JD 4320 Engine Heat Question

I have a 1972 JD 4320 that was my Dad's that has 4800+ hours on a working tach. When we had the farm sale for my Dad in 2006, my Uncle bought the tractor, but really didn't use it at all. Probably 200 hours in 11 years. I finally got it bought early last year.

The trouble I am having is it seems to be heating up. When I first started it, after it sitting for about 6 years and not being ran, was that the waterpump was stuck. So I took the hood off and replaced the WP. I also ended up replacing the radiator with a new A&I radiator, new belts, hoses, and thermostat. Since I had gone to that much trouble, I also replaced the water temp gauge with a new JD gauge.

All seemed well. This summer I put it on a V rake. Just driving down the highway about 4 miles to a field, it seemed to want to run a little warm, about 1/2 way between straight up and the red. That was just pulling the rake in road gear. In the field it was about the same, maybe a needle width cooler. Drove the tractor home last night at about 95 degree air temp, and it seemed to run warm again. When I got home, I immediately checked the block with a infra red temp gun. The block was about 180F. The lower rad hose was about 140F.

I am must wondering if the new gauge is reading wrong, or if something else might be going on. The timing is set on the money. My guess is the temp gauge, but also wondering if the heat gun on the side of the block would be a good reading? Any thoughts? It is a low houred tractor and has really never had to work in it's life. My Dad bought it when it was 2 years old and really never used it much either. Put up hay for a couple of years and then sold the cattle. Used it for drilling wheat was about all after that. Let me know your thoughts. Before and after pics belwo Thanks - Bob

180 is not hot. I usually run 180 degree thermostats in diesels. Helps keep them from wet stacking in cooler weather. Your radiator is working if your having a forty degree drop in temperature. Especially with 95 degree ambient temperatures.

The darn gauges that are not labeled with actual temperatures really do not tell you anything, unless they boil over at the red line. I have two JD 4020s that the gauge runs right at the red line, when they are working. Checked them with an accurate gauge and they are running right where they should be, 180 degrees.

It is about ready to melt down! I should take it off your hands.

Check the temp of the top back of the head, where the heat gauge "bulb" is inserted, then you'll know for sure if the gauge is "off" block temp will be at least a few degrees cooler than where the heat sensor is.

Thanks a lot for the replies. I can't believe it is actually overheating, but just wanted to make sure that my heat gun was telling me the truth as well. I'll check the temp at the top of the head where the sending unit screws in.

I did change the thermostats. I am thinking there were two of them, but maybe just one. This was last year. They were JD thermostats, however, and what the parts books called out for.

I hate to think a new JD gauge would not read correct, especially as much as they cost, but it could certainly be. Thanks again - Bob

Did you vent the air out of it as you filled the coolant? I leave the sender bulb loose till I get coolant. Seen several overheat when new coolant was added and not bled.

4020 here has always run straight up halfway on the temp gauge since new. It got warmer once when there was a pinhole in the radiator. Seems fine to me.

If its getting too hot coolant will be low,expand run out overflow. My 40110 always ran with needle in middle

Nice looking tractor!

The coolant should be 195F when leaving the top of the engine and on it s way to the radiator .
The tractor is not operating hot . As previously stated the factory guess-a-gauge can cause unneeded worry .