Written by the Motorplex Team
Serving Auburn, Spokane and all of Washington State
When temperatures drop in Washington State, diesel fleet managers face a familiar challenge: keeping vehicles running efficiently through freezing conditions. Cold weather affects diesel engines differently from gasoline engines. Without proper preparation, it can lead to fuel gelling, filter clogs, hard starts, and costly downtime.
That’s why preventative fleet maintenance is essential to protecting your diesel fleet, schedule, and your bottom line.
Preventative Fleet Maintenance for Diesel Fleets
At Motorplex, we work with fleet managers to prepare diesel fleets for winter with comprehensive inspections, ongoing preventive maintenance programs, and on-site fleet repair services. Whether your fleet operates locally or across the state, our technicians understand the unique needs of diesel-powered vehicles and how to keep them performing reliably in all conditions.
Preventing Diesel Fuel Gelling
Diesel engines rely on fuel systems that are more sensitive to cold weather. When temperatures fall below freezing, diesel fuel can begin to gel. Gelling can typically happen at about 20 degrees Fahrenheit or lower.
Why does diesel fuel gel? Gelling happens because paraffin wax in the fuel thickens, reducing flow and clogging filters and injectors. Gelling prevents fuel from reaching the engine, leading to hard starts or complete no-start conditions.
Preventing this starts with using high-quality, winter-blended diesel fuel. Many fuel suppliers adjust their blends seasonally, but it’s still a good idea to confirm the cold flow properties of the fuel you’re using. For fleets operating in mountain passes or eastern Washington’s colder climates, additional protection through anti-gel diesel fuel additives may be necessary.
Check Fuel Filters and Water Separators
Fuel filters and water separators are also critical components to check before winter arrives. Water in diesel systems can freeze, causing damage to injectors or fuel lines. Replacing filters and draining water separators before a cold snap reduces the risk of ice-related blockages and ensures consistent fuel delivery.
Motorplex technicians perform detailed multi-point inspections on fuel systems during a seasonal preventative fleet maintenance service. We look for signs of restriction, corrosion, or leaks that could worsen in freezing temperatures.
Keep Things Warm with a Block Heater
Block heaters are another essential tool for diesel fleet reliability. When plugged in overnight, they keep engine coolant and oil at temperatures that allow easier starts and quicker warm-up times. This not only reduces strain on batteries and starters but also improves overall fuel efficiency during winter idling and short trips. For vehicles without existing block heaters, our team can install and test a block heater system tailored to your fleet.
What’s Happening with the DEF?
Diesel Exhaust Fluid (DEF) is another thing to be aware of. DEF begins to freeze at around 12°F, and if tanks or lines aren’t adequately protected, it can expand and cause damage. Most modern trucks have DEF tank heaters, but they should be tested before winter to ensure they work correctly. Keeping DEF storage areas insulated and above freezing is equally important if you want to keep an in-house supply.
Inspect the Charging System
A thorough fleet vehicle winterization service includes battery testing, charging system inspections, and verifying that all electrical connections are clean and secure. A weak battery in a diesel truck is one of the most common causes of roadside breakdowns when temperatures drop. Motorplex offers both in-shop and mobile services to handle these preventative fleet maintenance checks, ensuring that every vehicle in your fleet is winter-ready before it hits the road.
Motorplex Can Help Prepare Your Diesel Fleet for Winter
Investing in professional diesel fleet maintenance before winter can save you money in unplanned downtime and emergency repairs. A truck that won’t start in the cold disrupts schedules, strains drivers, and increases costs. With Motorplex’s experienced technicians and advanced diagnostic tools, your fleet receives the care and precision it needs to perform reliably through Washington’s coldest months.
Read more tips to help prepare your fleet for winter.