Troubleshooting 9 Common Engine Failures: Methods and Expert Tips

The engine cannot be started.

Causes:

1. Motor power is not connected;
2. Open circuit in the winding;
3. Grounding or short circuit between winding phases;
4. Incorrect winding wiring;
5. Burning from engine meltdown;
6. Incorrect wiring of control equipment.

Problems solution:

1. Check the switch, melt and each contact point and the motor output wire head;
2. To repair an open circuit, heat the affected part to the temperature permitted by the insulation grade to soften the paint, take the wire, repair the broken part with wires of the same specification, wrap with insulation, then paint and allow to dry;
3. The same method is used for grounding or shorting parts, but the affected parts are filled with insulation before painting and drying;
4. To correct wiring errors, check the wiring diagram, heat the ends and reconnect according to the correct method, which includes binding, insulation treatment and painting;
5. To resolve a burnout, determine the cause, eliminate the fault, and prepare a new casting according to engine specifications;
6. To correct incorrect wiring of control equipment, simply correct the wiring.

After the engine is pulled into the power supply, the melt is burned.

Causes:

1. Single-phase engine start;
2. Engine overload or stalling;
3. Insufficient cross-sectional area of ​​the casting;
4. Short circuit in the connection line between the power supply and the motor.

Problems solution:

1. Check the contact points of the power line, motor output line, fuse and switch, and repair any broken lines or incorrect connections that are found;
2. Adjust the load to the nominal value and resolve any faults in the towing mechanism;
3. Melting may not protect the motor from overloading. Generally, the melt should be selected using the formula: Rated melt current = starting current / (2 to 3);
4. Check the short circuit point and repair it.

The engine does not start and vibrates after starting.

Causes:

1. Motor blocking or overload;
2. Incomplete power supply connection;
3. Low voltage;
4. Hard grease or too tight mounting on small engines.

Problems solution:

1. Check the equipment and resolve any faults;
2. Replace the blown fuse and tighten the loose terminal screws. Use a multimeter to check for disconnections or incorrect connections on the power line and repair as necessary;
3. If a motor with a delta connection is incorrectly connected as a Y connection, it must be changed back to a delta connection. If the power supply voltage is too low, contact the power supply department for a solution. If the voltage drop on the power line is too large and the voltage is too low, change to a thicker cable;
4. Use appropriate grease to improve assembly quality.

The motor housing is loaded.

Causes:

1. Incorrect connections of the power line and grounding wire;
2. Moisture in the motor winding and serious aging of the insulation;
3. Output line grounding with junction box.

Problems solution:

1. Correct errors;
2. Dry the engine and replace the aged insulation;
3. Wrap or renew insulation on the outlet line and repair the junction box.

It is difficult to start the engine. After adding the rated load, the motor speed is lower than the rated speed.

Causes:

1. Low voltage in the power supply;
2. The delta connection winding is incorrectly connected as a Y connection;
3. Open welding or fracture in the rotor cage;
4. Excessive winding during rewinding.

Problems solution:

1. Use a voltmeter or multimeter to check the motor input voltage and solve the problem;
2. Change the Y connection back to delta connection;
3. After checking, repair any open welds or fractures;
4. Rewind the motor the correct number of turns.

Low insulation resistance

Causes:

1. Moisture in the winding or water damage;
2. Aging of winding insulation.

Problems solution:

1. Heat the winding to dry;
2. After identifying the problem, the winding can be used continuously. Clean, dry and repaint the winding. If the insulation is too old to function safely, it must be replaced.

Abnormal noise during engine operation

Causes:

1. Worn or defective bearings;
2. Iron core of stator and rotor loose;
3. High or unbalanced voltage;
4. Lack of lubricating grease in the bearings;
5. Fan touching the exhaust fan or blockage in the air duct;
6. Irregular air gap causing friction between the stator and rotor.

Problems solution:

1. Repair or replace bearings;
2. Identify the cause of vibration and recompress the iron core for treatment;
3. Measure power supply voltage and solve the causes of high voltage and imbalances;
4. Clean the bearing and fill it with grease until it reaches half to two-thirds of the bearing chamber;
5. Correct the size of the fan and exhaust fan and repair them, clean the ventilation duct;
6. Adjust the air gap to improve assembly quality.

Engine overheating or smoke

Causes:

1. Excessively high supply voltage, leading to saturation of the magnetic flux density of the iron core and an increase in motor temperature;
2. Low supply voltage resulting in a high increase in motor temperature under rated load;
3. Friction between the iron cores of the stator and rotor;
4. Overload or high resistance in production machines causing engine overheating;
5. Frequent engine starts or excessive rotation back and forth;
6. Fan failure or inadequate ventilation.

Problems solution:

1. If the power supply voltage is significantly above the standard, contact the power supply department for a solution;
2. If the problem is caused by excessive voltage drop in the power line, replace it with a thicker power line;
3. If the power supply voltage is too low, contact the power supply department to increase the voltage;
4. Eliminate failures in driving machines and reduce resistance;
5. If the rated current exceeds, reduce the load, replace the motor with one of greater capacity or take measures to extract capacity;
6. Reduce the number of engine starts, forward and reverse rotations or replace the appropriate engine;
7. If necessary, check the fan blade for looseness or damage and repair or replace it.

When the motor runs without load, the current becomes unbalanced and varies greatly

Cause:

1. Unbalanced supply voltage;
2. Winding failure, such as short circuit between turns or reverse connection of a group of coils;
3. Unequal number of turns in the three-phase winding during rewinding.

Problems solution:

1. Measure the power supply voltage and identify the cause;
2. Disassemble the motor, inspect the winding polarity and faults, and correct or eliminate the problems;
3. Rewind the winding.