You don't have to go far to find a fleet having trouble with engines, spelling opportunities for aftermarket parts and service.

In its 2012 U.S. Heavy-Duty Truck Engine and Transmission Study, J.D. Power and Associates found 46% of owners of one-model-year-old engines experienced some type of engine-related problem, up from 42% in 2011.

The most commonly reported engine problems were with the electronic control module calibration (23% of owners), exhaust gas recirculation valves (20%), and electronic engine sensors (16%). Those would be mission-critical components in many cases.

Owners of medium-duty truck engines report similar problems, according to J.D. Power's 2012 U.S. Medium-Duty Truck Engine and Transmission Study.

That study found the number of engine and fuel problems fell to 40 problems per 100 trucks (PP100), down by 11 PP100 from 2011. However, the average length of unscheduled downtime due to these problems is 13.4 days, up 2.7 days from 2011.

"The new, more complex engines designed to meet EPA regulations are resulting in additional problems and downtime, which also has a financial impact on owners because they're not making money when their truck is down for service," noted Brent Gruber, director of the commercial vehicle practice at J.D. Power.

Paul Wion, corporate fleet supervisor at Lewis Tree Service in upstate New York, agrees that downtime is a problem. "EGR valves have been troublesome, especially on trucks that don't get a lot of road time."

"Cummins has come up with an updated EGR valve that seems to be more robust," he says. "The valve is pretty easy to change, a couple of bolts and an electrical connection. On the ISB you open the hood and it's staring you in the face."

"But under warranty you typically have four or five days of downtime while you're waiting in line at the dealer, and that's more expensive than the component, which is less than $200. If service providers have the diagnostic tool to determine the problem, we'll let them do it" and not worry about a warranty claim.

There's really no maintenance schedule for most of these problems, whether it's EGR valves, sensors or electronic control modules.

"Today the sensors are better quality, but there are so many more of them on an engine," says Clint O'Neill, a Detroit Diesel certified product trainer at Pacific Power Products in Ridgefield, Wash.

"An EPA '98 engine, for example, had maybe four sensors on the entire engine. Compare that to a 2010 engine with on-board diagnostics. Now there are sensors monitoring sensors. There are 20 or 30 different sensors on an engine today, so your failure rate is going to be higher just based on the numbers."

Not all engine problems stem from new emissions-related issues.

John Wensel, president of Wensel's Truck & Trailer Repair in Spring City, Pa., has noticed an increase in boilerplate parts failing. He sees those failures at the end of a tow hook.

"The top five reasons I get road-call service requests include failed belts and tensioners as well as brake chambers and air compressors," he says. "It's easy to see why a lot of that stuff fails; it's just old and worn out. Somebody isn't doing the regular visual inspections, or they aren't very good at the job."

Wensel suggests there may be another reason for the failure of routine maintenance: budgets.

"I think the economy is forcing some fleets to scrimp on maintenance or unwisely extend their PMs. Others are trying to cut repair costs by fixing only some of the problems."

Wensel recalls one customer with injector problems. His technicians replaced the one injector they knew to be bad, but the truck came back two weeks later with another one.

"The truck was eight years old, and still had the original injectors," says Wensel. "We advised him to replace the others while we had the engine apart, but he opted to push his luck. Then he had the nerve to ask why I charged him full labor time on the second job."

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