I set the brakes.

 

Yes sir I have a new one on right now.

 

Yes there is. I have a blue service air line going to it for controlling the brakes when in service.