Article

Maintaining Diesels

November 2012, TruckingInfo.com - Cover Story

by Jim Park, Equipment Editor & Tom Berg, Senior Editor

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You don't have to go far to find a fleet having trouble with engines. Mostly they report emissions systems problems, not surprising given the short time the engine makers had to meet the Environmental Protection Agency's tight timelines. To be fair, owners of diesels meeting EPA 2010 standards are reporting fewer problems than they had with the first few generations of EPA 2007-compliant engines.



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.

As annoying as such problems are, there's little you can do to prevent them. EGR valves are not maintenance items. There's no replacement schedule. There's also really no maintenance schedule for the other customer complaints noted by J.D. Power sensors and ECMs.

"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."

There is an upside to the newer engines, O'Neill says. Maintenance intervals have been pushed way out from where they were 10 years ago.

"Maintenance schedules for our DD-series engines are now at 50,000 miles for oils and filters," he says. "Those intervals used to be 15,000 miles to 20,000 miles. Sure, the CJ-4 oils are a little more expensive, and they use canister-style modular filters which cost more than screw-on filters, but annual service-related downtime is pretty well halved."

Budget-based maintenance

Unfortunately, other components and systems don't fail in sync with the engine service intervals.

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."

The importance of diagnostics

Not all engine problems are mechanical ones such as failed EGR valves and coolers. Many of the new challenges stem from electrical or electronic demons.

Some problems can't be diagnosed or repaired without expensive and often proprietary equipment. Fault codes hold clues to potential problems, but blinking lights just don't go deep enough in system troubleshooting.

"Back when I was a kid on the floor diagnosing a run-ability complaint, it was a matter of putting your hand on the exhaust manifold and cracking a few injector lines," says O'Neill, wistfully. "Those days are long gone. If you don't have the diagnostic software for your engine, you're working in the dark. Unfortunately, that means they need some sophisticated diagnostic tools as well as the training to use them. That makes things especially difficult for small fleets and owner-operators."

O'Neill says fleets can buy all the hardware and software they need from the OE, but the trouble in many cases is getting the technicians trained to use it to its full capability.

Chris Damiano, director of maintenance at Diesel Direct, a fuel delivery service headquartered in Stoughton, Mass., has had his share of trials and tribulations in dealing with diesels of recent vintage.

"Aftertreatment systems aren't the problem," he says. "It's the surrounding systems that fail. The aftertreatment needs input to work, and when it doesn't get input, it doesn't work."

On his trucks, the engine won't initiate a regen if the check-engine light is on.

"If you ignore it, you pay the price," he says.

The check engine light comes on from some malfunction, such as coolant level, excessive turbo speed, clogged EGR valve, cooler leaking, or clogged differential pressure sensor, which is usually a sign of internal failure of the EGR cooler.

"It doesn't want to self-destruct, so it protects itself," he says. "Our drivers are instructed to tell their bosses or shop people if that warning light is illuminated so whatever's causing it can be found and fixed. If not, the DPF will plug up and the engine will stop running."

Accurate diagnostics and troubleshooting are a must.

"Our technicians plug their laptops into engine controls, note the fault codes which are usually accurate properly follow prescribed troubleshooting steps and then fix the problem," says Damiano. "Sometimes it's a component and sometimes it's a failed sensor. I've replaced thousands of coolant-level sensors."

Hedging your bets

Want some good advice? Be proactive about repairs.

"Keep in close contact, very close contact, with the OEM because there's constant improvement and recalibrations of the engine controls. You have to know about these," suggests Damiano. "Also, keep in touch with outside vendors who work on your trucks when they're not close to a dealer. Keep in touch by phone, e-mail, whatever it takes. Sometimes you have to talk him through a fix."

Pacific Power's O'Neill agrees.

"It really helps to be focused and involved with the repair process while the vehicle is under warranty," he says. "You can learn a lot by watching, listening and asking questions the first time something is repaired. Eventually it will fall out of warranty, and the burden to make the repair will be on the owner. You'll be way ahead buying a code reader and [learning to] understand the fault codes."

Wion says drivers also have to be involved in the process and taught their obligations and responsibilities regarding the emissions systems.

"Part of pre-trip inspections for drivers is to look for warning lights, and follow up on them," he says.

Just so you won't be lulled into comfort thinking a code reader will solve all your problems, Wensel warns that U.S. Department of Transportation inspectors seem to be writing up more trucks for oil leaks and excess grease and contamination on the frame and undercarriage.

"Don't overlook the everyday stuff, and don't neglect parts you might think are almost bulletproof. Sooner or later they will let you down.


Medium-duty and vocational regen cycles

Diesel particulate filters like heat Unfortunately, many medium-duty and vocational diesels don't run hot, or hot enough for very long. This has led to customer complaints about too many active regeneration cycles disrupting daily vehicle operations.

Drivers tend to ignore the regen imperative, especially when they are trained to recognize what the light means, says John Wensel of Wensel's Truck & Trailer Repair in Spring City, Pa. We had a truck in here a while back with a ruined DPF. The driver had bypassed the regen request more than a dozen times before it plugged up solid.

Wensel says drivers on busy schedules feel they don't have the time to spend 20 to 30 minutes parked at high idle every day.
Paul Wion of LewisTree Service in upstate New York, has some 2007 and later Ford F-750s with Caterpillar C7 engines whose DPFs would regenerate to burn off soot only when electronic controls told them to.This was okay in vehicles that saw a lot of highway time, but not at Lewis, whose trucks sat still while their engines drove PTO pumps that ran hydraulic man buckets.

We got into an ice storm here in New York, and basically the trucks would run for 16 hours and then quit because the DPFs would plug, he says.

Wion said that with the help of people at Midway Ford in Kansas City, Mo., the factory agreed to install switches on the dashboards. This way drivers could order a manual regen when warning lights came on.

That meant stopping, setting the parking brake and hitting the switch to start the regen. Most engines go into fast idle as extra fuel is sent down exhaust streams to produce heat in the DPFs to burn off the soot. It takes about 30 minutes and burns varying amounts of fuel.

Regens are a painful but necessary fact of post-EPA-2007 life. Drivers need to be trained how to handle the situation, and fleets should be watching for how often the service is performed, Wensel advises. They can ignore the light a couple of times, but it'll catch you up sooner or later.

Air and fuel systems

Sometimes the most basic systems are overlooked because they aren't part of the new technology-driven dynamic. However, the function of more complex - and costly- systems relies on basic systems for support. Take the air system, for example. The compressor/air drier combination hasn't changed, but the 2010 engines use air to drive DEF pumps.

You can't afford a problem with the air system anymore, says Clint O'Neill, a Detroit Diesel certified product trainer at Pacific Power Products in Ridgefield, Wash. The oil and water has to be filtered out of the system, because a huge percentage of the aftertreatment system's problems are actually failures of a primary system like an air drier or compressor.

JohnWensel, president of Wensel's Truck & Trailer Repair in Spring City, Pa., says compressors and air dryers are among his top five reasons for road calls. That would suggest many of them are in sketchy condition at best - so what are they doing to your DEF pumps and automated transmission air systems?

Don't wait for a failure, he suggests. Get on a maintenance schedule that's appropriate for your climate and operating conditions. And also, point out the air tank drains to your drivers. Often they are hidden behind a skirt or fairing, but they still need to be drained regularly.
How many of your drivers have a jug of fuel conditioner on the truck? That could kill your high-pressure common-rail injector system.

We're seeing problems with emulsifiers in fuel, O'Neill says. The old school taught us to use an emulsifier to disperse the water and let it pass through the fuel system and the injectors. With 30,000 psi to 36,000 psi fuel pressure and the incredibly tight tolerances in the fuel pumps, we can't have water getting into the fuel system. That's why most of today's engines use sophisticated water separators. The fuel additives allow the water to pass through the water separators without being separated.

Water can wreck a high-pressure fuel system, he stresses. Do not put emulsifiers in your fuel.

From the November issue of HDT magazine.

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