I purchased a 2004 F350 with a 6.0L in June to haul LTL hotshot loads with. I leased the truck to a driver. On the trucks first trip it broke down in Idaho and had a $5,000 bill(independent mechanic); Oil coolers, EGR air to air and Turbo heads were ok, I assume new head gaskets. About a month later the driver came to pick me up to run into the cities with my car on the back, he was going to haul other items on his trailer. The morning he came over the truck was pouring white smoke, he said was a dirty injector. We got into the cities and there was a plume of black smoke we pulled over and there was oil all over the hood, engine compartment. He made me drive the truck, we continued onto my mechanic (to drop my car) after checking oil level which was full. Dropped the trailer and drove home, got about 10 miles away and the truck shut off. We didnt try to start it again that night. I started the truck about a week later, I did not hear any knocking or abnormal noises.

Truck was towed back to my place. It was suggested by a family friend that I have it diagnosed by a Ford Dealership, if the repairs a month earlier were faulty possibly a claim on their garage shop insurance.

The driver attempted to drive the truck into the Ford Dealer and the truck shut off again about a mile from my home. I had it towed into the Ford Dealer and they ran a diagnostic. Cyl 3&4 misfire and contribution codes pwr balance. Found number 3 missing relative comp test 3&4 low. Ford wants to run manual comp test and pull injector #3. They suspect broken injector or blower cylinder.

I had the truck towed home, and it is a lawn ornament.

Question being why would I want to spend upwards of $400 to find out if I have a blown engine? Could it be the high pressure oil pump? Something else? Or do I start planning to build Fummins?

Thanks in advance