Equipment World Digital Magazine
Issue link: http://read.dmtmag.com/i/185325
maintenance | by Tom Jackson | TJackson@randallreilly.com Maintenance on Cummins-Westport natural gas engines N atural gas fuel is making big inroads in the transportation and construction industries for a simple reason. It's $1.50 to $2 cheaper per diesel gallon equivalent than traditional diesel fuel. There's a lot to pencil out before you invest in a natural gas driven truck. You have to calculate how much you'll save on fuel and weigh that against the additional cost of the truck (most of which goes into the cost of the fuel storage tanks) and then come up with a reasonable ROI. You should also investigate the maintenance side of things, to make sure you and your shop is ready to work on these trucks. These engines are actually a little less complex than today's emissions compliant diesel engines. But they are different, and that includes maintenance. We talked with Chip House, director of customer support for natural gas products at Cummins-Westport, to find out more about how you deal with these engines in the shop. Lube oils There are significant differences in the combustion byproducts of a diesel engine vs. a natural gas engine, says House. As a result, there is a separate lube oil spec. "It's based around sulfated ash content," House says. "All engines burn some oil so the ash content in the oil is a factor. The higher the ash content Similar to a diesel engine but with spark plugs, the Cummins ISL G engine runs on natural gas fuel. the more susceptible the engine is to ash deposits on the top of pistons, sparkplugs and valves. For our specification, the oil cannot have an ash content higher than 0.6 percent," he says. By contrast diesel engine oils can contain up to 1.85 percent ash. There's no industry-wide American Petroleum Institute spec or label for this oil, House says. It's simply referred to as gas engine oil, or GEO, he says. Natural gas engines produce very little soot, compared to diesel, and natural gas creates other combustion byproducts, so the additive package on the oils is slightly different. Intervals, filters, analysis The oil change intervals on natural gas engines are very close if not the same as comparable diesels, House says. "The ISX 12 G (natural gas burning) is the same as the ISX 12 diesel, 400 hours," House says. "The basic engine is the same. Same block, same EquipmentWorld.com | October 2013 35 EW1013_Maintenance.indd 35 9/24/13 1:54 PM