John Deere diesel tractors are some of the best small farm tractors and a fantastic addition to any farm, and once you have a tractor with a bucket loader, you’ll wonder how you managed without one. But just like any equipment, they do break, fail, and let you down from time to time, but the good news is that most running problems in diesel engines are generally one of four problems.
But First, A Quick Primer on Combustion
Combustion is the process of burning something, or more technically, a rapid oxidation of fuel that releases energy exothermically. All combustion engines rely on the energy that is created when the fuel they use explodes (combustion) inside their cylinders, pushing down on the piston and causing the crankshaft to go round and round. To achieve combustion, three things have to exist, commonly referred to as the combustion triad: fuel, air, and ignition. Without these three elements, your engine would not work, your furnace would not produce hot water, and your wood stove would not produce heat, so this theory applies to both your best farm tractor and your machinery, as long as fuel is burned to produce. Energy.
In a combustion engine, there are two types of ignition sources, which are electronic ignition (spark), as seen in gasoline engines with spark plugs, or compression, as in diesel engines. A diesel engine compresses both fuel and air that it creates heat, causing the mixture to ignite and causing this exothermic reaction that makes these engines go round and round. Fortunately for us, unless your diesel tractor has been very neglected, beaten to death, or is very cold, we don’t need to worry about the ignition part of that triad.
Typical Tractor Diesel Problems
The starter motor: If you turn off your tractor, or it has been idle for a while and you are going to start it but you hear that clicking noise instead, then you have a starting problem. That problem may simply be a dead battery that needs a jump, a corroded connection between the starter and the battery, or your alternator (or generator) is not charging your battery.
The starter motor is a small electric motor with a gear that turns the motor, and to do this you have to turn that gear and push it out to engage the teeth of the motor flywheel, so if you hear a quick buzz without that the engine is cranking, then the starter is not engaging the flywheel. The most likely cause is a stuck solenoid preventing the gear from being pushed towards the flywheel. Almost all manufacturers say that the solenoid should not be struck when it is believed to be stuck, but a quick blow with a hammer has saved me from coming home many times. If a blow to the starter doesn’t fix the problem, then it’s time to buy a new starter. However, if your starter doesn’t make any noise despite having a good battery or jump leads, check to see if the starter is getting power. The most common causes of a lack of power to the starter are blown fuses, bad key switches, and dead relays.
If your engine spins but cannot draw in air, it cannot achieve combustion. Without combustion, there is no power, plain and simple. Check the air filter to see if it is clogged with sand, dirt, or dust. Make sure the rodents have not made a nest in the air intake and make sure there is a free passage from the filter box to the engine.
Cold Engine Block
Even the best small farm tractor diesels don’t like to be cold, period. Cold cylinder heads have a hard time generating enough heat to achieve ignition, which is why some engines have glow plugs, hot air induction units, and possibly block heaters.
The glow plugs are small electric heaters that screw into the cylinder head in a similar way to spark plugs, but they only create a little heat to heat the cylinder head, not to cause combustion. They burn out from time to time and need to be changed every few years, depending on the frequency of use.
Hot air induction, or hot air boxes, are common on newer tractors and basically consist of a heating element in the air intake system. When activated, the unit preheats the air entering the engine and raises the cylinder temperature enough to cause combustion. Check the user manual of your tractor, as it is not normally an automatic system, but a manual system that you have to activate. On my John Deere 5105, you have to press and hold the key for 3-5 seconds, then turn the key to start the engine.
Some of the best small farm tractors sold in cold climates have a 110v plug near the engine block to supply electricity to a small block heater. This heater keeps the engine coolant somewhat warm so it can start in very cold environments, but it is intended to be plugged in overnight, not 5 minutes before you need to start it. If the block is so cold that it won’t start, plug it in and wait an hour or two. If we wait for a very cold night, we plug in our tractor and leave it overnight in case we need it to clear snow or run our generator if we run out of power.
In the worst case, spray some silicone lubricant on the tractor’s air intake (without the air filter) and try to start it. The silicone spray will ignite before the cold diesel, so if it does get started, the cylinder heads will get hot enough to run on diesel. Do not use ether spray to start a diesel tractor.
Fuel delivery problems are the most common when it comes to a diesel engine that doesn’t work. These are the most common fuel supply problems found in diesel engines:
Unlike gasoline, diesel turns to a gel at about 17.5 Fahrenheit and does not flow through fuel lines. Even if the block heater is on, the fuel tank, lines, and filter can get cold, so be prepared and have a bottle of diesel blender like Power Service’s Diesel 911 product. Products like these can be hard to come by at times, especially in cold weather, but look at your local farm store, auto parts store, and nearby truck stops and grab a bottle or two just in case, as it should be in your list of farm tools and equipment to keep on hand.
Follow the directions on the bottle, but most products work quickly by pouring a little into the tank and fuel filter. Speaking of fuel filters, when diesel oil gels, the wax in the fuel separates from the rest of the fuel and tends to coat the fuel filter, rendering it unusable. Be prepared to change the fuel filter when your tractor gels up and make sure you have one or two on hand. Big thanks to Walt, the local mechanic, for the waxed filter track.
Sometimes in warmer months, diesel and especially biodiesel can experience biological contamination resulting in a dark, viscous sludge in the fuel tank and fuel lines. This sludge, normally caused by algae growing on fuel, clogs fuel filters and reduces fuel flow. Many companies make a biocide product for fuel to control this. If you store fuel on the farm, be sure to treat your storage tanks as well as your tractor’s fuel tank if this occurs.
What do you use to store diesel? Is it an old tank? Are you letting water in? Is it rusting inside? We have a 300 gallon fuel tank that we keep the diesel in on the farm and recently we realized that it has been contaminated with all kinds of things. We have had to drain and inspect the tank and add fuel filters to our fuel transfer pump to prevent more contaminants from entering our tractor tank. If you find yourself with a heavily contaminated fuel tank on your tractor you may have to drain and flush your tank, as well as clean your fuel lines. I use an air nozzle on my compressor to blow out clogged fuel lines when this happens.
Water in diesel fuel can be deadly to an engine. Due to the high compression in the cylinder heads, the introduction of water with the fuel can destroy the piston heads. This is why most diesel fuel filters swell immediately when they come into contact with water, functioning as a kind of shut-off valve. Since water is heavier than fuel, if you drain your tank sump (the bottom) and find water after your tractor has mysteriously stopped running, then blow the fuel lines back into the tank, drain the water and replace your filter before starting again.
Air is an important part of the combustion triad, but in a diesel fuel line, it wreaks havoc on starting ability and performance. Every time a line is broken (a connection point is opened) air can be drawn into the system. If there is a leak in the lines, you may also be sucking air into the high pressure lines, so find the leak and repair the line.
After performing any maintenance that requires removing the fuel filter, opening a fuel line connection, or blowing out a low pressure supply line, you must prime the line (fill it with fuel). Unlike electric fuel pumps in gasoline applications, the air must be evacuated for the engine to run. Some tractors have a hand pump near the fuel filter that allows you to draw fuel from the tank and into the filter box. If your filter housing has the hole facing up, as in most applications, you can make your life easier by filling the filter with diesel before installing.
Now that the low pressure side of the fuel system is primed, you need to bleed the high pressure injection lines coming from the injector pump and going to the injectors themselves. Most diesel engine manufacturers offer the “crank and crack” method, which is the typical method of trying to start the engine, which runs the pump, and “crack” or unscrew the connection between the line and the injector. with a wrench just enough to let the air out and a small jet of fuel, and then tighten it again. Do this with each injector and you should be able to start the engine. This method is time consuming and requires two people, one to turn the key to start the engine and one to open the lines.
Farmers and mechanics work alone most of the time, so it should come as no surprise that there is an easier way to do things. Some mechanics connect a remote start switch with a wire so they can do both jobs at the same time, but if you can get to the air intake and the key, you can use a can of silicone spray to start your tractor. On my best small farm tractor, I can raise the hood, remove the air hose from the intake manifold, and spray some silicone spray on the intake and start the engine at the same time. The silicone spray acts as a temporary fuel source, which keeps the engine running and if you give it a little spray every time the engine starts to stutter, you can keep it running until it purges the air from the fuel lines. itself. Use this spray very sparingly, excessive use can damage your engine so use at your own risk. Do not use “starting fluid” ether spray instead of silicone spray, it is not good for modern diesel engines and is more likely to damage the engine than to help you start.