Situation No. 1

Your liquid-cooled UTV started to run hot, according to the gauge. You checked the water pump, drive belt, radiator and coolant levels, and all seemed fine. You decided to change the thermostat in the hope that this is the cause.

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The parts man at the dealership hands you the proper thermostat, and you notice it has stamped on it “180.” You ask the counter man 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.

Situation No. 2

You are thinking about investing in another self-propelled sprayer for the farm. You do not want to buy a new one since this unit will only be used for foliar feeding and fungicide application. You had a bad experience a few years back when you seriously dinged-up and killed some crop due to herbicide residue. You vowed to eventually get a dedicated sprayer for in-season crop care and nutrition.

You found a beautiful unit a few towns away. The seller said it worked well until recently when the pressure would not stay steady. He felt it needed a new pump and priced the sprayer accordingly. You agreed with his diagnosis and took the unit home.

Upon removal and disassembly of the centrifugal-style pump, you noticed the housing was pitted internally, and the tips of some of the impeller fins were broken off. 

Confident you found the issue, you bolt on the new pump and hit the field … only to see that the same pressure problem exists. Perplexed and frustrated, you ask around for some advice, and this is what you receive.

A: Farmer A says the new pump is defective and has the same problem as the one you replaced.

B: Farmer B believes the gauge is wrong, and the old pump was fine.

C: Farmer C says the old pump ate some dirt from the tank, and it must still be in the system, which is why the impeller is damaged and the volute pitted internally.

D: Farmer D is adamant the original pump was damaged by cavitation, and that is why the pressure is jumping around. 

Situation No. 3

It is cold out for this time of year. There is not much to do today on the farm, so you drive into town to have coffee with the guys and catch up on local gossip. Before you finish your first cup of coffee, you brag about what a good husband you are; you warmed up your wife's car for her before she left to teach school in the next town. You also warmed up your pickup, not for comfort, but since it is better for the engine.   

Some of your buddies have a different opinion. Who is correct about warming up an engine?

A: Farmer A says that by idling the engine until it makes heat, you are decreasing the wear, and it is the smart thing to do if you want all your equipment to last.

B: Farmer B argues that it is the worst thing to do – you are wasting fuel and accomplishing nothing. When corn was $8 per bushel that was fine, but with $3.50 corn, you are crazy.

C: Farmer C is firm in stating by warming up an engine, you are creating excessive wear.

D: Farmer D claims it makes no difference what you do – all these new engines are junk and will not last like the old JD 4020 and 1972 Ford did.


Situation No. 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 10ºF and 20ºF to become entirely open.

Situation No. 2: Farmer D is correct. There is an issue with the plumbing – either to the pump or from it to the boom that is causing cavitation erosion. The clues are the pitted volute (housing) on the pump and the broken tips on the impeller. Due to the restriction, air bubbles are forming that destroyed the pump. If you do not find the problem, the new pump will be damaged in short order.

Situation No. 3: Farmer C is correct. Letting an engine idle to build heat exposes it to excessive wear. With a gasoline engine, the rate of fuel vaporization is poor. In a diesel, the cold cylinder wall does not provide enough heat to burn all the fuel. In both examples, the oil becomes fuel-diluted, and carbon deposits form on the piston crown and backside of the intake valves. Also, all other engine parts are cold and experience excessive wear, as much as 1,132% by some tests.

The best procedure is to start the engine, and as soon as oil pressure is up (one to two seconds), drive the vehicle or equipment away under a light load. This will significantly decrease the amount of time the engine sees excessive wear since heat will be built faster. As an aside, this also brings the entire driveline up to temperature. Idling the engine only puts some heat into the engine block and not the rest of the driveline.