I. Starting and Operation Issues
Q1: After pressing the start button, the starter motor does not turn. What should I do?
First, check the voltage reading on the control panel. If the voltage is below 10V (for 12V systems) or 20V (for 24V systems), the battery is discharged. Inspect the battery terminals for oxidation or looseness, clean them, and re-tighten. If the voltage is normal, use a screwdriver to short the two large terminals of the starter relay. If the motor turns, the relay is faulty; if it does not turn, the starter motor itself is defective.
Q2: The starter motor turns quickly, but the engine fails to start. What is the cause?
This is typically a fuel system issue. First, check the fuel level in the tank, then verify that the fuel shut-off valve is open. Next, loosen the bleed screw on the injection pump and manually pump fuel until fuel without bubbles is expelled, then tighten the screw. If the engine still fails to start, check the air filter indicator. If the red piston has risen, the filter element is clogged and requires replacement.
Q3: After starting, the engine emits white smoke, which becomes increasingly dense. What is happening?
White smoke usually indicates moisture inside the cylinders. Place your hand near the exhaust pipe outlet. If moisture condenses on your palm, it suggests a blown head gasket or a cracked cylinder block, allowing coolant to enter the combustion chamber. In this case, the engine must be stopped immediately; otherwise, liquid lock may occur, causing connecting rod bending.
Q4: The engine produces a "clicking" sound that accelerates with increasing RPM. Is this serious?
This is a typical sign of excessive valve clearance. With the engine cold, remove the valve cover and use a feeler gauge to check the clearance. Standard specifications are 0.20–0.30 mm for the intake valve and 0.30–0.40 mm for the exhaust valve. If the clearance exceeds specifications, loosen the locknut and adjust to the specified value before re-tightening. This issue is not urgent, but prolonged neglect will accelerate valve wear.
Q5: The engine emits black smoke, and power output is significantly reduced. How can I quickly identify the cause?
First, check the air filter indicator. If it indicates a blockage, replace the filter element; the black smoke should then disappear. If the filter is not blocked, loosen the high-pressure fuel line connections one by one. If the black smoke disappears when a particular cylinder is cut off, this indicates that the injector for that cylinder has poor atomization or excessive fuel delivery, requiring injector inspection.
Q6: The generator produces normal voltage at no load, but voltage drops significantly when a load is applied. How should this be handled?
This is a typical symptom of insufficient excitation system capacity under load. Check the carbon brush length; if it is less than 15 mm, replacement is required. Measure the resistance between the rotor slip rings; it should be between 2 and 6 Ω. Higher resistance indicates poor contact in the excitation winding, while lower resistance indicates an inter-turn short circuit. If the carbon brushes and resistance readings are normal, the automatic voltage regulator (AVR) should be replaced.
Q7: During operation, voltage suddenly disappears, but the engine continues running normally. Where is the fault?
First, check the main circuit breaker and fuses. If they are normal, use a multimeter to measure the input side of the AVR. If input voltage is present but no output, the AVR is burnt out. If there is no input voltage to the AVR, inspect the excitation circuit fuse and the rotating rectifier module. In the field, 80% of such failures are caused by a blown AVR fuse or a failed rotating diode.
Q8: Three-phase voltage is unbalanced, with one phase significantly low, but the engine runs smoothly. What is the problem?
The issue lies in the generator stator winding or connections. First, check the output terminal connections for looseness. If they are secure, de-energize the unit and measure the DC resistance of the three-phase windings with a multimeter. A low reading on one phase indicates an inter-turn short circuit; a high reading indicates poor contact or a broken strand. Professional winding repair is required for this condition.
Q9: During operation, the generator frequency is unstable, fluctuating up and down. What should I check?
Frequency is determined by engine speed, so the issue lies in the governing system. For mechanical governors, check for sticking flyweights or a worn spring. For electronic governors, verify the actuator connection and ensure the speed sensor gap is correct (standard 0.8–1.2 mm).
Q10: Oil pressure is low, but the oil level is normal. What could be the cause?
After starting, observe the pressure gauge. Pressure should be no less than 0.1 MPa at idle and no less than 0.3 MPa at rated speed. If pressure is low, first check whether the oil viscosity is too low (test by dripping oil onto paper and observing the spread pattern). Next, check if the oil filter is clogged (replace it and observe any pressure improvement). If pressure remains low, consider oil pump wear or excessive bearing clearance.
Q11: Coolant level requires topping up weekly, but no external leak can be found. What should I do?
This may indicate an internal leak. After starting, open the radiator cap with caution (danger of hot coolant). If bubbles emerge continuously, the head gasket is blown, allowing combustion gases to enter the cooling system. Alternatively, with the engine cold, remove the glow plugs or injectors and use an endoscope to inspect the piston tops. If one cylinder appears unusually clean, coolant is entering that cylinder.
Q12: The engine is vibrating significantly more than usual. What are possible causes?
First, check whether the mounting bolts are loose. If they are secure, disconnect the coupling and run the engine and generator separately to isolate the vibration source. Excessive engine vibration may indicate a bent crankshaft or imbalanced flywheel; excessive generator vibration may indicate bearing wear or a rotor eccentricity.
Q13: If the generator will not be used for an extended period, what maintenance is required?
Run the generator unloaded for 15–20 minutes each month to ensure oil reaches all lubricated surfaces, and simultaneously charge the battery. Before starting after long-term storage, measure the insulation resistance with a megohmmeter. If it falls below 1 MΩ, drying treatment is required. Before starting, rotate the flywheel manually to confirm no binding, then start the unit.
Q14: Should oil changes be based on time or operating hours?
The change interval is determined by whichever comes first. Mineral oil: every 250 hours or 6 months; semi-synthetic oil: every 350 hours or 9 months; full synthetic oil: every 500 hours or 12 months. For units that have been idle for long periods, oil must still be changed according to the time interval even if the hour count has not been reached, as oil absorbs moisture and emulsifies over time, leading to degradation.
Q15: Can an air filter element be cleaned with compressed air and reused?
This is acceptable as a temporary measure but not recommended as a routine practice. Compressed air blowing damages the paper fiber structure, reducing filtration efficiency. Inspect the element with a light; if any pinholes or light penetration points are visible, it must be replaced. Under normal conditions, replacement should occur every 500 hours; in dusty environments, every 250 hours.
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