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Maintenance is a bit different for a natural gas truck

By on January 16, 2014

Every few years, trucks change in a way that requires rethinking on the part of drivers and preparation within the industry. Think of the transition to ULSD and the addition of DEF. Now, natural gas looms as the next big thing, and the number of vehicles using it will increase significantly in the near future.

UPS, for example, plans to purchase 1,000 LNG (liquefied natural gas) tractors by the end of 2014, making it the biggest private LNG fleet in the U.S. The company has been successfully operating natural gas vehicles for more than 20 years.

“We have not had any negative feedback from drivers about power, performance or handling on our LNG vehicles,” says Bill Brentar, UPS Director of Maintenance and Engineering. “There is very little difference between a diesel truck and an LNG truck. The biggest difference drivers may find is that they may need to adjust the range in which they shift at different points based on the rpm, and there may be slightly slower acceleration on a spark-ignited LNG vehicle.”

For the driver

Natural gas trucks tend to be more reliable than their diesel counterparts, and that means less downtime. Also since these vehicles burn a cleaner fuel, they have fewer emissions components. There is no diesel involved, so there is no need for diesel particulate filters or a selective catalytic reduction system. That reduces maintenance time as well as vehicle weight.

However, there are spark plugs and coils that ignite the fuel to contend with. Spark plugs need to be replaced on a regular basis, determined by engine hours, and the valves in spark-ignited natural gas engines tend to need adjustment more frequently than in diesel engines.

Natural gas engines run hotter than diesel, so they require a different type of motor oil. It must be changed every 15,000 miles — about twice as often as diesel engine oil. As with diesel engines, oil drain interval is duty cycle dependent, so it’s important to consult the owner’s manual.

For the technician

Most preventative maintenance tasks are the same for diesel and natural gas trucks. The fueling system obviously differs, so truck service technicians need training on how to diagnose and fix any problem in a natural gas fueling system. The Natural Gas Vehicle Institute (NGVi), based in Las Vegas, provides technical training and consulting on natural gas vehicles for companies in transportation, and teaches safety precautions for routine services like tire rotation, replacing a light or oil changes.

CNG, compressed natural gas, is stored under extremely high pressure — 3,600–4,200 psi — so techs must be aware of all of the high pressure components they are working around. LNG is extremely cold. It will burn skin on contact, so techs need to have proper equipment when working on LNG trucks. Because it’s so cold, there’s no odor to it, so methane detectors are needed in service bays to detect leaks.

“TA and Petro truck service bays are being retrofitted to handle any natural gas vehicle,” says Brian Lukavich, TA Truck Service and Petro:Lube Parts and Service Program Manager. “The key areas we’ll focus on will be electrical, ventilation, heating and adding methane detectors. This will bring our service bays in line with industry standards and regulations to service natural gas vehicles. We also are working with NGVi to provide safety training to all employees and maintenance training to our technicians.”

General safety concerns

While precautions must be taken with natural gas vehicles that are not taken with diesel vehicles, that is not an indication that the fuel presents a higher level of danger. In fact, natural gas is less likely to combust than diesel. Natural gas is in wide use to heat homes all across the country, and there are already about 120,000 natural gas vehicles in operation in the U.S. trucking industry.

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