5 Overlooked Preventive Maintenance Items That Could Cause Breakdowns
Preventive maintenance isn’t just about oil changes and brake pads. Overlooking small parts like slack adjusters, coolant flow, wheel bearings, air dryers, and fuel water separators can lead to big failures. Stay proactive to avoid breakdowns and costly roadside delays.
When it comes to keeping your heavy-duty truck rolling down the road and not stranded on the side of it, preventive maintenance is non-negotiable. Most drivers stay on top of the big-ticket items—engine oil, tire tread, brake pad thickness—but it’s the smaller components that often cause the biggest headaches.
We asked our team about 5 overlooked preventive maintenance items that could bring your rig to a grinding halt if ignored.
1. Slack Adjusters
Slack adjusters are responsible for keeping the brake stroke within a safe operating range by compensating for brake shoe wear.
When they’re not adjusted properly—or worse, completely seized—you’ll experience delayed braking or, in worst cases, total brake failure. This creates incredibly unsafe conditions on the road.
Tip: During routine checks, manually test your slack adjusters for proper movement and free play. If you notice uneven adjustment or hear unusual grinding, it’s time to get them looked at.
2. Coolant Quality and Flow
Everyone knows you need coolant, but not everyone keeps tabs on coolant quality or flow rate. Over time, coolant breaks down and loses its ability to absorb radiant heat. Worse yet, corroded coolant lines or a failing water pump can block flow, leading to overheating, even in those freezing Alberta winters.
Let it slide too long, and you’re looking at cracked cylinder heads, blown gaskets, or warped engine blocks. None of those are fun... or cheap.
Tip: Test coolant for pH, contaminants, and concentration. Look for scale buildup around the radiator and water pump housing, and ensure your fan clutch is activating at low speeds.
3. Wheel Bearings and Races
Wheel bearings aren't flashy, but they literally keep you rolling. These components reduce friction between the wheel and the axle, allowing for smooth rotation. But when they're dry, contaminated, or worn out, they can overheat, seize, and even cause a wheel-off incident.
Once you hear that high-pitched screech or see smoke coming off your wheel end, it’s already too late.
Tip: Include wheel-end inspections in your PM schedule. Grease your bearings regularly and look for signs of overheating like discolouration, burnt smell, or grease leaks.
4. Air Dryer Maintenance
Edmonton winters don’t mess around, and neither should you when it comes to your air dryer. Its job is to remove moisture from your compressed air system, and if it fails, water can collect in your air lines and brake valves. When the temperature drops, that water freezes, and boom—no brakes.
Even in warmer seasons, a saturated air dryer can corrode internal brake components, leading to system failure and costly downtime.
Tip: Replace the air dryer filter annually and inspect for oil contamination from the air compressor. If your purge valve is leaking or cycling excessively, that’s a red flag.
5. Fuel Water Separator
Your fuel water separator might seem like a “set it and forget it” component, but diesel fuel systems are vulnerable to moisture—especially in humid or wet climates. Water in your fuel leads to poor combustion, injector damage, and even microbial growth (a.k.a. diesel algae). None of that is good for uptime.
Letting that separator go too long without draining or replacing can clog your fuel filter, strain your fuel pump, and trigger hard starts or engine stalls.
Tip: Drain your separator regularly (daily in wet or humid conditions), and don’t ignore dashboard fuel filter warnings. If you notice power loss or sputtering, check it first.
Final Thoughts
These five often-forgotten components may seem minor, but they can deliver major problems if left unchecked. Whether you’re hauling across Alberta or running regional routes around Edmonton, staying ahead of the curve with smart preventive maintenance can mean the difference between on-time delivery and expensive roadside repairs.
Want to keep your rig running like a well-oiled machine? Don’t ignore the little stuff. Next time you schedule a maintenance check, make sure these five items are on the list. Better yet, start a preventive maintenance log to track them before they cause chaos.
Stay proactive. Stay rolling. Stay ahead.