How should diesel generators be maintained and serviced

Diesel generators, as the core equipment of backup or main power sources, their maintenance and upkeep are directly related to the equipment's lifespan, operational stability and emergency power supply capacity. The following provides a systematic maintenance plan from five dimensions: daily inspection, regular maintenance, seasonal maintenance, long-term storage management, and fault handling:

I. Daily Inspection and Basic Maintenance

Operation status monitoring

Instrument panel inspection: Before starting every day, observe whether the parameters such as the voltmeter, ammeter, frequency meter, oil pressure meter, and water temperature meter are within the normal range (for example, oil pressure ≥0.3MPa, water temperature ≤95℃).

Abnormal sounds/vibrations: During operation, listen for any unusual sounds from the engine (such as knocking sounds or bearing noises), and touch the engine block to determine if the vibration is abnormal (for industrial-grade units, the vibration value should be ≤7.1mm/s).

Exhaust color: Normal exhaust should be light gray. Black smoke indicates incomplete combustion (check the fuel injector or air filter), and white smoke may be a coolant leak (check the cylinder gasket or water jacket).

Fuel system maintenance

Fuel quality: Use No.0 diesel that meets the GB 252 standard, avoid water content or impurities (water content ≤0.05%), and send the fuel quality for inspection every quarter.

Fuel filter: Replace the paper filter element every 250 hours of operation and clean the sediment at the bottom of the fuel tank every 500 hours.

Daily fuel tank management: Keep the fuel level in the tank between 1/2 and 3/4 to prevent air from entering the fuel line due to the fuel level being too low.

Maintenance of lubrication system

Engine oil selection: Choose the appropriate viscosity based on the ambient temperature (for example, 15W-40 is suitable for an environment ranging from -15℃ to 40℃). Test the engine oil viscosity every 250 hours of operation (the change rate of kinematic viscosity should be ≤25%).

Oil change: Change the oil and filter every 500 hours of operation or once a year (whichever comes first). For industrial-grade units, the time limit can be extended to 1000 hours (fully synthetic oil must be used).

Oil level check: Before starting the engine every day, check the oil level (it should be between the upper and lower marks on the dipstick). A low oil level can cause the engine to pull cylinders.

Ii. Regular deep Maintenance (classified by operating time)

Maintenance is required every 250 hours of operation

Air filter: Clean the paper filter element (blow it from the inside out with compressed air, pressure ≤0.3MPa), and replace it if damaged.

Coolant inspection: Test the freezing point (≤-35℃ in winter) and pH value (7.5 to 9.0). Use coolant of the same brand when replenishing.

Battery maintenance: Check the electrolyte level (10 to 15mm above the plates), measure the specific gravity with a densitometer (1.28±0.01), and charge if the voltage is lower than 12.4V.

Maintenance is required every 500 hours of operation

Diesel filter: Replace the paper filter element and clean the impurities in the filter seat.

Fuel injector calibration: Use an fuel injector detector to test the fuel injection pressure (the standard value varies by model, for example, 25.5MPa for Cummins NT855) and spray quality.

Belt tension adjustment: Use a tensiometer to measure the tension of the generator belt (for example, if a 50N force is applied to the center point of a 12V belt, the deflection should be 10 to 15mm).

Maintenance is required every 1,000 hours of operation

Valve clearance adjustment: Use a feeler gauge to check the intake valve clearance (usually 0.25 to 0.30mm) and the exhaust valve clearance (0.35 to 0.40mm) when the machine is cold.

Turbocharger cleaning: Disassemble the turbocharger rotor, clean the bearings and oil seals with kerosene, and replace the special lubricating oil.

Oil pump inspection: Test the oil pump pressure (≥0.15MPa at idle speed and ≥0.35MPa at rated speed). If the pressure is insufficient, the pump body needs to be replaced.

Iii. Seasonal Specialized Maintenance

Winter maintenance (ambient temperature ≤5℃)

Coolant antifreeze: Replace with -35℃ antifreeze or use a mixture of "50% water +50% ethylene glycol".

Preheating system inspection: Test the intake preheating plug (with a resistance value of 30 to 50Ω) and the coolant preheater (power ≥2kW) to ensure normal low-temperature start-up.

Fuel heating: Install electric heating tapes on daily-use fuel tanks and fuel pipelines to prevent diesel from waxing (the freezing point should be 5 to 7 degrees Celsius lower than the ambient temperature).

Summer maintenance (ambient temperature ≥30℃)

Heat dissipation enhancement: Clean the radiator fins (rinse from the front with a high-pressure water gun, pressure ≤0.5MPa), and remove surface willow catkins and dust.

Coolant circulation: Check the thermostat opening temperature (usually 82 to 88℃). If it gets stuck, replace it.

Ventilation optimization: Ensure that the ventilation area of the machine room is ≥ the heat dissipation of the unit (1kW≈0.3m² ventilation area), and avoid the backflow of hot air.

Maintenance in damp environments

Electrical system moisture-proofing: Fill the control box with moisture-proof agents (such as silicone), and spray three-proof varnish (moisture-proof, mold-proof, and salt spray-proof) on the motor windings.

Anti-corrosion of metal parts: Apply anti-rust paint (such as epoxy zinc-rich primer + polyurethane topcoat) to exposed metal parts of the unit's casing, brackets, etc.

Iv. Long-term Storage Management (Out of use for ≥30 days

Fuel system treatment

Drain the fuel: Completely remove the diesel from the daily-use fuel tank and fuel lines to prevent the sedimentation of gum.

Add stabilizer: If fuel needs to be retained, add diesel stabilizer (such as Stanadyne Performance Formula) at a ratio of 1:1000.

Lubrication system protection

Change long-lasting engine oil: Use fully synthetic engine oil containing anti-corrosion additives (such as Mobil Delvac 1 ESP 5W-40).

Turning operation: Manually turn the machine 1 to 2 times per week to prevent the piston rings from sticking (for automated units, a timed turning program can be set).

Battery maintenance

Disconnection: Remove the negative cable of the battery to prevent self-discharge.

Regular charging: Recharge the battery with the smart charger every two months (charging voltage 14.4V, charging time ≤8 hours).

V. Common Faults and Emergency Handling

Failed startup

Troubleshooting steps

Check the battery voltage (≥12.4V);

Test the starting motor (no-load current ≤200A);

Check if air has entered the fuel line (loosen the air release screw of the high-pressure fuel pump to release air).

Verify whether the preheating system is working properly (preheating for 30 to 60 seconds in winter is required).

Sudden shutdown during operation

Possible causes:

Low oil pressure protection (oil pressure ≤0.15MPa)

Overspeed protection (speed ≥ 115% of the rated speed);

The coolant temperature is too high (≥105℃);

The emergency stop button has been triggered.

Handling measures: Check the alarm information of the instrument, and reset the protection device after eliminating the fault.

The output voltage is unstable

Adjustment method

Check whether the wiring of the AVR(Automatic Voltage Regulator) is loose.

Measure the excitation current with a multimeter (±10% of the rated value);

Adjust the carbon brush pressure (0.15 to 0.25N/cm²) and replace the worn carbon brushes.