trucks: The Hidden Costs Of Idling

October 1, 1997

3 Min Read
trucks: The Hidden Costs Of Idling

Bob Deierleine

Engine idling not only wastes fuel, but also can destroy components such as engines, alternators, fan clutches, thermostats, water pumps and belts. While an exact cost for excessive idling is tough to quantify, the ramifications are obvious:

* lower fuel economy;

* reduction in oil drain intervals;

* potential injector carboning;

* engine wear; and

* lower battery life.

In 1993, The Maintenance Council, Alexandria, Va., determined that long-haul tractor idling costs an average of $4.66 daily ($3.75 for fuel, 71Cents for preventative maintenance and 20Cents on engine wear), based on the results of a two-year study by fleets and engine manufacturers.

Also, a U.S. Department of Energy (DOE), Washington, D.C., study revealed that the average Class 8 diesel tractor uses 264 gallons of fuel annually while it idles just during a lunch period.

The maintenance costs associated with idling are more difficult to calculate. Estimates from a variety of sources including engine manufacturers, fleet operators and DOE studies have produced these hourly cost estimates:

* $2 for diesel, normally aspirated engines;

* $2.20 for diesel, turbocharged engines; and

* $2.30 for gasoline engines.

Electronic engines' reporting capabilities can be handy tools in managing idling, notes Bob Wessels, a customer support manager for Caterpillar, Peoria, Ill. "Information, including idle and power takeoff (PTO) idle time is downloaded to a computer with equipment management software," he explains.

"We closely track idling time on all power units," says Sam Cross, director of maintenance for Condor Freight Lines, Goshen, Calif. "With electronic engines, it's easy, but on the mechanical engines, the drivers have to track and estimate it."

At Condor, idling is managed by measuring duration, providing driver education, establishing ground rules and rewarding performance. "Our company rules are: No unattended truck is to be left idling and only shop personnel are authorized to change idle shut-off times on electronic engines," Cross explains.

The Condor drivers suggested that the electronic engine idle shut-off mechanism, initially programmed for five minutes, to be reprogrammed for three- and one-half minutes. Since reducing idling time, the fleet has experienced the following results:

* fuel economy is up 0.2 miles per gallon (mpg);

* idling times were reduced 36 percent;

* fuel economy has increased 0.1 mpg; and

* annual fuel saving reached $20,000.

However, James L. Cade, director of maintenance for Ryder System, Miami, warns that poor fuel economy might be affected by factors other than idling, such as mechanical problems, wrong specifications, vehicle usage and bad driver habits. He suggests identifying the real cause for poor fuel economy before fingering idling as the sole problem.

While some fleets are taking the more homespun approach of education and monitoring to reduce idling costs, others are going high-tech, using satellite communications. On-board information is useful, but it is labor-intensive to obtain and manage. And although satellites and other communication channels are efficient, they also are expensive.

Phil Stump, fleet manager for Coastal Beverages, Wilmington, N.C., uses an engine feature, called "Pro-Driver" manufactured by Detroit Diesel, Detroit, as a built-in monitoring system. This feature provides an electronic log book and monitors several engine functions, such as the percent of time over the governed speed, how often hard-braking occurs and the amount of fuel burned during idling. "We have the electronic controls set up to shut down the engine after 20 minutes of idling," he says. "It also catches those drivers who restart the engine right after a shutdown."

"Engine idling not only wastes fuel and revenue, it also is a major source of pollution," complains Bill Byrnes, product manager for Phillips and Temro Industries, Eden Prairie, Minn. "Idling engines do not burn fuel as efficiently as when that engine is under load."

When surveying idle-reducing strategies or equipment, you already should know your fuel consumption statistics, engine maintenance, component replacement intervals and oil change intervals in order to evaluate the performance of the chosen device.

Also, separate driving and idling hours. With the electronic diagnostics available on most of today's engines, it is possible to determine road hours from idle hours.

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