Hi everyone,

I have a 97 cavalier with a 2.2 engine and the alternator is making a whining noise. When I disconnect the plug that goes into the alternator, the whining sound goes away. The alternator is still charging about 14.2 volts at the battery while the car is running. Anyone have any ideas about what might be going on? I don't have a problem if it needs to be replaced but it works fine except for the whining.

If I have to replace the alternater can anyone recommend a good quality replacement (Bosch, Delco, Duralast, etc.)?

Thanks.

I think you have a diode or diodes shorting, but you are still getting some output from the rest.

Disconnecting (Or reconnecting) the plug with the engine running is not really a good thing to do, voltage spikes can kill the diodes or other electronic items in the system.

What you are doing when you disconnect the plug is disconnecting the rotor coil and "Switching Off" the alternator, so it then makes no noise (But doesn't generate, either)

1.I would try disconnecting the battery and (shiny) cleaning the earth point on the chassis and the cable that connects to it. Reconnect and test for noise.

2, If it's still noisy then it is probably bad diodes and a new alternator will fix it.

I have Delco's (OEM) in both of my '93s and they have both gone over 200,000kms/nearly 136,000miles
so I have not tried any other make.


Hope this helps


Alont

Thanks for the reply, it was the alternator.

Dave