Suspicious of the alternator belt.
I have a Cadillac Seville with 144,000 miles. It is the 8-6-4 engine, but the computer has been disconnected, so it only runs on eight cylinders. My problem is that I have a squealing noise from the alternator whenever I impose a load on it (turn the A/C on, or turn on the lights, then start the engine). I have changed the alternator twice, but it hasn't stopped the noise. Someone suggested the "voltage regulator," but with all this electronic "stuff" these days, I don't even know if I have one or where to find it. Please help!
TOM: You do have a voltage regulator, Chaz, but it happens to be built right into the alternator. So if you've changed the alternator twice, you've changed the voltage regulator twice, too. So that's not the problem.
RAY: I'd be more suspicious of the alternator belt. The squealing symptoms you describe are classic. It may look fine to you, but it's probably old, glazed, and slipping (kind of like my brother).
TOM: If changing the belt doesn't stop the noise, the next thing I'd check would be the alignment of the pulleys. If the alternator belt pulley isn't lined up exactly with the other pulleys, that can also cause the belt to squeal under load.
RAY: And by the way, Chaz, you're awfully lucky that this 8-6-4 engine is stuck in the "eight cylinder" mode. My brother's '63 Dodge Dart has similar technology. It has a 6-3-0 engine. And it alternates between three and zero!