The plugs all look great. I went for a drive to warm the engine and did a leak down test but not a compression test. All of the cylinders showed between 17 and 24%. All were leaking into the crankcase, since they were similar I am assuming that's from the rings gapped for boost. No sound from exhaust or throttle, just the vent hose. And none were pressurizing the cooling system. I checked that by removing the 1/2" hose from the coolant reservoir and plugging it. I left the pressure cap on so that any pressure should come out of the hose nipple. I went through it again pressurizing each cylinder without the tester. I wanted to get as much pressure as possible even though my compressor tops out at 115 psi.
Would a compression test tell me anything? I did the leak down first simply because my compression tester leaks. If not, what's next?

 

If your leak down and every thing else looks good your probaly fine.

The video Is not very good and nothing can be detrmined from it alone. I see moisture coming from the truck it self like it was rainging out side. I suspect the humidity and the truck being a first cold start in a while that it's likely just condensation your seeing in the exhaust.

If the trucks warms up to full operating tempature and the cooling system isnt pressurized and your not loosing coolant, than there is nothing wrong.

Condensation in the exhaust on a cold start up is normal esspecially when it's cold out and there is high humidity.

 

Even in winter, it over heats if I drive more than about ten minutes, sooner if I press the throttle hard.

 

Maybe the waterpump or thermostat is having a problem? Or you are definitely losing coolant when it's running?

 

Even after it was fully warmed up in the winter, I could see steam coming from my exhaust leaving a stop. It seemed like a lot more than the other cars on the road, and at idle in the parking lot, there was more than in my video above. I was never positive that it smelled like antifreeze, I stuck my nose in the steam several times. But it was the steam that sent me down the road of assumption that it is an internal leak. And yes, if I drive long enough with the gauge showing elevated temperatures, it will lose a lot of coolant. I am not sure that it wasn't coming from the overflow.

Let's say it is the thermostat or pump. I don't understand how a thermostat would allow the engine to maintain the normal temperature for a certain amount of time and then gradually start overheating. Is that possible? Or, could the impeller come off my relatively new, less than two years old, water pump? Is that a thing that actually happens?

I guess if my truck didn't keep thinking of ways to break that I have to use my brain (and your guys brains), it would feel neglected.

 

I am thinking about trying again with a compressor that will bring it up to 175-200 psi. Any thoughts?

 

Need to block test it. Possibly warped the gasket or head. That cause some coolant into the cylinders when up to temp or on cold start up.

 

That would also cause it to overheat while running. If exhaust gases get into the coolant, that'll make it crud up like milk under the coolant cap and heat up the coolant while driving. Would always replace thermostat when it gets past 3/4 temp. Its easy and simple and can clear a lot of head aches

 

Okay, I will try a thermostat first. What does block test it mean?

 

Test kit -> https://www.napaonline.com/en/p/BK_7001006

Richard