Overheating

either can be correct. are you sure that the fan is rotating the correct direction for it's design? are you sure your temp gauge is reading correctly? make sure your fan belt isn't slipping.

Capnhowdy is right - when I brought my td15 home we found some one had "converted" it to a pusher fan.

In other words they put the fan on backwards so it was really pushing or pulling air.

Did you test the thermostat? I heat them in a pot of water on the stove and make sure they are opening at the correct temp using a meat thermometer if my IR thermometer isn't handy. Can you see the water circulating in the top of the radiator?

Jordan

A company I worked for in the 80s, supplied me with a GMC 2500 diesel van. The old 6.2. Being I ran a lot of miles each year, I took it in yearly for complete fluid change.

Radiator, transmission, differential, engine oil, etc. After the first time, I had a heating problem in the summer when traversing mountain roads.

I checked out the coolant concentration, and found it very rich. After draining out about 1/3 of the coolant, and adding fresh distilled water, the heat problem went away.

Ethelyne Glycol, does not transfer heat as well as good ol water. If your mix covers way below your local freezing temp., change your ratio.

8u144.
While this may or may not be your problem with this tractor.
Simply reversing a fan on the hub does not change a fan from a sucker to a pusher or vice versa.
If this is done or a fan is mistakenly bolted on the wrong way it will simply result in less air flow.
Some newer machines are equipped with fan blades that can be turned . That is each individual blade can be rotated 180 deg. changing the air flow. Tractors of your tractors era were often available with fixed fans . either suckers or pullers and must be mounted correctly. If you study the fan carefully you should be able to work it out.
A.K.

Purging the air from the petcock between pony and diesel engine would primarily affect the pony cooling.

One thing that might help is to look under the radiator and see if you can block the space where hot air can recirculate. Depends on if you have front mounted CCU or hydraulic unit how easy it will be. A piece of heavy cardboard will do for a trial run.

The other possibility not mentioned yet would be if you have a compression leak into the cooling system.

The fan blades will have a curve. If someone has installed the blade backwards, the "hump" of the blade will be toward the direction the air is moving. Correct installation has the cup side of the blades toward the direction the air is moving.