My 250K mile '99 F250 managed to overheat, lose all coolant (maybe this came first) and run on (over a min after shutdown) without throwing an engine code. The coolant leak seems to have been the water pump. After getting it towed home I checked the oil level and it was over a gallon high but NO coolant (has to be fuel dilution). I drained it and without pulling filter got about 5 gallons. It still turns over but will not fire at all so I pulled the valve covers.

When I pulled the glow plugs, cyl #5 was badly burned (see pic). Cold cranking cylinder pressures were (in numerical order) 350, 400, 330, 350, ZERO, 340, 350, 320 psi. So, number five either holed a piston or burned a valve. This is my first diesel and I don't know which is more likely.

Two questions: first, can cylinder #5 be "deactivated" and still run this truck for a while for local stuff, and two, as a experienced gasoline engine mechanic (hobby) should I consider rebuilding myself or purchasing a long block and just R&R. I have seen good rebuild kits which include all gaskets, seals, bearings, pistons and rings for about $1K (CPP diesel) maybe another $1K for outsourced machining. The best rebuilt long block I have found is about $3700 without returning old core (United Engine). As far as disabling/deactivating that single cylinder for now, it would be ideal to deactivate glow plug AND injector, it already has no compression . I know that diesels rely somewhat on fuel for cylinder lubrication but that cylinder is likely trash anyway.

 

Do not try to "DEACTIVATE" a cylinder on these engines. It'll create additional issues and potentially cause more damage. Also if you dumped a gallon of fuel into the oil and it's ran at all with that then you've damaged bearings in the engine.

Long block it. If it got that hot, there's a lot of potential damage to the heads and block itself including cracks, warped surfaces, scored cylinders, debris damage from failed parts. I've seen a lot of guys keep throwing money at an engine because they thought they had covered it when they rebuilt it but things kept coming back up.

I worked at the Auto Hobby Shop while in the Navy and we had one guy who overheated his engine and blew the head gasket. Found the block was no longer true, head warped, cracked head, after machining everything not enough clearance between the pistons and valves. After the third time pulling the head off his engine and trying to fix it like that he ended up buying a fresh rebuilt and that cured the issues.

 

If you decide on long block go to j&k engines in Texas great stuff there man