MONTREAL, Que. — Don’t let the size of a truck fool you. Medium-duty trucks are dwarfed by their Class 8 counterparts, but such equipment can present some of the biggest challenges for a repair facility.

Chief among them is the fact that many of these trucks are owned and operated by businesses that often treat trucks as an afterthought. The people at the wheel might be bakers, carpenters, electricians or landscapers. They don’t think of themselves as truckers. The trucks are simply seen as a way to deliver tools of the trade.

It’s up to technicians and mechanics to be able to draw out the information they need, even if the customers are not as familiar with truck components.

“The more skilled the technician is and understands our truck, the easier it is for him to work with the customer to diagnose what the issues are. The key thing is really communication,” says Andy Craig, director of Canada operations for Isuzu commercial trucks, stressing the importance of continuous training.

Still, the discussions that lead to accurate diagnostics can be complicated by the fact that many medium-truck users are not dedicated to the trucking business at large. They can struggle to explain how a vehicle feels when they’re behind the wheel.

“Their core business isn’t making deliveries. They purchased something to help get the product there,” says Robbie McLellan, director of service operations at Altruck, a multi-store International dealer headquartered in Guelph, Ont.

The lack of familiarity with the truck can also be the source of trouble, says Fred Lafleur, owner of four Mecamobile multi-brand service shops, operating in the Montreal area under the TruckPro banner.

“It’s common that the medium-duty user doesn’t really know what his truck can and can’t do,” he says, referring to weight capacities that can be stretched to the limit by an occasional excessive payload.

Weight-related truck damage

Extra weight takes a toll on components including the suspension, tires and steering system alike. And those already face unique stresses in the midst of urban routes where potholes and tight turns are part of the daily routine, compounded by regular contact with curbs.

Even a reasonable payload can lead to maintenance challenges if the weight is badly distributed. Think of a plumber who carries all his pipes and fittings on the same side of a cube or panel truck. In a case like that, maintenance teams will need to pay special attention to the suspension and uneven brake wear.

“Brakes would be a big one for sure,” McLellan says, observing how Class 3-7 trucks usually find themselves in a constant stop-and-go environment.

While some medium-duty equipment can come with exhaust brakes to help preserve service brakes, their bark tends to be silenced in the urban areas where these vehicles tend to operate.

Steering systems present another maintenance challenges since many of the front ends in these vehicle classes are non-greaseable, Lafleur adds.

Other components such as wheel bearings can be serviced more easily, but are too often neglected on medium-duty trucks, he says. “These trucks are not built to run 200,000-plus  kilometers without the wheel bearings being disassembled, adjusted, lubricated or replaced if needed. That can be a real problem for a truck driven mostly in urban settings.”

Lack of maintenance awareness

“Awareness of the importance of preventive maintenance is the big issue within the segment,” says Isuzu’s Craig. Thoughts about a truck’s condition often take a back seat to other business demands.

It’s why many medium-duty truck dealers focus on coaching customers about preventive issues – particularly when it comes to the warning lights linked to complex aftertreatment systems. For a non-trucker who ignores the check engine light in their car for weeks on end, just how important is the regen supposed to be?

“You can do it for a couple of hours until you get to a shop, but if you ignore it for a week,” Lafleur says. “You probably have damaged all your DPF system and you get stuck on the side of the road because regens didn’t occur, and everything [in the aftertreatment system ] got clogged.”

Excessive idling tends to be common in many medium-duty applications as well, causing its own harm to the aftertreatment systems. It’s why McLellan thinks technicians should pay particular attention to them. “You create soot, dirt, and things like that internally that you wouldn’t create if you were running down the highway,” he says.

That’s one of the reasons why Isuzu dealers often focus on operating hours rather than mileage when assessing a truck’s health.

“The truck maybe starts up at 8:00 and goes until 6:00 and never shuts off,” Craig says, referring to long idle periods.

Some buyers dodge the need for diesel exhaust fluid by selecting a gasoline-powered model. There are no regens in those. But you still have emissions-related issues to manage, and maintenance needs for components like injectors, Lafleur says.

“Gasoline engines have been using EGR valves forever and still do. They also need to calculate fuel pressure, they have a canister system for gasoline fumes, and they also have a catalyst. It’s not as advanced as on a diesel, but it’s still there.”

Maintaining electrical connections

While electrical malfunctions can be a nightmare to address on any truck, medium-duty models also introduce the added challenge of bodies or vocational equipment that was introduced by a body builder after the truck rolls off the assembly line. If the body wasn’t properly connected to the chassis, there will be wiring issues to address.

Most truck manufacturers have addressed such challenges by adopting plug-in, ready-to-use harnesses rather than requiring splices. “We provide all the body builders with wiring diagrams and information on alterations, what to touch, what not to touch,” Craig says.

“The old style was, you searched through the dash and found a power wire and you found a ground wire and you found the signal wire,” McLellan says. “All manufacturers have done a really good job for the body builders.”

Fighting grime and corrosion

But even the best connections will face attacks from de-icing compounds and the repeated splashes of standing water on city streets. To compound matters, urban driving tends to expose the units to plenty of road dust and airborne particles that might otherwise blow off a Class 8 tractor at highway speeds. It means rads can require regular cleaning to keep the cooling system operating as it should.

Lafleur notes that some pick-up based medium-duty trucks are equipped with as many as seven different radiators that all need to be taken care of. “A tiny leak is enough for oily matter to accumulate on radiators and dust to stick to it, potentially leading to engine overheating issues and premature wear,” he says.

All that dust and road grime can also play a role in shortening the lives of fuel filters, requiring careful attention for the equipment that tends to run at low speeds in heavy city traffic.

Many truck owners adopt rust-proofing treatments as a barrier against the corrosive threats, and Lafleur recommends the work.

“We can see by the floor, lower body panels or radiator supports’ level of corrosion if the owner had it treated. The difference is huge. After 10 years, rust hasn’t eaten away the vehicle,” he says.

Spare parts and know-how

Given their low mileage, it’s not unusual for medium-duty trucks to stay in service for 10-15 years, sometimes more. This means shop managers need to secure access to a particularly wide selection of spare parts, and ensure technicians are trained in equipment with a wide range of model years.

It’s one of the reasons why some shops that service medium-duty trucks like to hire personnel from the car business. “If you’re a truck guy, you may not have worked on hydraulic brakes for the last 10 years. It might have always been on air brakes,” McLellan adds.

In the meantime, they require some of the earliest training on advanced technologies, since the trucks travel distances that are more likely to support alternative fuels or battery-electric operations.

But technicians know that a truck is more than the powertrain. Eliminating the internal combustion engine still leaves plenty of maintenance demands, Lafleur says. There are still the brakes, the suspension, steering and lighting to contend with. That will all need a level of specialized repair.

And that will require savvy truck techs.