Can I replace an alternator myself?

The usual setup is a diesel engine driving an alternator that supplies electricity to charge the battery and run other electronic accessories, which is a function of the alternator in the gen-set (generator and power-supply system).

 

A "V-belt" from the turbine shaft will go through the alternator and power the generator. Ensure the system has enough oil because the belt will burn through if there isn't. Additionally, look for cracks, breaks, and overheating symptoms in the belt.

How to change a generator's alternator

To change a diesel engine generator's DC alternator, you will need to follow these steps:

1. Shut off the diesel generator and disconnect it from any power source.

2. Locate the DC alternator on the generator. It is typically mounted on the side of the engine near the front.

3. Disconnect the negative battery cable from the battery to prevent any electrical accidents.

4. Remove the bolts or screws that hold the DC alternator in place.

5. Carefully remove the old DC alternator from the engine.

6. Install the new DC alternator in the same position as the old one, using the bolts or screws you removed in step 4.

7. Replace the V-belt and check that it is mounted properly on the alternator shafts and the turbine. There should be between 12 and 15 percent residual stretch in the belt. A belt that has been overstretched may vibrate too much and break before its time. Additionally, ensure no excessive alternator play when the engine is operating. It would indicate that the generator's axis is not perpendicular to the engine's crankshaft and would also lead to belt failure. The mounting bolts may need to be loosened or tightened to adjust the alternator.

8. Reconnect the negative battery cable to the battery.

9. Once the new alternator is in place, give the V-belt a light spray of lubricant, most commonly automotive-bearing grease. Start the engine and check for belt swing or alignment problems between the alternator and the turbine shaft. A slip-joint wrench or a  mechanics hammer may be necessary to adjust the alternator mounting bolts. Your new alternator is ready to recharge the battery and provide electrical power for accessories and cabin lights.

10. Start the diesel generator and test the DC alternator to ensure it works correctly.

It is important to note that this process may vary depending on the specific model of diesel generator you are working with. If unsure about any part of the process, it is always best to consult the manufacturer's instructions or a professional mechanic.

Troubleshooting an alternator

Because there are so many potential problems, troubleshooting the DC alternator on a diesel engine generator can be challenging. Common problems to look for include corroded or loose connections, a bad regulator, a broken exciter, or a bad diode.

The following procedures can be used to troubleshoot a diesel engine generator's DC alternator:

1. First, check the connections to the alternator to ensure that they are tight and free of corrosion. Loose or corroded connections can prevent the alternator from functioning correctly.

2. Next, check the regulator to ensure it is functioning correctly. A faulty regulator can cause the alternator to produce insufficient voltage.

3. If the regulator is functioning correctly, check the exciter to ensure it is also functioning properly. The exciter is responsible for generating the magnetic field that drives the alternator.

4. If the exciter is working correctly, check the diodes in the alternator. Diodes are responsible for converting the alternating current (AC) produced by the alternator into direct current (DC), so a failed diode can cause problems with the alternator.

5. If you have checked all these components and are still having issues with the alternator, you may need to consult a professional mechanic or generator technician to diagnose and fix the problem.