I did the checks like armygreywolf advised. Oil at drain is clean. Radiator is empty/oily.

I then decided to let a shop take over. I had them diagnose it. Came back as bad fuel pump and faulty/bad FICM. He wants $2,500 to 3k for the FICM. With total being around $5,000. I declined. Going to do some more research on what’s involved. I see on the diesel forums a few shops that repair them for $200 to $500.

I asked if he thought cooler was blown. He didn't investigate any further after finding the FICM issue. I am fairly confident this shop actually knows what it is talking about, but I can't afford to have them repair it.

I am confused on why it started at one point and now it won’t.

Oh well. Gives me something to tinker on.