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JD 620 running hot

T

TWS

New User
My JD 620 has started running hot. I can bush hog for about 30 minutes before the temp reaches 200 degrees and I have to stop. I changed the thermostat, then removed the thermostat, then ran through a couple of bottles of scale remover.....no change. My radiator "looks" fine.
What should I do next?
 
Had you used this tractor to bush hog in hot weather before?? You may just be working the tractor hard enough now to bring it up to temp. If you had used it to bush hog in hot weather before and it ran cooler I would do the following:

I would first check to see if there is any trash in front of the radiator. Brush hogging does tend to stir up trash that is sucked into the radiator. You might take a hose and nozzle and spray from the back side of the radiator and wash out all the dust, dirt and trash. Next, I would check to see that the impeller in the water pump didn't come loose from the shaft. Also check to be sure that the clutch facings on the fan aren't worn enough to allow the fan to spin freely on the shaft.

All that said, 200 degrees isn't all that hot for the older JD's. In fact, it was necessary to run them that hot or hotter for proper combustion of the power fuel. Don't know if it is too hot for the newer 20 series tractors or not.
 
One thing to check would be the timing advance mechanism in the distributor. If it is frozen and not advancing the running timing, it could cause the problem.
 
Some people mistakenly believe it's better on an engine to run them cooler (between 160 and 170 or so)... not true. 200 degrees is fine. Better for combustion, fuel economy and oil change intervals. Now if it gets hotter than 225 or 230 I would be looking for issues. By the way I don't trust gauges. Hope that helps. Gerard
 
I had to back flush one of those radiators once.
Had to pull the bottom hose off,top water inlet off and put water hose in bottom and also use air nozzle at the same time. Got alot of junk out. I knew that the rad. core wasn't that old.
 
The A & B without a water pump and NON PRESSURE radiator always run at 212 degrees and the manual says if it is not using water it is not running too hot. NOW ON YOUR TRACTOR IT DOES HAVE A PRESSURE system and water pump so with that pressure system it should be OK at 230*. Remember your cars run about 240* at all times with there pressure systems.
 
Hi, guys. I appreciate all your help. 1. The tractor ran for years at 170 degrees, no matter what I did. 2. the rediator and grill are kept clean and spotless; no debris buildup. 3. the temp doesn't slow down at 200 degrees. It just keeps getting hotter until I stop working it. 4. When I fast-idle it, it takes forever to cool down - over an hour.
 
If the shutters are on the tractor there is a possibility the control may not being working correctly. The control is located at the bottom of the shutters and touches the bottom radiator tank. This small control opens and closes the shutters. If the control is defective the control will close the shutters as if the tractor was just started. It can be checked with hot water, off the tractor. Call me at 864-933-0681 for the test.
Thanks,
Bruce
 
If you pulled the grills and checked behind them and all is clear, and if it has shutters and you made sure that they were open, then I would say that either your radiator is plugged up, your water pump isn't working properly, or your timing is off. Unless you have put in a new rad core in the last year or so, it would be wise to take it in to a rad shop and get it cleaned out. If it is the original core, you might get to replace it after the cleaning, though. Be sure that the belt is tight on the water pump. I've known a couple of tractors that the impeller came loose from the shaft and wasn't circulating the water like it should. It will take some detective work, but there isn't much that could make it run hot. Just check one thing at a time until you come across the culprit. The only other thing I can think of is that if an engine is ran lean, it will run hot. Are you running the tractor on vapor or are you switching to liquid after the engine warms up and under load?? Just making guesses now.
 
Just thought of something. Check your fan blade friction discs. Maybe they are slipping ? You should be able to rotate them, engine shut off,but they should turn hard.
 
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