Over the past month, I've replaced the injector cups (thanks Riffraff), R&R'ed the oil cooler, Guzzle flush, and reman injectors (AB stock, thank you Full Force Diesel). The truck had been taken apart about a month ago, and everything drained dry. Then life got in the way and couldn't get back to her until last weekend.

Old cups came out easy, the holes cleaned up easy, and the new ones went in easy. Allowed to cure for several days. Prefilled the HPOP reservoir, and tried to draw out as much air from the HPOP lines as possible, using a vacuum on the front port on the pass side, and supplying oil on the drivers side. An HPx was previously installed (and not touched this time).

The first part of the rad flush was done a month ago, and the distilled water part was done after re-assembly today. Even with my HPOP bleed attempt, it still took quite awhile to build up ICP for a start. I have the FRx also from last summer. Running it w/o the thermostat sprayed plenty of water out from the gasket-less thermostat housing, which I hope means a good water pump (original, to the best of my knowledge). I then installed the thermostat, and added the coolant and SCA, but I do not see any flow through the degas bottle and the upper rad hose stays cold. And I've driven it plenty enough locally to get it to heat up up. Heater hoses are plenty hot. The temp gauge levels out right where it always did. I changed the new T-stat for another new T-stat, same thing. Even checked the T-stat for clearance while installed by gently pushing it open with a long punch through the outlet housing.

And yes, the obvious answer is to check the thermostat, which I will do when I get home (boil it test). After changing the T-stat, I had a long crank to get good ICP, hoping this is still air and unrelated, maybe 30-45 minutes runtime, and a 1/2 mile jaunt around the block twice. And aside from this, the engine runs great.

I'm lost, any ideas??

 

It takes a lot longer than most people realize for these engines to come up to operating temperature. Then when the thermostat does open, it may close again pretty quickly as the cold coolant is drawn in from the radiator. After testing the thermostat, take it out on a 15-20 mile drive and see if the upper hose is warm when you get back.

 

Per the temp gauge, it's at operating temperature, and it's heading to 80 F around here today. My "proof" per Guzzle, is the flush. I drained it, using the engine plugs, and only added the 4 gals of antifreeze, SCA, and a half gallon of water. The level is right at the top of the degas cap, and it hasn't moved a bit, with two drives now. This time I went a little further, and just exchanged the first T-stat for another.

 

My gauge appears normal by the time Torque tells me my oil temp is only about 150.

 

Well, the third T-stat seems to flow much better, as a quick trip around the block had the degas bottle almost empty by the time I got back. I will boil the other sometime to see if it opens.

Now that I know she won't overheat, I can take her to the highway and see about air in the HPOP lines... Still a long crank only 20-30 minutes after a run. Torque shows the ICP near zero when I hit the starter.