crank case pressure

[Waterloo]

If the coolant in your bottle is rising, it is more than likely the head or gasket with the miles on your truck. Are there any sever overheats in the ECM history, a good thing to check. Me, I would go to NAPA, or other auto parts store and purchase a block test kit. It only takes a matter of minutes to do, and will tell you if you have exhaust gas leaking in to your coolant system. I bought mine at NAPA, it diagnosed my bad head in a matter of seconds, literally. https://www.napaonline.com/napa/en/p/BK_7001006/

One other thing you can check is your air compressor, sometimes they clog with soot and divert air back into the system. I'm having a brain fart, and cannot remember the line you remove and plug to test, one of the guys will chime in on how to do that, or do a search here on the site. Or, you can drain the air out of the tanks, leave the tanks open and start the truck. If the pressure build up in your coolant system stops, check the air compressor. That is a simple test to do... But I'm thinking head or possibly a dropped liner from what you are describing.

A little History, I bought my ProStar with 690,000 miles on her. Looking back, it had a bad head or gasket when I bought her. The DPF EGR issues I was having masked this problem, and I was totally uneducated on these systems. The DPF eventually cracked at 780,000 miles and I did the mandate removal. I did not have $7000 for a new DPF/DOC can and associated parts and pieces.

I drove mine like that for nearly a year, with the bad head and mandate removed, but that head had it's consequences. I was blowing coolant lines, blew my radiator apart (thankfully while parked at a customer and not driving) and lots and lots of coolant, hoses and downtime to make repairs. When it finally gave up the ghost, I had coolant shooting a few feet in the air out of my open coolant bottle... That was at the same time it took out my Tri-Pac lines and left me stranded on the side of the road... It was time. If you are to the point your coolant is rising in the bottle in a matter of seconds, you do not have much time left IF it is the head or gasket.

If it is the head, go new, not reman, they are having issues with Cummins reman heads according to a few of the mechanics on here that do this kind of work. They are roughly $400 to $600 more than a Cummins reman, spend the extra money and do it right with a Cummins factory OEM new head. It is also a good time to be rid of the mandate, but that is just my opinion. I feel for you, this is not fun, not fun at all.

I hope this is something simple like a sooted up compressor line, fingers crossed, praying for you and throwing chicken bones!