You’ve been working all day in the field setting up your seeding equipment.
You are running in and out of the tractor and haven’t been watching the gauges carefully.
Now it is late in the afternoon and you want to make time. You are ready to start planting so you jump in the tractor and crack open the throttle.
You have made a couple of rounds when you glance at the gauges and see the coolant temperature light is on.
Your first thought is, “how long has that has been on,” and the second thought is, “why is it on?”
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You take a look and find no leaks. You wait till it cools a little and find that the water level is not low.
Now what?
There are several simple things to check:
- Is the radiator plugged with dirt?
That seems too simple, but you could have been using the tractor in an oilseed field last fall.
If at that time you had to wash out the air filter, you probably should have washed out the radiator as well.
It can get a coating of oil that the dust will stick to and not allow heat from the coolant to dissipate.
If this is the problem, you will usually also have air conditioning trouble, but if it’s cool like this year, you may not have turned the air on yet.
- The fan shroud could be distorted or have a chunk missing so the fan is too far away from the shroud.
If that happens, air will be drawn in without going through the rad. The shroud should be as close as possible to the fan without touching.
This will force air to pass through the radiator unless it is fully plugged.
- The thermo coupler on the fan hub should be working so the fan is pulling air rather than idling free on the shaft. You can feel the blast of air.
- The radiator cap might have failed. It should be tested to see how much pressure it holds.
Water boils at 100 C at sea level, but the boiling point is higher when under more pressure. That’s why you can run your engine at a temperature higher than 100 without boiling the coolant.
However, when the cap fails, the boiling point falls into the operating range of the engine.
- The thermostat could be stuck in the closed position. If this is the type of system that uses a plate on the thermostat to block the bypass, that means the bypass would be open and the coolant would just circulate in the block.
In this case, the engine would be hot but the radiator would be relatively cool.
Make sure you get the right thermostat, and don’t think you can run an engine without a thermostat. It won’t be long until you don’t have an engine to worry about.
There are also things that aren’t so simple to check:
- The water pump blades could be worn out. You should have changed the antifreeze every two years like the book says because the water pump lubricant only lasts two years.
After that, the water pump will begin to wear out rapidly.
- The radiator cores could be plugged from the inside. This could be dirt or solder that has let go from a previous repair job on the radiator.
I have seen cores plugged from what looked like too much radiator sealant.
You need a certain amount of flow for any given horsepower, which is why you need bigger radiators when you put a bigger engine in the same size tractor. You can’t really measure the flow accurately unless you have the proper equipment.
- There might be too much air in the coolant, which shows up as bubbles or foam in the hose that connects the engine and rad.
Every wet sleeved diesel engine produces bubbles by the explosion in the cylinder. This vibration causes bubbles to form on the outside of the sleeve. The bubbles change the coolant around the sleeve into an insulator.
Manufacturers get rid of the bubbles by circulating coolant from different parts of the block and by putting baffles in the radiator.
You could go to the trouble of installing a clear plastic tube in the bottom radiator hose to look for the problem, or you could just put in a surge tank. A tank solves the problem.
What kind of damage can you have if the engine has been getting too hot too long?
- Injectors start hanging up, which will show up as discoloured pintles or scoring on the pintles. The engine starts smoking and losing horsepower.
- Cylinder walls start glazing, which shows up as coloured shiny spots on the cylinder walls. The engine starts using oil.
Don’t worry about damage as long as your engine still has horsepower and isn’t using more oil. However, ensure you have done what you can to avoid future over heating.
Henry Guenter is a retired Massey Ferguson service manager.
