2006 frightliner when I build max pressure it doesnt release all at once

I have a 2006 frightliner ive put a new dryer and New govoner several months ago and its been working fine. Well then a week ago or so I some how blew all my coolant out the resivor overflow hose and over heated... Well somehow im pretty positive is my thermostats getting stuck closed or maybe water pump went out idk i replaced both because after i overheated and tried to wait tell morning add more coolant because resivor emptied out and then the resivor would stay super cold and so would top hose going to radiator... Well after they replaced water pump Nd thermostat now my air system isn't purging the air off right. Instead of one solid sphh! Every so often it goes sssssssssssspppppppppppppphhhhhhhhhhhhhhhhhhhh for about 20 seconds about once every 2 minutes sitting at idle. It starts doing it at the normal psi and it drops down to the normal psi it just takes a super long time to purge.... Also problem is when im going down the road at 75 the airs building faster then it can release so im having to hit breaks to release pressure

 

Im pretty positive on the compressor only thing on tank really is pressure valve

 

Im sorry let me say again. I had someone replace that because i didnt know what I was doing? I do what i can?

 

Thankyou very much and will send post ASAP because having to hold the seat air gun out the window and tap on the breaks is annoying as hell

 

the govoner is on the very front of the tank