- assistant;
- multimeter (in voltmeter mode with a measurement limit of 15-20 V);
- technical stethoscope.
Execution sequence
1. We prepare the car for work (see "Preparing the car for maintenance and repair").
2. We warm up the engine to operating temperature (not less than 80°С).
3. We turn on all the powerful consumers of the car's electricity (heated rear window, electric heater fan, high beam headlights, heated seats).
Comment. We carry out the rest of the work with an assistant.
4. Pressing the pedal "gas" and controlling the operation of the engine using a tachometer, we keep the engine crankshaft speed within 3000-3500 rpm.
5. We measure the voltage at the battery terminals with a voltmeter. With a working generator, the voltmeter should show a voltage of at least 13 V.
Comment. If the voltage is less than 13 V, the alternator drive belt may be loose, a malfunction in the alternator circuit, the alternator voltage regulator is faulty, the brushes in the alternator are oiled or worn out, and other malfunctions in the alternator itself
6. We turn off all consumers of electricity, while the voltmeter should show a voltage not higher than 14.7 V.
Comment. If the voltage is greater than 14.7 V, the voltage regulator is most likely defective.
7. With a stethoscope, we evaluate the condition of the generator bearings by noise. A loud hum indicates wear on one or both bearings (most often the front bearing fails).