Tier 4 Without Tears

By 2015 all new off-road diesel equipment will be Tier 4 compliant, requiring additional maintenance considerations.
Tier 4 Without Tears
Standards for off-road vehicles with engines of 25 to 74 hp will be implemented in January 2013, and 75 to 749 hp beginning January 2014 and concluding in January 2015. Canadian regulations are designed to mirror those of the EPA, but at slightly later implementation dates. (Photos courtesy of John Deere)

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Final Tier 4 (FT4) diesel engines standards have already been implemented for newly manufactured on-road vehicles with the 2010 EPA emission regulations, but the switch has just begun for off-road vehicles. Off-road diesel owners need to understand the specific maintenance needs of these engines, and where state or local end-user regulations may require them to use Tier 4 equipment.

Manufacturers must meet the EPA's FT4 requirements according to engine horsepower range. Standards for off-road vehicles with engines of 25 to 74 hp will be implemented in January 2013, and 75 to 749 hp beginning January 2014 and concluding in January 2015. Canadian regulations are designed to mirror those of the EPA, but at slightly later implementation dates.

However, John Deere Construction and Forestry Division Engine/Drivetrain product marketing manager Joe Mastanduno notes that while the EPA regulations for manufacturers don't apply to owners and operators, they still need to be aware of federal, state and local regulations that apply to end-users.

"The EPA has identified areas of non-attainment for ground level ozone and particulates," he says. "Counties and municipalities that are in non-attainment areas are enforcing their own regulations that cover diesel equipment in order to meet EPA standards. We're seeing individual counties and municipalities specifying what sort of diesel engines can be used in their jurisdictions, sometimes with a penalty for using older equipment that doesn't reflect what's available. Jurisdictions such as Chicago, New York City, Vancouver and Massachusetts are already advancing end-user regulations that mirror the availability of new equipment."

The EPA has also drafted Ozone National Ambient Air Quality Standards with tougher ozone requirements. While changes to the existing regulations are currently on hold, the EPA will begin reconsidering the ozone standard in 2013. Application of the standard could see more areas falling into the non-attainment category.

Interim Tier 4 roll-out complete

The final roll-out of current Interim Tier 4 (IT4) engines of all horsepower ranges was completed in January 2012, although existing dealer stock of older engine models continues to enter the market.

For those who are still anticipating IT4 equipment, the biggest changes involve the types of fluids required by the new engines. IT4 engines use only ultra-low sulfur diesel (ULSD). The oils used must be low-ash CJ-4 oils. All coolants and additives should be pre-approved to work with a specific engine.

Mastanduno notes that the EPA diesel rules are outcome based, so John Deere's approach to meeting regulatory requirements reflects its own technological choices. However, the approach taken by many other equipment suppliers represents the use of similar technology.

The heart of the changes to the IT4 engine is the exhaust filter which consists of a diesel oxidation catalyst (DOC) and a diesel particulate filter (DPF). The exhaust filter is designed to react with exhaust gases to reduce carbon monoxide, hydrocarbons and some particulate matter. While the DOC requires no user maintenance, the DPF must be replaced at minimum intervals defined by the EPA.

"The DPF cycles through a self-activating cleaning process called passive regeneration that uses exhaust heat produced during normal operating conditions," says Mastanduno. "In redesigning the engines, we focused a lot on the tolerance of the parts such as the clearance on piston rings and we were able to reduce oil burning to about one-tenth of what it used to be. However, because of ash created by burning lube oil in the diesel, it still requires the minimum service interval set by the EPA."

Servicing diesel particulate filters

The ceramic filter must be changed at a minimum interval of 4,500 hours for engines at or above 175 hp and a minimum interval of 3,000 hours for engines rated below 175 hp. Delaying that suggested maintenance schedule indefinitely will eventually cause the engine to shut off. Operators will have plenty of warning, however. One unique aspect of John Deere technology is the use of condition-based monitoring that alerts the user to when the DPF needs to be exchanged.

"A filter restriction bar on the control panel will show you that the exhaust filter is approaching the end of its service life," says Mastanduno. "A bar will turn to green, yellow and eventually to red as the filter goes into a high restriction state that gradually powers down the engine. These warnings aren't only visible to the operator – they can be sent remotely to desktop computers, forwarded by email or sent to a smartphone."

That same wireless link can be used to upgrade engine firmware or run diagnostic checks using a connection established between dealer and operator on specially-equipped John Deere models.

Mastanduno notes that dealer servicing is the best course of action for the ceramic filters. There are no generic filters or filters that are interchangeable between the various manufacturers of construction equipment.

"We also saw the emergence of mobile filter cleaning services, particularly in California, that promised to clean them out on the spot," he says. "They would install the cleaning equipment in vans and then drive to the site for service, but reports suggest that the filters were able to operate effectively for perhaps 250 to 500 hours instead of the 1,000 hours that was typically promised."

When dealer-serviced, the filter can be exchanged and the operator is given a core charge for the filter core, which can be cleaned through an exacting process involving pressurized air and high temperature baking. The filter must be handled carefully if removed by the operator – dropping it on the floor even from a low height will cause it to crack like a ceramic vase, rendering it irreparable.

Reducing nitrous oxide

The newest FT4 compliant engines, however, need to deal with the results of all of the changes to the engines made in IT4.

"A traditional diesel engine can't reduce carbon monoxide, hydrocarbons and particulates to the levels required by the EPA without creating nitrous oxide (NOx)," says Mastanduno. "They have different properties and as one decreases, the other increases. A more complete burn of the diesel creates more NOx in the exhaust, while a cooler burn creates less NOx, but more particulate matter. FT4 is designed to deal with the NOx created in the previous round of changes as a separate stream."

The reduction in NOx is achieved through selective catalytic reduction (SCR), a process that uses a surface coated with precious metals to convert NOx to nitrogen and water.

"It's a catalytic process, so there isn't anything replaceable inside the unit," says Mastanduno. "However, the process requires the use of diesel exhaust fluid (DEF) in a separate tank. The fluid is injected into the exhaust stream to help reduce NOx, converting it again to nitrogen and water. Although we've seen DEF offered more and more widely, we recommend that the tank be topped up at the same time as the diesel tank is filled. You don't want to be working out in the middle of nowhere and run out of DEF."

Operators of IT4 and FT4 equipment should see little change in day-to-day operations, other than the addition of new dashboard engine monitors. However, Mastanduno says that maintenance shop staff will find engine components more tightly packed inside the engine compartment.

"As you oversize some components to create cleaner exhaust, and add other catalytic components, you eventually run out of room," he says. "To get the heads off most of the engines will now require you to remove the DPF prior to starting work."

Mastanduno notes John Deere continues to offer compact excavators that are not subject to IT4 or FT4 requirements. "If you can bring the machines down below the horsepower breakpoints, they are subject to different emission regulations," he says. "By using different machine integration techniques, we've been able to take some excavators that serve this market down below the power band breakpoint and have avoided the requirement to add DPFs to these machines."

Tier 4 Diesel—The Retrofit Route

In areas where end-user regulations have pushed operators to adopt Interim Tier 4 (IT4) and Final Tier 4 (FT4) technology, some operators have opted to take the retrofit route, rather then buying OEM machines.

“It was possible to add a diesel particulate filter (DPF) on existing Tier 2 and Tier 3 machines, but in California we were getting anecdotal information of diesel filters being slapped onto the top of the hood and affecting operator visibility,” says Joe Mastanduno with the John Deere Construction and Forestry Division. “Operator safety was one of the reasons that California slowed down end-user requirements in that state and gave operators a four-year break on adopting the new technology.”

However, reducing particulate matter with retrofit DPFs has proven difficult. With retrofit DPFs, for example, the DPF computer often fails to communicate with the engine computer.

“We’ve been in development with a supplier to provide retrofit DPF support in the form of a complete Tier 4 retrofit package and even with considerable research and development, it’s proved to be very challenging,” says Mastanduno. “While the technology of the components is well understood, you need to be able to guarantee that they are all seamlessly integrated and work as a complete system. Attempting that at the shop level and achieving local end-user regulations would present a huge challenge.”



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