Are you mechanically inclined? Most farmers know how to fix their equipment, but do you know how to diagnose why things break down? Everyone at the coffee shop will offer you an opinion. But who is right?
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This quiz will help you discover the root issue of some potential farm machinery issues. The correct answer to each of the five scenarios presented appears at the end of the article. No cheating! But if you keep reading, I bet you’ll have the most informed opinion among your farming friends next time you get together.

1. Your liquid-cooled UTV started to run hot, according to the gauge. You checked the water pump drive belt, radiator and coolant level, and all seem fine. You decided to change the thermostat in the hope that it is the problem.

The parts man at the dealership hands you the proper thermostat, and you notice it has stamped on it 180. You ask the counterman what that means, and he tells you it is the temperature rating.

You install the new thermostat, and all is now fine.


The next day at the coffee shop, you ask your farmer friends what the 180 stamped on the thermostat means.

Which farmer is correct?

A: Farmer A says it is a manufacturing code or part number, and it means nothing to the end-user.

B: Farmer B claims it is the liquid temperature in Fahrenheit degrees that the thermostat is fully open.

C: Farmer C tells you it is the crack-open temperature in Fahrenheit degrees when the thermostat begins to open.

D: Farmer D says it is the size of the thermostat in millimeters.

2. You were able to catch a high in the market and sold all of last year’s crop at a firm price. You will take some of that profit and buy a new pick-up truck the farm needs.

You are thinking about getting a diesel-powered one due to the fuel economy over gas. You do not know why diesel engines use less fuel, so you bring it up the next morning at the café.

Which farmer is correct?

A: Farmer A is convinced that because of the turbocharger, the fuel economy of diesel is better than a gas engine.

B: Farmer B tells him that is not correct. He says diesel fuel has more btu of energy than gasoline, and the higher compression ratio is the reason.

C: Farmer C claims that diesel fuel evaporates more slowly and does not lose power to the air.

D: Farmer D tells you it is because of a better transmission in a diesel truck than in a gasoline version.

3. You are looking over your combine, getting it ready for harvest, and notice the aluminum radiator has several small pinholes and is beginning to leak. You smelled coolant when you put it away last year but thought nothing of it.

You pull the radiator out, and it has small holes in different places – some in the tubes and others in the tank. You figure it is best to get a new one. You do not know where the pinholes came from.

Which farmer is correct?

A: Farmer A says that the machine has a bad ground circuit, and it is causing electrolysis and making the holes.

B: Farmer B told you that mice and field rats are nibbling on the aluminum over the winter since you found a nest near one of the holes.

C: Farmer C is well convinced that the anti-freeze is bad and rusting the radiator.

D: Farmer D told you not to buy that “color” combine.

4. You were busy yesterday doing fieldwork, and it was hot out. The air conditioner in the tractor was not working too well, and you noticed that you heard the A/C compressor cycling on and off quickly.

You stopped in the field and got out and opened the hood. The compressor was kicking the clutch in-and-out every few seconds.

You got the work done, but it was not a comfortable ride.

Which farmer knows why the compressor was cycling so fast?

A: Farmer A says that the alternator must be weak and not supplying enough juice to the compressor.

B: Farmer B thinks the condenser is plugged with chaff and debris, and the system has no air.

C: Farmer C tells you the temperature control in the cab is bad and putting the heat on at the same time.

D: Farmer D insists that the A/C is low on refrigerant.

5. It is a cold winter day, and you are working in the shop, converting your planter over to electric drive meters.

You followed all the instructions and hooked the wiring harness up as stated. When you test run the system, you notice a few of the meters seem to be turning more slowly than all the others, even though they are all set for the same population.

There is no rush about fixing this, so you figure the next time you are in town you will bring it up at the coffee shop. You check the voltage to each electric motor, and it is OK.

Each farmer has a different thought.

Who is correct?

A: Farmer A tells you the wires may be too long, and the voltmeter is not telling the truth.

B: Farmer B says the electric motors must be made in China and are bad.

C: Farmer C says to look at the schematic and do a voltage drop test on the ground circuit of the motors that are running slowly.

D: Farmer D says that the tractor engine was running too slowly and the hydraulic flow to the planter’s alternator was not enough.


1: Farmer C is correct. The rating on a thermostat is the crack-open temperature, that is when liquid flow to the radiator begins.

Most thermostats take a further rise in liquid temperature of between 10 and 20 degrees Fahrenheit to become entirely open.

2: Farmer B is correct. Two things make a diesel engine more fuel-efficient. Diesel fuel has more BTU of energy per gallon than regular gasoline – approximately 134,000 BTU and 117,000 BTU, respectively.

Also, the higher compression ratio with diesel makes the engine thermally efficient; more chemical energy is converted to mechanical energy by the crankshaft.

The higher the compression ratio on any engine, regardless of the fuel, has a positive impact on fuel efficiency.

3: Farmer A has the correct reason. The combine has a weak ground circuit somewhere and is causing electrolysis. The electrons are finding ground through the coolant and are eating away at the aluminum.

If the ground is not repaired, the new radiator will fail in the same way.

4: Farmer D is correct. When a modern A/C system is low on refrigerant, it will cycle the clutch on-and-off quickly, and the duct discharge temperature will be high.

5: Farmer C knows the most likely reason. A DC circuit uses voltage and ground. If a ground circuit is weak, meaning it has a high resistance, then all the energy will not get to whatever the load is – in this case, the electric motors. A voltage drop test is the only accurate way to check a ground circuit. end mark

Ray Bohacz is the founder of FarmMachineryDigest and the “Idle Chatter” podcast. Learn more about him by reading 3 open minutes with Ray Bohacz. Contact him with your farm machinery question at Hot Rod Farmer.