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Mechanics Corner: Today’s wheel loaders require special care

Allison McNeal for Progressive Dairyman Published on 11 September 2017

Since wheel loaders are often a staple machine on many dairy farms today, it’s critical for producers to understand the machines are not designed like they were 20 or even 10 years ago. They require special care, particularly the diesel engine and emission systems.

Improving air quality and reaching today’s emission standards for wheel loaders started in 1994. Today, most wheel loaders in the U.S. are Tier 4-compliant, changing the way they emit engine exhaust in the atmosphere. The goal of the emission standards for wheel loaders has been simple: to lower harmful exhaust emissions, such as particulate matter and nitrogen oxides (NOx), to help promote clean air and to maintain a sustainable environment.



Reaching Tier 4 compliance has presented some challenges for manufacturers, including incorporating new technologies to meet the strict standards.

Evolving technology

Wheel loaders have gone through five different emission tiers, ranging from Tiers 1 through 3, interim Tier 4 and now Tier 4. As they transitioned to Tier 4 compliance, the development of more efficient technologies led manufacturers to promote improved machine performance, better fuel economy and longer engine life.

Moving to Tier 4, agriculture producers will likely experience enhanced machine performance, and the fuel economy is much better than earlier iterations. Producers are getting a great-performing machine powered by a fuel-efficient diesel engine.

Multiple technologies – ranging from mechanical fuel-injection systems to electronic injection systems – have been incorporated in various tier levels to help meet increasingly strict EPA emission standards. Technologies such as an electronic control unit, a high-pressure common rail system, diesel oxidation catalysts and diesel particulate filters were added to help reduce particulate matter (PM), leading to cleaner exhaust.

With today’s Tier 4 requirements, many non-road machines have an additional system called selective catalyst reduction. Selective catalyst reduction uses an ammonia- and water-based liquid called DEF.


Combining exhaust with DEF causes a chemical reaction that converts NOx into harmless nitrogen and water vapor. Tier 4 emission standards reduce PM and NOx emissions by approximately 90 percent.

In addition to the engine technologies and after-treatment systems, diesel fuel refiners started to produce ultra-low-sulfur diesel in 2006. According to the EPA, ultra-low-sulfur diesel is 97 percent cleaner than diesel fuel refined prior to 2006. Producers should be aware of how to properly store ultra-low-sulfur diesel in bulk storage tanks to avoid potential contamination in the diesel fuel and eventually in their wheel loaders.

Newer fuel filters for wheel loaders are designed to prevent contaminants in diesel fuel from reaching the engine and potentially causing damage that can be expensive to repair. It is recommended wheel loader owners regularly clean their bulk diesel fuel storage tanks and work closely with their local fuel provider to verify the quality of the fuel before it is added to equipment.

Producers should review their wheel loader operation and owner’s manual for recommended oils and filters for their Tier 4-compliant machines. The more consistent producers are about following extended maintenance schedules, the better off they will be. The machine will run more smoothly, helping them minimize machine downtime in the long run.

If recommended selective catalyst reduction maintenance are not followed, the NOx levels may not be compliant with Tier 4 emission standards, resulting in the requirement for a machine’s diesel engine to be de-rated until the issue is rectified. If schedules are not followed, component wear will increase, meaning expensive repairs will come earlier in the machine’s life.

At each oil change, oil samples should be taken to show unusual metal content, which may result in engine failure. Pre-failure component repair is generally less expensive than repairing after failure.


Importance of diesel exhaust fluid

DEF is a colorless, non-hazardous chemical that has been incorporated in most 75-horsepower engines and higher to help meet Tier 4 emission standards. The aqueous solution consists of 67.5 percent deionized water and 32.5 percent pure urea and is susceptible to variations in hot and cold temperatures, so keep this in mind before storing DEF.

  • Store the fluid out of direct sunlight.
  • Is the fluid stored between 12ºF and 86ºF (-10ºC and 30ºC)?
  • Is the fluid stored in an airtight container?

If you answered “yes” to all three, then you are taking the necessary steps to properly store DEF. When the fluid is exposed to extreme heat and direct sunlight, it can shorten its shelf life. One thing to note is: DEF inside wheel loaders can freeze. To thaw DEF tanks and supply lines, engine coolant is used to heat them in sub-freezing temperatures.

Operators should also be cautious when storing DEF to help reduce contaminants such as dirt and dust when working in earth-moving applications. Operators should try to fill the DEF tank directly from the DEF container. If you are using a funnel or intermediate containers, make sure to keep the container clean and only use the container for DEF.

Contamination can damage the catalyst in your selective catalyst reduction system and can cause you to use more DEF than you need.

Purity and concentration are critical with DEF, so be sure to work with your local dealer to better understand how to store and handle DEF fluid.  end mark

Allison McNeal is a technical writer with Two Rivers Marketing out of Des Moines, Iowa.