As the temperatures drop and days get shorter, diesel vehicle owners have a few extra tasks to consider. Diesel engines are durable and efficient, but they react differently to cold weather than gasoline engines. If you're heading into fall without a maintenance plan, you may be risking hard starts, reduced fuel economy, or unexpected downtime.
Here are five important maintenance steps to help keep your diesel car or truck running strong through the colder months.
1. Inspect and Replace Fuel Filters
Fuel filters play a crucial role in diesel performance. Diesel fuel naturally contains more impurities than gasoline, and over time, those contaminants build up in the fuel filter. During colder months, water and debris trapped in the filter can freeze, slowing the flow of fuel and leading to hard starts or rough idling.
If you haven’t replaced the fuel filter recently, fall is a good time to do it. Some diesel vehicles have both a primary and secondary fuel filter, so be sure both are checked or replaced if needed. Replacing a clogged filter can restore proper fuel pressure and improve cold-weather performance.
2. Use a Cold-Weather Diesel Fuel Additive
Diesel fuel can gel in low temperatures, especially when untreated. This happens when paraffin wax in the fuel starts to solidify, restricting flow to the engine. Once fuel lines or filters are clogged with gelled diesel, your vehicle might not start at all.
A quality fuel additive can prevent this by lowering the gel point and helping to disperse water. Many additives also improve cetane levels, which supports cleaner combustion and smoother startups. It’s a small investment that protects your engine when temperatures drop unexpectedly.
3. Check Glow Plugs and Their Control System
Unlike gas engines, diesel engines rely on compression and heat to ignite fuel. In cold weather, glow plugs help preheat the combustion chamber to get the engine running. If just one glow plug is faulty, it could lead to long cranks or complete failure to start, especially in freezing conditions.
Fall is the ideal time to test the glow plugs and the glow plug relay or control module. If your diesel vehicle has been cranking slower than usual or producing white smoke at startup, a faulty glow plug may be the cause.
4. Test the Battery and Charging System
Cold temperatures take a toll on battery performance. Diesel engines require more power to crank than gasoline engines, and if your battery is already aging or weak, it might not have enough juice to turn the engine over when it's cold out.
Have the battery tested for voltage and cold cranking amps. If it's nearing the end of its lifespan, replacing it before winter could save you from being stranded. Also make sure the alternator is charging properly and that battery terminals are clean and corrosion-free.
5. Inspect the Cooling System and Heater
Diesel engines operate at higher compression and produce more heat, so the cooling system plays a critical role. As fall begins, make sure the coolant is at the right mixture and in good condition. Old or improperly mixed coolant can freeze in low temperatures or cause internal corrosion.
Also, check the radiator, hoses, and the thermostat. Look for cracks or signs of wear in rubber parts. While you're at it, confirm that the heater and defroster are working well. On cold mornings, you’ll need both for comfort and safety.
Bonus Tip: Keep Emergency Supplies in the Vehicle
No one plans to break down, but if it happens on a cold evening, having basic supplies can make a big difference. Consider keeping these in your diesel vehicle during the colder months:
- Warm blanket or extra coat
- Gloves and flashlight
- Fuel treatment or anti-gel additive
- Jump starter or booster cables
- Phone charger
Even a well-maintained vehicle can face unexpected issues, and being prepared helps reduce stress if you get stuck waiting for help.
Trust Your Diesel Vehicle to J & F Motors Ltd in Arlington, VA
At J & F Motors Ltd in Arlington, VA, our technicians understand what diesel vehicles need to thrive during the fall and winter months. Whether it's replacing fuel filters, inspecting glow plugs, or preparing your fuel system for cold weather, we’re here to help you avoid downtime and keep your diesel running smoothly.
Schedule your seasonal maintenance with our team today and drive into fall with confidence.