Service Tips: Tier 4 Final-compliant engine compliance

Perkins Engine Co. Ltd.'s engine expert Andy Miller shares common concerns and confusion associated with operating Tier 4-compliant engines. 

by Andy Miller

It’s no secret that the diesel engines used in the industrial and construction industries have become increasingly complex over the last decade and a half. There are a several reasons for this but a key one is governmental regulations that aim to reduce the emissions output of diesel engines.

Perkins Tier 4-compliant diesel engine with DEF tank
In the United States and European Union, the emissions standards are referred to as U.S. EPA Tier 4 Final and EU Stage V. At their core, these standards require diesel engine manufacturers to develop cleaner engines.

In the United States and European Union, the emissions standards are referred to as U.S. EPA Tier 4 Final and EU Stage V. At their core, these standards require diesel engine manufacturers to develop cleaner engines.

To meet or exceed these requirements, diesel engine manufacturers have designed or updated engines with new technologies such as enhanced common rail fuel systems, exhaust gas recirculation and aftertreatment systems. Almost all new equipment sold in the United States or European Union with power ratings greater than 25 horsepower will likely have one or more of these technologies in place.

What does this mean to the rental company, owner operator and end user and are these systems reliable? Can the rental company continue to service and maintain this equipment, and how does an end user safely and efficiently run this new equipment without causing issues? 

The first step is to have a general understanding of what technology is being used on the engine. Technologies you may see on engines, including Perkins, include:

• Common rail fuel system Delivers fuel precisely at the time needed for injection and at extremely high pressure. This ensures a high level of atomization. The smaller the injected fuel droplets, the cleaner the exhaust gases will be leaving the engine.

• Exhaust gas recirculation (EGR) Takes a portion of the exhaust gas from the exhaust manifold and directs it back to the intake of the engine. This helps reduce NOx from the combustion process.

• Diesel oxidation catalyst (DOC) This filter is normally the first filter in the aftertreatment system. It is a flow-through filter, meaning there are small passageways that the exhaust flows through from the inlet to the outlet. As the exhaust flows through this filter, it reduces CO and CO2, which will help the downstream filters be more efficient and helping the engine run more efficiently as well.

• Diesel particulate filter (DPF) This filter’s main purpose is to remove particulate matter or soot from the exhaust stream. It is a wall-flow filter meaning the exhaust gases are forced through a porous material that traps particles that flow through it.

• Selective catalytic reduction (SCR) filter This is generally the final filter element in an aftertreatment system. It works in conjunction with a diesel exhaust fluid (DEF) system to reduce NOx emission from the exhaust gases. DEF is sprayed into the exhaust gases exiting the DPF. As the mixture of DEF and combustion gases pass through the SCR filter, NOx emissions are significantly reduced, and cleaner exhaust gases exit the tailpipe.

• Diesel exhaust fluid (DEF) system: This unit consists of a tank, pump, filter, lines and injection unit to transfer DEF from the tank to the aftertreatment system.

Perkins and other manufacturers have gone to great lengths to make these new systems as transparent to customers as possible. However, there are a few things that customers need to understand when operating or maintaining equipment with these newer engine technologies:

Fuel cleanliness and maintenance
Diesel fuel must meet a strict 15 parts per million (ppm) sulfur level and be kept clean and free of water and moisture.

Sulfur is naturally found in diesel fuel; however, when it is burned, it collects in the diesel particulate filter as an ash substance. These filters have been designed with this in mind, however, if higher sulfur fuel is used, the ash material will accumulate faster than desired, requiring premature maintenance. If using 15 ppm fuel, most DPFs used on Perkins engines will not need cleaning for the life of the engine. 

As the common rail fuel systems operate under high pressures, they are sensitive to dirt or water in the fuel, which may lead to fuel injection problems. Also, the filter systems may plug prematurely causing increased maintenance and downtime.

DEF handling  
Cleanliness, storage and proper filling procedures are key to maintaining system health.

Diesel exhaust fluid (DEF) shouldn’t be intimidating. As long as the fluid is kept in a clean environment and stored in a cool, dry location, it should function as intended.

If dirt or other contaminants are introduced into DEF or other fluids such as fuel, oil, coolant or water are mixed with DEF and introduced into the DEF system, damage may occur to the system. This is often costly and time consuming to repair. It should be the first point customers must understand when using equipment with Tier 4-final-compliant engines.

It’s also very important to understand where the DEF filling location is on the machine. This is one of the bigger maintenance issues such as accidentally filling the DEF tank with some other fluid such as fuel, washer fluid or coolant. Only clean, pure DEF should be put in the DEF tank. It is almost always located next to or near the diesel fuel fill.  

Run it hot
Proper machine operation ensures optimum aftertreatment performance. One thing that may come as a surprise is that the filters found in the aftertreatment system function much better when they are hot. The heat generated by the engine will help the DOC convert the carbon monoxide (CO) and carbon dioxide (C02) gases. It helps the DPF remain clean by burning off the accumulated particulate matter or soot and it helps the SCR filter more efficiently convert the NOx gases.

When an engine has idled for long periods of time or have only run for short bursts and are then shut off, these conditions may not create enough engine heat to get the aftertreatment system to operating temperature. It is very important to understand how you will be using the machine or engine and make sure to plan for periods of time where the engine can be exercised under load or operated at high idle for at least 30 to 45 minutes per shift to allow for the system function as intended.

Because you may find maintaining higher regulated power systems like those under Tier 4 Final or Stage V standards complex, Perkins is supporting the off-highway rental industry through its rental support program ( The program offers direct access to parts, maintenance manuals, training and more, including 56 service training courses covering diagnostic processes and service tool training. It also covers a Perkins engine series of training tailored for service technicians.

It only takes a few minutes to familiarize yourself with the newer engines and aftertreatment systems and the more complex maintenance that will require the in-depth training that Perkins is offering. The more you know what you can control, the more you could save in costly repairs and maintenance downtime.

Andy Miller is product and technical training manager at Perkins Engine Co. Ltd.

The article orginally appeared inthe July-August 2020 issue of Pro Contractor Rentals magazine. ©2020 Urbain Communications LLC. All rights reserved.