The new EPA emissions standard for large diesel engines doesn’t just impact those in the market for a new motor coach. RVers who use diesel pick-ups to tow fifth-wheels and travel trailers also need to know about the regulations, which took effect January 1, 2010.
Since the 1970s, the EPA has lowered the allowable amount of gases like carbon dioxide and nitrous oxide in diesel exhaust. In an effort to further protect the environment and the people who live in it, the newest mandate requires diesel engine manufacturers to achieve near zero levels of nitrous oxide and particulate matter.
The issue of particulate matter, the solid and liquid droplets found in exhaust, is easily addressed with better filters. Diesel engines have come equipped with particulate matter filters for over ten years. The new standard requires a redesign that catches more of the soot and droplets so the standard is met.
Reducing nitrous oxide levels is bit more complex. One method used to achieve lower emissions is EGR – exhaust gas recirculation. This process redirects part of the exhaust back into the engine where the cooler gas lowers the combustion temperature and decreases the amount of nitrous oxide. Although this method has been used in pick-up diesel engines since the 1990s, in its current form it doesn’t meet the new regulations and manufacturers are no longer using this method alone.
Engineers have found a way, however, to combine EGR with rare earth metals like rhodium or palladium, which help to form a trap for nitrous oxide before it’s emitted into the environment. Chrysler is the only manufacturer using this approach and only in their Dodge Ram 2500 and 3500 trucks.
Other manufacturers are choosing a new technology called SCR – selective catalytic reduction. By injecting Diesel Exhaust Fluid (DEF), which contains the organic compound urea, into the hot exhaust, nitrous oxide is broken down into harmless nitrogen gas and water vapor. This requires drivers to add DEF into a separate tank in their vehicles.
Most manufacturers are using the SCR method, including GM and Chrysler in the Dodge Ram 3500, 4500 and 5500 commercial Chassis Cabs. Ford’s new 6.7-liter Power Stroke V-8 diesel engine for the 2011 F-Series Super Duty line will employ a hybrid of EGR and SCR to meet the standard. The balance of the Ford line will use SCR technology alone.
Foreign pick-up manufacturers have been reluctant to jump into the diesel fray in the U.S., mostly because of emissions regulations. Toyota is still promising a diesel Tundra, which was due to be released in 2010 and a diesel Nissan Titan is reportedly still in development.
Manufacturers have made every effort to make the transition a smooth process, creating audio and visual indicators so the driver knows when the DEF tank is running low. It’s critical that the DEF be kept at the required level so the vehicle drives normally. Compliance requirements mean that your truck may not go above 5 mph or even start if the levels aren’t met.
Tank sizes for the DEF range from three gallons on the 2011 GMC Sierra Heavy Duty, which GMC estimates will last around 6,000 miles to Ford’s pick-up line, which will hold between five and seven gallons depending on the model.
DEF should soon be readily available in pumps at truck stops, as well as from auto parts stores, but industry experts advise drivers to carry extra DEF on board to allow time for the supply chain to be established. The cost of DEF will be comparable to the cost of diesel fuel.
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