1994 6x4 gas FD620D overheating, why - John Deere Gator Forums
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post #1 of 4 Old 12-07-2019, 11:18 PM Thread Starter
Rlclayton6X4's Avatar
Join Date: Aug 2019
Posts: 47
1994 6x4 gas FD620D overheating, why

My 94 gas 6X4 has started overheating. I replaced the muffler and decided to check the water pump while the exhaust was off. I removed the cover and all inside looks new and very clean. Impeller looked new, vanes on impeller perfect And the pin is in place on the impeller. You spin the engine over and impeller rotates. Cleaned cover and pump surfaces put on a new gasket on a closed it up. Topped off radiator and all seemed fine. Ever since the temp light comes on after about 15 mins. After cooling off I removed the radiator cap and it’s full. Ran with radiator cap off and it’s moving coolant. Put cap back on and it did it again. Changed thermostat, no help. Found bleeder plug, bled it and fluid moving with cap off. Put cap on, ran 15 mins, hot again ! Took thermostat out, same thing. Removed new exhaust and checked pump again. All seems well. Bled again, same deal..15 mins and hot again.Elec fan comes on but engine doesn’t cool off. Frustrated !! Any ideas??
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post #2 of 4 Old 12-07-2019, 11:56 PM
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טים ירושלמי's Avatar
Join Date: Sep 2018
Posts: 426
If everything else is working as it should than its either a clogged radiator or engine.
Maybe flush the system..

I know these can be really bitchy about trapped air aswell so make sure all the air is out, squeeze the pipes a little and maybe raise the filler neck a bit.

Last edited by טים ירושלמי; 12-07-2019 at 11:58 PM.
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post #3 of 4 Old 12-08-2019, 07:44 PM
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Location: Door County, WI
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You've done everything I would have to diagnose/solve the problem. The fact that the fan comes on says you're circulating coolant from the engine since the fan sensor is in the radiator. This leads me to think you have a clogged radiator. Pull the bottom hose and see how fast it drains.
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post #4 of 4 Old 12-08-2019, 10:41 PM Thread Starter
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Posts: 47
I pulled the radiator out and cleaned it inside and out. It had some dirt in the lower 1/4th of the radiator fins. I got this gator back in early April this year and other than check the coolant level I hadn’t really done anything but put a new sensor on the engine and made sure the idiot light worked. All the hoses were original and had a date stamp of July 11, 1994 ! They looked fair but I went and bought 10’ of 1” Id heater hose and replaced them. Put radiator back in with new hoses, filled it, cranked it with cap of. I bled it and added coolant to the right level and put the cap on and it ran over 39 mins and did not overheat ! I didn’t get to run it yet under load. Will put cover and seats back in tomorrow pm and try it
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