I really hope someone can help me and point me in the right direction:

I recently acquired a 1972 Cat D4D dozer, which I believe has a power shift. I was told that it had sat for 4 years in the field. Unfortunately, once I started working with it, it began to overheat severely. I'm not referring to any strenuous activity; this happens simply when driving in, for example, second or any other gear.

Now, the strange thing is that at idle or high idle, I can let it run for an hour or longer. It does slowly climb above the thermostat opening temperature (taking 45-60 minutes), and then the temperature basically stabilizes there. I didn't manage to overheat it when just high idling. I let it run for almost 2 hours with no issues.

However, once I drive it, it takes less than 10 minutes before it reaches the red zone on the temperature gauge. After a cold start, I may get about 20-30 minutes or so.

I checked the thermometer; it seems accurate. The red zone starts at around 210°F-215°F.

I also measured the entire system from top to bottom. Here are the readings from the infrared thermometer at operating temperature (regulator/thermostat open):
- Thermostat housing: 180°F
- Radiator inlet: 178°F
- Radiator outlet: 143°F
—> The radiator seems to be fine.
- Pump top/outlet: 180°F
- Pump bottom: 142°F
- Oil cooler in: 180°F
- Oil cooler out: 193°F
- Transmission oil in (not driven): 184°F
- Transmission oil out: 195°F

I also measured the pump pressure:
- Pump pressure cold: around 15psi
- Pump pressure warm (Thermostat open): less than 10psi

Unfortunately, I only had a pressure gauge from a compression tester. It's hard to tell if it's 9psi or 5psi when warm (180°F), but the pressure drops significantly compared to when the thermostat is closed.

The thermostat is new.
A block test was negative (blue).
There are no bubbles in the radiator once warm
There is no oil in the coolant and no water in the oil.
No external coolant leaks. 

Does anyone have an idea of what I could look for next or what could be causing this?

Your heating problem is being caused by the transmission and torque converter overheating. Check the simplest things first. Are the brakes unlocked? Have you checked the transmission oil level? Let us know what you find.
Craig

Thank you for your quick response.
The oil level is slightly above the max on the dip stick. The oil itself is milky. Like very milky. Most likely from sitting all those years in the field, exposed to the weather.

The brakes are sticky but do work. The pedals don’t return on it’s own at moment. Work in progress but I don’t believe they are locked.

But how could the breaks cause the coolant to overheat? Isn’t it a dry clutch?

Please post your serial number, 1972 D4D has very little meaning.
Bob

The serial number is: 83J1810

Your machine is a early power shift and the brakes are dry. Or at least it came that way.
Does the temp gauge on the torque converter work?
your readings on the transmission oil cooler might be backwards.
If the gauge on the torque works put the transmission in 3rd gear, stand on the brakes and run high throttle and watch the heat gauges.
Bob

bluox wrote:

Your machine is a early power shift and the brakes are dry. Or at least it came that way.
Does the temp gauge on the torque converter work?
your readings on the transmission oil cooler might be backwards.
If the gauge on the torque works put the transmission in 3rd gear, stand on the brakes and run high throttle and watch the heat gauges.
Bob
 

You are right, my readings for the transmission oil cooler is backwards 

I‘m not sure if the transmission oil gauge works, the needle does move a bit but the engine is just way to fast overheating to really test the other instruments.

Is the possible that the impeller of the water pump is loose or worn in a way that it can’t pump enough coolant to cool the engine?

Very milky oil usually indicates the transmission oil cooler has failed or water has entered from another source. If the the tractor was run a long time in this condition you might have serious transmission problems. 
The torque converter uses the engine coolant to keep it's temperature down via the trans. oil cooler. bluox is correct you can test the gauge by standing on the brakes with the tractor in 3rd gear and the engine at full throttle. The gauge should rapidly rise toward the red. 
Craig

seiscat wrote:

Very milky oil usually indicates the transmission oil cooler has failed or water has entered from another source. If the the tractor was run a long time in this condition you might have serious transmission problems. 
The torque converter uses the engine coolant to keep it's temperature down via the trans. oil cooler. bluox is correct you can test the gauge by standing on the brakes with the tractor in 3rd gear and the engine at full throttle. The gauge should rapidly rise toward the red. 
Craig

Sounds like that I have to replace the transmission fluid rather sooner than later… I will take care of it today.
Could the milky trans fluid cause the coolant to overheat?

I just tried to stand on the brakes in 3rd gear. The gauge doesn’t rise at all. So looks like it’s not working.

This new gauge is available on eBay:
www.ebay.com/itm/383670453640