My ancient Deere 2040 cannot be run but about 30-45 minutes in the summer before it overheats, making it pretty useless. When the ambient is less than 80 or so, you can run it for maybe 90 min before it gets too hot. This isn't exactly a new problem but, it does seem to be getting worse.

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I've had the radiator out and checked (OK), the water pump out (OK), checked/changed the thermostat (OK), looked at the water flow into the top tank (seems OK) and I'm now running it without the thermostat (no change).

I'm beginning to think that maybe it isn't the cooling system that is the problem.

FWIW, it has a closed center hydraulic system and simply running the tractor without using any hydraulics (power steering and a loader are the only hydraulic appliances that it has) will eventually get the steering column and loader joystick body too damned hot to touch.

I'm thinking that for some reason, the hydraulic pump isn't destroking completely when it's not in use because of a leak/bypass somewhere in the system and the thing is pumping a little all the time, something IIUC, a closed center system isn't made to do thus heating the hydraulic fluid in the tranny housing and that, in turn, transfers heat via conduction to the cooling system.

Also, since I've owned it, the loader has always crept upwards (very slowly, almost imperceptibly) when you run the tractor.

Any advice?

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