Ask the Mechanic

Steve Thompson, Contributing Columnist

READER: I have a John Deere 5083 that started getting hot for no real reason. The reservoir is half-full, and there are no visible leaks. It will not heat just resting there running, but when I head down the road, it goes over to red on the heat gauge. I changed the thermostat because I thought it was sticking. Nothing changed. I changed out the temperature sending unit. Nothing changed. I blew out (two times) the radiator and all those other coolers in front of it. I washed out the radiator and other coolers. I thought it may not be getting hot, so I finally borrowed an infrared meter from a friend, and the tractor's gauge is correct. The meter showed 220 around the thermostat area. What do you think is the problem?

STEVE: More than likely the problem is the water pump. This tractor comes equipped with a water pump that has a plastic impeller that can become loose on the water pump drive shaft (see photo accompanying this article). Don't be fooled when you inspect it after you remove the water pump; it looks like everything is OK. However, when you turn the input shaft and hold the plastic impeller, I bet you will see that the shaft is just spinning in the impeller.

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-- Email Steve Thompson care of askthemechaniccolumn@gmail.com, and be sure to include your contact information and phone number.

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