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Preventative Maintenance

Proper preventative maintenance helps minimize breakdowns, increases vehicle uptime, and ensures safety and regulatory compliance.

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Preventative maintenance for a heavy-duty truck is a set of regular, scheduled service tasks designed to prevent breakdowns, reduce costly repairs, and extend vehicle lifespan. The frequency may vary by manufacturer, truck model, and use case, but the items below are commonly included:

 

1. Engine and Lubrication System

  • Change engine oil and replace oil filter.

  • Inspect and top up all fluid levels (coolant, power steering, windshield washer, brake fluid).

  • Inspect for oil/coolant leaks.

  • Check/replace fuel filters.

    • Frame mounted fuel filter.

    • Fuel Pump in DD15 have 2 fuel filters: Pre-Filter and Final Filter

  • Replace air filter Causes of restricted air filter:

    • Loss of power

    • Increased fuel consumption

    • After treatment failure

    • Less than optimum engine performance

  • Check belts, pulleys, and tensioners for wear or cracks.

  • Air Compressor: Inspect for signs of air, oil or coolant leaks

  • Adjust valves every 150,000 – 200,000 miles – Engine dependent

 

2. Transmission and Drivetrain

  • Check and change transmission fluid (automatic or manual).

  • Inspect clutch operation and adjustment (manual transmission).

  • Inspect and lubricate U-joints.

  • Check for leaks and proper operation in the drivetrain, differential, and transfer case.

 

3. Braking System

  • Inspect brake linings, pads, and drums/rotors for wear.

  • Check air brake system for leaks.

  • Inspect and adjust slack adjusters.

  • Test parking brake and service brake operation.

  • Inspect hoses and connections for wear or leaks.

 

4. Suspension and Steering

  • Inspect shocks, struts, and springs for wear/damage.

  • Check steering linkage and components.

  • Grease steering and suspension components as needed.

  • Inspect tires for tread depth, uneven wear, damage, and correct air pressure.

  • Inspect King Pins (Play greater than .010” requires replacement)

 

5. Electrical System

  • Test battery condition, terminals, and connections.

  • Inspect alternator and starter operation.

  • Test all exterior and interior lights, warning indicators.

  • Inspect and, if necessary, replace fuses and relays.

  • Check wiring harnesses for wear or damage.

 

6. Cooling System

  • Inspect radiator, hoses, clamps, and water pump for leaks.

  • Flush and replace coolant as per manufacturer schedule.

  • Inspect fan belts and fan clutch.

  • Perform pressure test (must be approved by vehicle owner)

 

7. Fuel System

  • Inspect tank, lines, and filters for leaks or damage.

 

8. Exhaust System

  • Check exhaust pipes, mufflers, hangers, and connections for leaks or corrosion.

  • Replace DEF filter every 300,000 miles

 

9. Body and Cab

  • Check windshield wipers and washers.

  • Inspect mirrors, windows, and glass.

  • Check Safety Equipment: Wheel Chokes, Triangles and Fire Extinguisher.

 

11. Documentation

  • Record all inspected and serviced items.

  • Note any items requiring corrective repair outside of preventative scope.

 

Additional Checks

  • Ensure compliance with DOT or relevant regulatory inspection requirements.

  • Follow OEM and fleet-specific maintenance checklists.

  • Carry out a road test for functional checks (if required).

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