Fleet Inspections: What You Should Check Every Visit

Engine Systems and Fluids

Your inspection should begin under the hood. Diesel engines operate under immense pressure and heat, so you need to check:

• Engine oil
• Coolant levels
• Diesel exhaust fluid (DEF)

Look for leaks around gaskets, check fluid quality, and verify levels against OEM specs. Inspecting the air filter and fuel system is equally critical. A clogged filter or worn injector can lower performance and increase emissions. Examine the belts and hoses for cracks, wear, or signs of chafing. These soft components are small but can cause serious engine failure if neglected.

Transmission and Driveline Checks

Inspect transmission fluid or gear oil, depending on the type, and assess for leaks or discoloration. A burnt smell or low level may indicate internal wear. Continue your inspection through the driveshafts, U-joints, and differentials. Ensure all differential housings are sealed, the axle shafts are secure, and no excessive play is present in rotating parts. Worn components here can lead to drivetrain imbalance and mechanical failure.

Brake Systems

Braking systems in heavy-duty vehicles rely on air brakes, which must be checked for both function and safety compliance. Begin with checking:

• Air compressor
• Air dryer
• Reservoir tanks
• Airlines (for pressure and moisture integrity)

Each wheel-end should undergo a detailed evaluation.

Make sure to inspect:

• Brake drums
• Shoes
• S-cams
• Slack adjusters
• Pushrods

Verify stroke measurements and look for uneven wear, cracks, or signs of overheating. Don’t overlook return springs—a faulty spring can leave the system partially engaged and generate friction-related damage.

Suspension and Steering

Move on to suspension components. Evaluate leaf springs, airbags, shocks, and spring hangers. These systems support vehicle load and absorb road impact. Check for cracked leaves, uneven ride height, and leaking or rusted shock absorbers.

On the steering side, examine:

• Tie rods
• Drag links
• Kingpins
• Steering gearboxes

Excessive play, fluid seepage, or worn bushings may point to alignment issues or unsafe handling characteristics.

Tire and Wheel Assemblies

Tires are a fleet's first line of contact with the road—and one of the most frequent causes of violations and breakdowns. During inspections, assess tread depth, inflation pressure, and signs of irregular tire wear. Don’t overlook sidewall integrity; bulges or cracks mean the tire’s structure is compromised.

Every wheel-end should be checked for bearing wear, hub seal leaks, and wheel nut torque. Bearings require proper lubrication and inspection for noise or overheating. A failed wheel bearing can cause total wheel loss on the road.

Lighting and Electrical

Verify the operation of headlights, tail lights, marker lamps, and turn signals. Faulty lighting is not only a DOT violation but a hazard to all motorists. Always check the:

• Battery terminals
• Wiring harnesses
• Alternator output

Loose connections or corroded terminals can affect everything from engine ignition to electronic safety systems.

Exhaust and Emission Control

Your fleet is subject to environmental regulations. During inspections, ensure that the DPF, SCR, DEF injector, and EGR valve are intact and operational. Look for soot buildup, fluid crystallization, or warning codes on the onboard diagnostics system.

Also verify that exhaust clamps, heat shields, and mounting brackets are secure. Exhaust leaks can trigger fault codes and introduce fumes into the cab—putting drivers at risk.

Chassis and Frame

Lastly, give the chassis and structural components a once-over. Look for frame cracks, rust spots, or loose crossmembers. Suspension mounts, fifth wheels, and landing gear should be tight and free of damage or deformation.

Also, inspect the fuel tanks, steps, fairings, and battery boxes. Any damage here can compromise structural integrity or pose safety risks.

Documentation and Compliance Review

Before closing the inspection, review the maintenance logs, inspection checklists, and compliance reports. Ensure all findings are documented, and any issues are tagged for immediate correction or monitoring. This paper trail isn't just good practice—it’s your shield during audits and regulatory reviews.

Keep Your Fleet Road-Ready

Need help building a detailed inspection routine or training your team? Reach out to the fleet experts at Kustom Truck & Tire in Des Moines. We can help you create an inspection plan tailored to your fleet’s needs—because keeping your trucks moving starts with knowing what to check.