Cat c15 Sdp air locking

I forgot about this..... the shop who did the water pump had found this in the old water pump cavity.

 

So this pipe here.... I brought it to the mechanics to get put back in place. I filled my coolant resevoir and bled it out, started driving it there with the rad cap off and while I was driving.... I lost heat in the cab again just like always, I had to stop and rev it up to 1900rpm to get it to circulate enough that I got heat in the cab again. Seems to air lock the cab heater section even with the rad cap off!

The mechanic put me o rings and even a sealant in to hold the pipe back in place, ran it for 45 minutes without the cap and it was fine.... but 15 minutes running with the rad cap on and the system pressured up enough that it blew the pipe shown above out again!

Once again...... No combustion gases present in the coolant. I've isolated the compressor and no change. Just curious if anyone might have any other suggestions before we decide it's a motor teardown.... it seems odd that it would pressure that much without combustion gases present.

Side note. I've noticed in the past that there is 2 venting tubes on my pererbilt. 1 that vents from the thermostat housing to the front of the expansion tank which is always hot as coolant is constantly flowing through it.... and a little vent hose that runs directly from the top of the radiator to the back of my expansion tank. I've noticed this one never gets warm. Asked the mechanic but he doesn't seem to think that being plugged could cause this much of a problem this quickly, even if it were plugged.... gonna check it out anyways.

 

No more cgi, no more pre cooler, oil cooler switched to old style.

Both test kits were brand new.

 

No, it's there so I didn't have to build a custom intake pipe but it's capped off.