Nothing is hot; not the thermostat housing or any of the hoses on either side of the thermostat or radiator. And nothing appears to be moving in or out of the expansion tank. I poured some distilled water into it, and that's all that's in it now after the engine ran for ten minutes or so. No coolant came up into the tank, and the water was never pulled down into the system.

 

So is the system not full of coolant?

 

Fine, you win this round, Extinct. I added water and coolant, and now I have flow again. The coolant level was right at the cold indicator, so I guess that doesn't actually mean much. But the truck is still trying to overheat. I took the thermostat out and tested it on my stove. It opened at 190 like it's supposed to. I tried running it without the thermostat, and it came up to temperature in about the normal time, then kept on heating up until I shut it off to avoid overheating. Revving didn't do anything. So I seem to be back where I started. I did notice that I have several minute cracks in the expansion tank, so I'm going to replace that, but I don't know what my next diagnosis steps should be.

 

Could You post the corrrect bleeding method with the inline?
I also have the waterfall sound from the heater matrix and it wont blow HOT air in.
Do get warm, but a lot colder than my TD5 blows.

EDIT:
I did this too, with the expansion tank lifted up, and the front of my D2 on ramps ~a foot higher than rear.
I might have revved too much as there was coolant coming out of the expansion tank. Gladly I had the cap on, but very loosely.
Did not help.

 

@mendenhall2 If am clear you have movement in the tank but still overheat significantly. You have 1 of 6 possibilities :

• Insufficient coolant
• Fan clutch is shot
• Clogged rad
• Dead or dying water pump
• Head gasket failure
• Worse case cracked block

Start with number 1 & 2, leave the thermostat out it makes things easier.

• Remove the expansion tank from it's bracket and lift it as high as you can.
• Top it up to the cold fill line and then start your engine - cap off
• The coolant level should drop should if you are low
• Top up until the level stays at the cold line.

Fan Clutch testing

• With the engine off, spin the fan by hand. Some resistance indicates the clutch is working. If the fan spins freely with no resistance, the clutch is bad.
• Wobble the fan. If it wobbles, the bearing is bad and the clutch needs to be replaced.
• If the fan has heavy resistance or is frozen and will not turn, it is also bad.
• Visually look for signs of silicone radiating from the center of the clutch, indicating a failure.
• Start the engine and observe the fan speed. If the fan freewheels when cold and do not pick up speed as the engine temperature rises to normal, the clutch has failed.
• If in doubt replace the fan clutch.Tools Needed

The next 2 require some disassembly to check at the very least dumping you coolant, then you can use a borescope to check the water pump & rad

• Drain the coolant and remove the serpentine belt
• Remove the hose into the water pump
• Insert the borescope and check the impeller blades
• Then spin the pump by hand watch the blades - the pump should spin freely with no wobble and all the blades should be intact
• Try and move the fan clutch forward and back and up and down movement could be a bad bearing
• Check the bleed hole for signs of moisture - it is at the bottom passenger side of the pump

The rad is a pain there is no good way to check for partial blocks but.

Try the borescope and see if you can see any signs of crud build up, if not flush the rad from the bottom to the top - hose in the bottom up the top hose to direct the water into a bucket if possible to check for debris. Then flush the other way.

Last simple thing is to drain some of your oil and check for water, but you need to catch the oil and watch for the water. A couple of liters should be enough as any water will be at the lowest point.

 

Fantastic, thanks for the diagnostic guide. I'll report on my findings.

 

All good steps, but the diagnosis is actually much easier. First we need to validate that the truck is actually overheating. Now that we have it full of coolant and the thermostat out of the housing it gets pretty simple. We need to determine if it is actually hot or if the sensor is just saying it is hot when it is not. The best way to do this is with an IR temperature pen or laser gun like this:
Measure the outlet pipe of the intake manifold and/or the thermostat housing, the drivers side of the radiator, the passenger side of the radiator, and the lower radiator hose near the inline splice. Do the testing with the cap one full turn loose from full tight so that it vents and does not build pressure during the test.

How long does it take to go from stone cold to overheating with no thermostat installed? I assume it is getting how sitting still in the driveway? How is the airflow behind the engine fan? Should be about 15 to 18 mph windspeed typically, you should be able to get a sense without instruments based on how hard the wind is blowing.

Assuming it is actually hot, then it is either a plugged radiator (you can tell by a significant temperature difference between PS and DS) or a bad engine fan (equal temps side to side on radiator but no airflow across rad). Blown HG and not even cracked block can overheat with a good radiator, good cooling fan, and no thermostat installed.

 

Ok, I was able to verify that my fan seems to be OK. It does not wobble or spin freely, and appears to create a healthy airflow across the radiator. I picked the expansion tank up as far as I could and broke off the plastic line coming from the throttle body heater. I live in Florida, so I did an impromptu bypass. I poured in ~1 quart of distilled water until the glugging stopped, and started the truck with no thermostat. It was fine for 11 minutes until the temperature jumped from ~190 to 220 and I shut the engine off. I had the cap on less a full turn, as suggested. My Kobalt infrared thermometer only showed 106F at the thermostat housing, but a decent quantity of water was expelled from the overflow hose at the expansion tank, so I don't believe that number. I couldn't get good readings at the radiator, either, unfortunately. When I saw 220 on the scangauge, I immediately tried to rev the engine to see if the temp would come down, but it didn't move.

About 30 minutes after shutting the truck off, I thought to check the oil. I opened the fill cap, and saw this:



Panicking, I drained a bit of oil from the pan, and saw this:


That actually wasn't as bad as I thought it was going to be. So do I have a small leak in my head gasket? Do I need to borrow a boroscope and start pulling sparkplugs? Or am I still chasing a waterpump? I don't believe the head gasket has ever been replaced, so I won't be surprised to learn that it's bad after 145k miles, but I don't want to jump to such an involved repair if something else is actually going on.

 

I borrowed a compression gauge from a local car parts store, and completed a compression test on the left bank before it got dark. Cylinders 1 and 3 both showed 150 on the nose. Cylinder 5 only got up to 115, and #7 got up to 130. So I don't think that looks very promising.

 

115 is a little low. Cap does not look great. I would trust the IR, did you feel the hoses with you hand? I suspect you have the beginning of a blown hg, some exhaust gas is getting in the coolant and causing a spike in the temp sensor reading but the engine is not actually hot. The engine, oil, coolant and all the components have a lot of thermal mass and the temperature cannot change suddenly but the sensor reading can change suddenly if there is a vapor pocket. Vapor pockets don't damage the engine, getting the entire assembly way up over 230 does. Suggest you rent/borrow the cooling system pressure tester from Advance and warm the engine up, then subject it to a pressure test and see if it can hold pressure. If it does not, you either have a leak or a blown hg.