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Why Kukje Diesel Tractor Engines Are In a Class All Their Own

We want to help you understand everything you need to know about Kukje diesel tractor engines and what puts them in a class all their own.

And as a quick aside --- we are here to help you purchase a new tractor, parts and implements when the time is right.

Let’s get started.

Kukje Introduced

The Kukje engine is the best diesel engine available in any tractor from any manufacturer. And you likely never heard of them.

Right now this engine is featured in the TYM Tractor T474, T494 and T574 models.

When we say it is the best diesel of all --- we mean it and will back that statement up.

To get started --- let’s dive in and discuss emission systems and modern diesel engines. (This review only applies to diesel tractors in the 40-59hp range.)

Fuel Injection

Various manufacturers have had lots of ideas on how to inject diesel fuel into a combustion chamber.

There are two common methods in modern tractors.

Most mechanically fuel injected diesel engines have one high pressure fuel injection pump. It compresses the fuel and sends it to each of the cylinders individually. This is the most common way of making diesel engines work.

To meet emissions criteria --- tractor manufacturers use High Pressure Common Rail Fuel Injection. A single high pressure pump pressurizes the whole system. Each injector is tied to this “common rail.” Electronically-controlled injectors release the high pressure fuel into the cylinders. It is a great technology and offers many benefits.

Compared to mechanical systems, it falls severely short.

To make common rail work --- you need an ECM, a high pressure fuel pump, multiple sensors, electronic injectors, and a wire harness that ties it all together. If one of the systems fails --- the engine will be severely hindered or may not run.

This is a lot of complex systems to pack into a tractor that is exposed to mud, dirt, rain, and snow.

This system is also difficult to troubleshoot and repair. You must use expensive diagnostic software.

Mechanical fuel injection pump engines have not changed much. Once the battery has started the engine --- it runs without using any electricity --- if you have fuel.

Modern mechanical engines do have some conveniences such as oil shutoffs which protect the engine and save you big money if you ever run low on oil.

Those are the two basic "hearts" of a diesel engine.

Now let’s discuss emissions.


EGR valves return a portion of the engine exhaust back to the intake and reburn and reduce emissions.

They usually have EGR coolers. They cool the hot exhaust air before it reaches the intake. The valves are prone to carbon buildup, as well as mechanical and electronic failure.

EGR coolers can rot out or leak internally. This can push coolant into the engine. This causes a coolant leak. And these leaks are hard to spot.

The questions arise --- “Is the coolant going straight into the engine via a cracked head or bad head gasket? Is it merely a faulty EGR cooler?”

When this happens you need to have a skilled mechanic to properly diagnose it. You do not want to replace your head gasket when all you need is an EGR cooler.


Here are three acronyms you need to know:

  • DOC (Diesel Oxidation Catalyst)

  • DPF (Diesel Particulate Filter)

  • DEF (Diesel Exhaust Fluid)


DEF systems inject a urea solution into the passing exhaust gasses which lowers the NOX emissions. These systems are complicated because they involve DEF tanks, pumps, DEF injectors, NoX sensors, and heaters.

DEF can turn into a slush in cold temperatures --- so it needs to be kept warm in cold weather.

This further complicates the systems because they need to either have electrical heaters or heat exchangers. Both run on hot engine coolant.


Both DOC and DPF are supposed to reduce particulate emissions from diesel engines.

DOCs are like a car’s catalytic converter. They don’t do much and go un-noticed until they plug up and need to be replaced. They do not regen --- while DPF’s need to regen.

Regen is short for “regeneration.” This is the process of cleaning soot out of a DPF.

The engine runs at a high rpm (usually around 2,000 for tractors) and once everything is at the correct temperature --- an additional injector mounted between the exhaust manifold and the DPF injects diesel directly into the exhaust system. This creates heat and pressure that cleans out the DPF.

Regens need to be performed when the onboard systems detect the filter is getting full. Compared to DEF systems --- DPF’s are rather basic.

A differential pressure sensor tells the computer when the filter is full. The temperature sensors monitor the system to make sure nothing overheats. And the additional injector sends diesel in the system until it is cleaned out.

Emissions System Implementation

Tractors that use a common rail engine have an ECM that controls the function of the engine.

The ECM also controls the emissions systems. When the systems sense a plugged filter --- a malfunctioning sensor, or any other problem --- they illuminate the check engine light or DPF light.

If you ignore the lights, the engine will eventually derate. This means the ECM sensed an issue. It wasn’t addressed. It will try to protect the engine by not letting you use it.

You might be able to idle and move around --- but you won’t be able to do any work. The only way to fix a derate on a common rail engine is to have the manufacturer’s software to reset the system or further troubleshoot what’s causing the problem.

40hp Class Tractors

Kubota L4701 uses the Kubota V2403-CR-E4 motor which uses an electronically-controlled common rail fuel system. It has a non-cooled EGR valve and both a DOC and DPF.

John Deere 5045E uses the PowerTech 3029H motor. It uses an electronically-controlled common rail fuel system with both a DOC and DPF --- but no EGR valve.

Mahindra 2645 uses a Mahindra motor. It uses an electronically-controlled common rail fuel system. It has an EGR valve and only a DOC.

The Kioti DK4510 uses the Daedong-Kioti 3F1863T-45 motor. It uses an electronically-controlled common rail fuel system, has a cooled EGR valve --- and both a DOC and DPF.

LS XR4510 uses the LS Mtron L3C19-T motor which uses an electronically-controlled common rail fuel system, has a cooled EGR valve --- and both a DOC and DPF.

New Holland Boomer 45 is essentially the same tractor as the LS and uses the same motor and systems.

And finally, the TYM T474 uses the Kukje motor which has a mechanical fuel injection pump and a DPF.

Mahindra mCRD Engines

Mahindra tractors are regen free.

However --- with Mahindra you get all the complexities of an electronically-controlled common rail engine. It’s prone to sensor, harness, and computer failure.

While it doesn’t have to regen --- it still has a DOC which is like the catalytic converter on your car.

It will get plugged up eventually. The only thing you can do is replace it. With emission rules tightening up every year, it is only a matter of time until Mahinda is also forced to use a DPF.

Kukje Tractor Diesel Engines

The Kukje diesel engine is superior as it uses a mechanical fuel injection system.

From all the research --- it appears that the Kukje is the only mechanical diesel engine in tractors of 40-59hp.

This tractor will start and run without any electronic controls, sensors, or computers.

The DPF system on Kukje motors is supplemental. This motor has its own computer and control system that are separate from the motor.

There is no diagnostic software for the Kukje motor. It doesn’t need it.

When the DPF “full” light comes on --- you will still need to perform a regen --- but the process is infinitely simpler than the others.

Common rail engines have their place. They are quieter, more fuel efficient, and “smell” less.

When it comes to a tractor --- simpler is better. That’s why the Kukje is the best of both worlds.

The Kukje is a simple mechanical engine --- and it also has a DPF which significantly reduces smoke and particulate emissions.

DPF systems get a bad rap from misinformation or improper operation.

When you start up a 26hp tractor with no DPF --- you will experience a lot of smoke and smell the diesel quickly. Engines with DPF systems do not have these issues. These systems aren’t only in place to protect the environment --- they also protect the operators.

While operating a tractor --- you are breathing in the exhaust. DPFs allow you to breathe in cleaner air. This is super important.

You might be wondering why Kukje isn’t well-known. Is it inferior equipment? No way.

Kukje has been making diesel engines since 1968. For a while they made John Deere tractors under contract. At another point --- they made Cummins A series engines under contract for Cummins. Yes they made Cummins engines. Kukje made the A series for them.

Compare a Kukje motor against any other competitor’s motor --- and the result will be clear.

Hopefully, this brief article has helped you better understand the excellence of Kukje motors and why you should consider the TYM Tractors models that feature them.

If you need any further help or have any questions about Kukje engines, tractors, implements, or anything else equipment-related, please contact your dealer, local mechanic, or call us at 602-734-9944. Please ask about our current new and used tractor supply.

If you are looking for old, vintage, classic, or new tractor parts, send us a part request.

Team Tractor Ranch - #1 Tractor Dealer in Arizona. We sell and service most major brands of tractors including Yanmar, Kubota, John Deere, TYM, Mahindra, Kioti, Case, New Holland, Massey Ferguson, Ford, Deutz, Case IH, Farmall, International Harvester, Branson Tractors, LS, Shibura, Claas Tractor, McCormick Tractors, Valtra, Solis, YTO, Montana, and Nortrac.

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Michael Buck
Michael Buck

What a great article I learned a lot. I bought Mahindra tractor and was told it had a Mitsubishi engine. Its a 2021 2638 37.4 HP 4 Cylinder engine. The engine plate is not Mitsubishi but It was made by TYM.The tractor metal plate says TYM assembled. For the motor is it s Yanmar or a Kukje? Please help if you can I am sending in the engine block numbers. The numbers read



Please let me know if you know at thanks for help

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