Paccar MX BPV actuator exhausting

So I'm trying to get this truck back on the road after it's been sitting for five months or so. I was chasing air leaks all over and ended up finding that the exhaust back pressure valve actuator is dumping air out constantly(at least at idle) from it's exhaust port. I'm not sure when it should be exhausting so before I replace it(dealer wants to cut me a deal at $670 down from $850) I'd like to make sure that I'm doing the right thing.

From what I understand the BPV is supposed to close when the engine is cold started to assist warmup. Would this cause the actuator to exhaust? Although, as I type this, I recall that it continues to exhaust after the truck is shut off. So I'm guessing it is stuck. Is there any chance that an erroneous signal is causing this?

Lastly, can I rebuild this thing? It seems ridiculously priced for a dang solenoid. It's a Norgen 4088571, KW part 1802315 superseded to 1949524.

 

So I decided to take apart the actuator and I hope I am providing some extremely valuable info to others with this issue...we'll see if my fix works.

So here are all of the bits and bobs separated except for the valve. I don't wanna break it and I don't believe it needs to be removed.


This is the valve at the bottom of the assembly. My observations and presumptions on how it functions:
-pin in middle pushes down and spring forces it back up
-exhaust port is at the top on the side in this picture(can poke a pick into it)
-when solenoid pushes the pin down the valve is open
-when solenoid releases air flow from inlet is cut off
-when off the seal from the pin to the solenoid is loose enough that the pressure vents out the exhaust


Here's the exhaust port with everything removed. That hole at the top is where I saw my pick from the top of the valve.


This is the bottom of the solenoid. The plastic cap on the right sits on the pin in the middle and makes the seal with the valve pin. It is hard plastic but it has a rubber top. I believe this seal is worn. It shouldn't take much so I'm going to glue on a very thin disc of rubber, maybe 0.5mm.



If this does the trick then that's about a $900 part that fails because of a 10 cent seal...and they don't sell a rebuild kit.

 

I haven't, that's a good call, thank you. I'll check them when I go back to work on it. The way the valve is designed though, I don't think it would exhaust if the butterfly wasn't moving. It seems that when it's open and applying air to the butterfly cylinder, the exhaust should be closed. Although maybe the higher pressure from that would make it leak.

 

Gotcha. Yeah this one is leaking with the key off. Have you ever tried fixing that seal on the plastic cap that actuates the valve?