Manager: Jim Caudill

Title: Maintenance manager

Fleet: AJP Corp., Goshen, IN

Operation: Private bulk carrier


The high price of diesel fuel is exacting an inordinately heavy toll on small fleets, especially if they have the high idling requirements of an operation like AJP Corp.

“Our drivers pull large vacuum pneumatic trailers that carry plastic pellets and [have to] idle their tractor engines almost 45% of the day since they need to operate a PTO when loading,” says Jim Caudill, maintenance manager for the private fleet arm of plastics producer Brunk Corp.

In addition to the vacuum pneumatic trailers, the fleet's 22 tractors pull dry vans, hauling everything from plastic pellets and calcium chloride for snow removal or dust- suppression work to paper and lumber products.

Routes vary tremendously, from 200-mi./day pickup-and-delivery runs to 2,500-mi./week longhaul runs. And since AJP's trade cycle is about eight to ten years, good fuel economy over the life of the vehicle is especially important.

“Saving every penny we can is our motto,” says Caudill. “We'll do anything we can to improve fuel economy.”


An article about a truck- stop chain that heated fuel before it was delivered — resulting in complaints from drivers about vehicle performance — led technicians at AJP to think about the impact of temperature on fuel economy. They realized that both outside air temperature and the engine-fuel return could transfer heat to the tank.

By monitoring fuel tank temperatures, “we learned that as fuel gets warmer, its efficiency drops; as it cools down, fuel economy improves,” says Caudill. “We found that our fuel temperatures reached 110°F to 140°F. in the summer. Since optimum temperature is around 70°F, we thought we could really see some fuel economy benefits if we could cool our fuel down,” he adds.

The fleet tried a variety of aftermarket fuel cooling systems, but was disappointed with the results. Since most of them used coolant to lower fuel temperature as it comes off the engine, AJP decided to develop a system that cooled the fuel as it left the tank.

Their method uses “separate radiant coolers to radiate the heat off” and also forces air through the cooler, “to get an even greater temperature drop,” Caudill explains.

Bingo. The new system yielded a 10%-15% improvement in fuel economy. “Improving fuel efficiency by 10% across-the-board for our fleet is a big deal, since we ran over one-million miles last year,” Caudill points out. “[The system] also adds negligible weight to our trucks, so we're not losing anything by [using it].”

The fuel-cooling system works equally well on old and new systems, which is especially important for a fleet with a trade-cycle like AJP's. “Our older trucks get just as good fuel mileage as the newer ones, ranging between 5.8 mpg into the lower 6's. That's a huge benefit to us and we hope to improve it even further.”

Maintenance Bay presents case studies detailing how fleets resolve maintenance-related issues.