Diesel Generator User Guide: Avoid Common Mistakes

As an important backup power device, diesel generators play an indispensable role in many situations. Whether in industrial production, commercial operations, or home emergencies, correct use and maintenance of diesel generators are key to ensuring their efficient operation and prolonging their service life. However, in actual use, many users, due to lack of relevant knowledge or carelessness, often make operational mistakes, leading to frequent equipment failures. This not only affects performance but may also pose safety hazards. This article will detail common operational mistakes with diesel generators and provide correct usage and maintenance suggestions to help users avoid these issues and ensure the equipment remains in good working condition.

Many users, after starting a diesel generator, immediately run it under load without sufficient warm-up. This practice is extremely wrong. When a diesel engine starts cold, due to high oil viscosity and poor fluidity, insufficient oil supply from the oil pump causes the machine's friction surfaces to be poorly lubricated, easily resulting in rapid wear or even severe failures such as cylinder scoring and bearing damage.

Proper Procedure: After a cold start, a diesel engine should first idle for a period to allow the oil temperature to rise gradually. Generally, the equipment should only operate under load once the oil temperature exceeds 40℃. This ensures proper oil flow, provides good lubrication to all friction surfaces, reduces wear, and prolongs the equipment's service life.

Some users fail to develop the habit of regularly checking engine oil, continuing to run the equipment even when oil is low. Insufficient oil leads to inadequate supply to friction surfaces, causing abnormal wear or burn damage, and in severe cases, cylinder scoring or bearing damage.

Proper Procedure: Before using a diesel generator, always check that engine oil is sufficient. During operation, regularly check oil level and quality. If oil is low or degraded, replenish or replace it promptly. Additionally, ensure the oil type meets the equipment's requirements for optimal lubrication.

Many users, after using a diesel generator, shut it off directly without idling to cool down. This causes the cooling system to stop circulating water, sharply reducing heat dissipation, and overheats critical components such as the cylinder head, cylinder sleeve, and cylinder block, which may crack or cause the piston to expand and seize in the sleeve. Moreover, insufficient oil on friction surfaces without cooldown increases wear during the next startup due to poor lubrication.

Proper Procedure: Before shutdown, remove the load first, allow the equipment to gradually reduce speed, and run idle for a few minutes so the components’ temperature decreases slowly. This ensures the cooling system has time to dissipate heat and helps maintain lubrication on friction surfaces, reducing temperature-related wear.

Some users neglect to maintain adequate coolant levels, resulting in reduced cooling efficiency and equipment overheating. Additionally, some use tap or river water as coolant. These waters contain minerals that easily form scale under high temperatures, lowering heat dissipation and aggravating overheating.

Proper Procedure: Ensure sufficient coolant levels and check the system regularly. It is recommended to use specialized coolant instead of ordinary water. Coolants offer better heat transfer, anti-rust, and anti-corrosion properties, effectively prolonging equipment life. For small and large cooling loops, ensure thermostat bypass and outlet valves work properly to prevent scaling-related blockages that compromise cooling.

During operation, excessively high or low coolant temperatures adversely affect the equipment. High coolant temperature subjects the cylinder head, sleeve, piston assembly, and valves to heavy thermal loads, rapidly decreasing mechanical performance, causing component deformation, accelerating wear, and potentially causing cracks or seizure. High coolant or oil temperatures accelerate oil degradation and burning, lowering viscosity, worsening lubrication, and causing abnormal wear.

Low coolant temperature lowers cylinder wall temperature, causing water vapor from combustion to condense and react with exhaust gases to form acidic substances that adhere to cylinder walls, causing corrosion wear. Low cylinder temperatures also extend diesel ignition delay, sharply increasing pressure and causing rough combustion, which can mechanically damage components.

Proper Procedure: The normal operating coolant temperature for a diesel generator is 85℃–95℃. Users should monitor the coolant temperature gauge to ensure it stays in this range. If temperature is too high or low, take corrective measures, such as adjusting fan speed or inspecting the cooling system for faults. Regularly check radiators, pumps, and other cooling components to ensure proper heat dissipation.

Some users do not monitor the oil pressure gauge or indicator light, failing to notice low oil pressure. Low oil pressure prevents normal oil circulation and pressure lubrication, leaving friction surfaces insufficiently lubricated, increasing wear, and shortening service life.

Proper Procedure: During operation, regularly check the oil pressure gauge or indicator. If oil pressure falls below the specified level, stop the engine immediately, resolve the issue, and then restart. Regularly inspect the oil pump, filter, and related components to maintain proper oil pressure and provide adequate lubrication.

Some users push diesel generators to operate under excessive load and high speed to achieve higher power output. However, running a generator at overspeed or overload increases thermal and mechanical stress on cylinder liners, pistons, and connecting rods, making issues like cylinder scuffing or bearing damage more likely. Long-term overload can also cause prolonged harsh combustion inside cylinders, potentially damaging cylinder gaskets.

Proper Operation: Diesel generators should always operate within their rated power and speed limits. Users should match the load to actual electricity needs, ensuring the generator runs within its normal operating range. Regular checks of the generator’s operating condition are recommended to detect and address potential faults early, maintaining stable operation.

Some users abruptly stop the generator while it is running at high speed. This can cause severe inertial damage to the crankshaft, connecting rods, and valve train, reducing the generator’s lifespan. Sudden heavy throttle can also lead to fuel entering the cylinders faster than it can burn, flowing along cylinder walls, diluting the lubricating oil, and causing excessive carbon buildup on pistons, valves, and combustion chambers, potentially clogging fuel injectors or seizing pistons.

Proper Procedure: Before shutdown, first disconnect the load, allow the generator to gradually reduce speed, run briefly under no load for a few minutes, then shut down. This reduces inertial stress on components and helps maintain internal cleanliness, minimizing carbon buildup.

Some users respond to low coolant or overheating by suddenly adding water. This rapid temperature change can cause cracks in the cylinder head, liner, or block, damaging the generator.

Proper Procedure: If overheating occurs, first disconnect the load and slightly increase speed to help lower temperature, then shut down the generator. Loosen the radiator cap to release steam, and if necessary, slowly add coolant to the radiator to avoid thermal shock and prevent damage.

Some users keep diesel generators idling for extended periods to maintain standby status. However, prolonged idling leads to low oil pressure and insufficient piston-top fuel cooling, causing accelerated wear and a higher risk of cylinder scuffing. Idling also results in poor fuel atomization, incomplete combustion, severe carbon buildup, and in some cases, stuck valves or piston rings, and cylinder liner pitting.

Recommended Duration: Diesel generators should be idled for no more than 15–20 minutes. If the equipment is not needed for a long period, it should be shut down promptly to avoid unnecessary wear and carbon accumulation. After starting the generator, it should quickly transition to normal operating speed, minimizing idling time.

Some users shut down diesel generators while still under load. This practice can easily cause demagnetization of brushes in brushed generators and lead to heat dissipation problems, reducing the generator's service life.

Proper Procedure: Before shutdown, first disconnect the load, allow the generator to slow from high speed to low speed, and run for 3–5 minutes before turning off. This effectively prevents brush demagnetization and overheating, ensuring normal operation.

Many users do not follow proper startup and shutdown procedures. For example, starting at high speed without idling or shutting down immediately without cooling can negatively impact the generator and shorten its lifespan.

Correct Procedure: When starting a diesel generator, first allow it to idle until stable, then gradually increase the speed and connect the load after reaching the required operating parameters. During shutdown, disconnect the load first, reduce speed from high to low, run for 3–5 minutes, and then power off. Following correct procedures reduces wear during startup and shutdown, ensuring stable operation.

As an essential standby power source, proper use and maintenance of diesel generators are critical to ensuring efficient operation and long service life. Users should avoid the common mistakes described above and strictly follow the equipment manual. Regularly check key indicators such as oil, coolant, and oil pressure to ensure the generator remains in good condition. Developing good operating habits, adhering to correct startup and shutdown procedures, and maintaining proper maintenance will ensure that the diesel generator performs reliably in all emergency situations, providing consistent power support.