Fleet Services Education

Understanding Diesel Emission Systems 

Another potential issue with warranty compliance involves the diesel emissions system, such as diesel particulate filters (DPFs), selective catalytic reduction (SCR) systems, and diesel exhaust fluid (DEF). Full regeneration (burning off of soot) of the DPF in urban applications is difficult, when there may be as many as 30 to 40 stops per day. 

If a driver doesn’t accelerate a truck to highway speed long enough to allow for a full regeneration cycle, eventually, the DPF filter will clog. 

Any system that directly interfaces with the engine (such as fuel, cooling, and exhaust) is strongly impacted by high engine hours. For instance, a truck in a high-idling fleet application is less likely to generate temperatures high enough to perform optimal regenerations for the diesel oxidation catalyst. 

During long periods of idling, the operating temperature is lower than a typical duty cycle, requiring the need for more manual regeneration. 

The increased costs related to new emissions technologies have leveled off as fleets and drivers have become more familiar with the trucks. Still, there is a constant stream of new drivers entering the workforce who may not be as familiar as you would like with diesel emissions requirements. 

Drivers are increasingly more responsible for proper maintenance protocols. It’s important for drivers to understand the trucks they’re operating. When it comes to filling the DEF tank, even today some drivers put the wrong product in the wrong tank, creating a potential warranty issue that requires a fleet to back clean the system. To avoid needless warranty issues, it is critical to ensure proper driver compliance with maintenance responsibilities when operating a unit.

Understanding Engine Idling Effects

Excessive engine idling doesn’t just consume fuel; it also creates engine hours, which depending on the OEM (Original Equipment Manufacturer), are used to determine when the powertrain warranty expires. 

Certain fleet applications require a vehicle to idle for long periods to operate auxiliary equipment using a power take-off, which doesn’t create odometer mileage since the vehicle is stationary.

One hour of idling is equal to 25 to 30 miles of driving. High engine hours in low-mileage vehicles can create potential issues that void warranty compliance. Some fleets don’t realize this and are surprised when they are denied coverage, thinking the vehicle is within the warranty mileage parameters or has followed the manufacturer’s recommended maintenance schedule. 

Excessive engine idling has multiple negative effects: 

  1. Hour usage creates wear-and-tear on the engine, decreasing engine life, requiring more frequent PM intervals to stay in warranty compliance. 
  2. Decreases Fuel Economy using more fuel. 
  3. Increased oil consumption. 
  4. Compromises injector tips, turbochargers, and valve seats (Diesel Engines). 
  5. Idling for 10 minutes a day uses more than 27 gallons of fuel a year. 

EXAMPLE: 27 gals @ $2.75 per gallon, multiplied by 300 vehicles = $22,275.00 per year in fuel cost. 

Be mindful of unnecessary engine idling, if it is not necessary to have the vehicle running for auxiliary equipment. Turn the engine off. Understand what vehicles you have that may have high engine hours and know when your Preventative Maintenance check in with fleet should be.