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Below is a breakdown of the ten most frequent semi-truck repairs, how they affect performance, and the best ways to prevent them.
1. Engine Overhauls
The diesel engine is one of the most commonly serviced systems. Symptoms like white smoke, poor fuel economy, or knocking sounds can all indicate internal wear. Often caused by lack of maintenance, fuel contamination, or overheating, engine repairs range from gasket replacements to full overhauls.
Preventive maintenance: Regular oil changes and monitoring engine coolant levels is essential to mitigate long-term wear.
2. Transmission Failures
Semi-truck transmissions—whether manual, automated manual, or automatic—are responsible for optimizing engine power. Frequent shifting under load and poor fluid conditions can lead to gear slippage, grinding, or total transmission failure.
Routine checks of transmission fluid and the clutch system (for manual models) are critical. Overheating or late gear changes are red flags that should never be ignored.
3. Brake System Repairs
Given the weight they carry, semi-trucks rely on air brake systems to stop safely. Brake issues can stem from worn brake shoes, S-cam malfunctions, or air compressor failures. If drivers hear screeching or feel a delay in braking response, they may be dealing with contaminated or failing brake components.
Routinely inspect:
- Air tanks
- Slack adjusters
- Brake drums
4. Tire Blowouts
Tires are one of the most abused components on any semi-truck. Long hauls, under-inflation, or alignment issues all increase the risk of tire blowouts. Aside from obvious safety concerns, a blowout can lead to wheel end damage or even accidents.
For every pre-trip inspection, make sure to go over:
- Regular tire rotations
- Pressure checks
- Proper alignment
5. Cooling System Malfunctions
The cooling system ensures that heat from the engine is properly dissipated. Leaking radiators, faulty water pumps, or malfunctioning fan clutches can all lead to engine overheating.
Checking coolant levels and inspecting hoses and belts for wear helps extend engine life and avoid costly road calls.
6. Electrical Failures
Modern rigs are filled with sensors and circuits, making them vulnerable to electrical failures. Corroded wiring, dead batteries, or alternator malfunctions can shut down essential systems like lighting, ignition, and ECM modules.
Routine checks:
- Battery terminals
- Grounding straps
- Alternator
7. Suspension System Wear
Over time, leaf springs, airbags, and shock absorbers take a beating—especially on poor road surfaces. Drivers may feel excessive bouncing, pulling, or even misalignment during braking. Regular inspections for cracked or sagging components in the suspension system will ensure safe handling and even weight distribution.
8. DPF and EGR Issues
Modern emissions systems, particularly the Diesel Particulate Filter (DPF) and Exhaust Gas Recirculation (EGR) valve, are frequent culprits of reduced performance. DPF clogging and EGR cooler leaks can trigger engine derates and lead to increased fuel usage.
Regular regeneration cycles, sensor diagnostics, and cleaning schedules are key to staying compliant with emissions regulations while maintaining performance.
9. Fuel System Problems
Fuel system issues such as injector failures, fuel pump breakdowns, and filter clogs can lead to stalling, power loss, or hard starts. Contaminated diesel is often the root cause.
Routinely check:
- Replacing filters
- Fuel pressure
- Maintaining clean fuel tanks
10. Wheel Bearing Failures
Wheel bearings reduce friction between the wheel and axle. If they fail, the consequences can be catastrophic—wheels may overheat, seize up, or even detach. Screeching noises, smoking hubs, and excessive play at the wheel end are all warning signs.
Things to routinely consider:
- Regular greasing
- Temperature checks during inspections
- Monitoring for vibration
Stay Road-Ready
From powertrain issues to emissions system failures, semi-trucks are complex machines that demand constant attention. Preventive maintenance isn’t just good practice—it’s vital to safe and efficient trucking.
If your fleet is experiencing recurring issues in Chicago, IL, book an inspection with Connect Truck Center today.
