I have a 2000 Toyota Camry with the L4 5S-FE engine. The car has 140k miles on it. When I first start it, the alternator whines fairly loudly. I narrowed it down by ear, then used the typical stethoscope and it sounds like a bearing in the alternator. (The whine is audible in the stethoscope when the tip is placed on the housing of the alternator)
I suspected the alternator was on the way out as coming to lights behind other cars, I noticed that once the car settled down to it's idle RPM the headlights would dim somewhat.
Side note: The noise is pretty bad when the car is first started, but gets quieter as the car warms up.
Thinking that the alternator could be on the way out I tested the voltage at the battery under various engine RPM as well as when the engine is off. Here are the results:
Engine off: 13.85 VDC (just the battery voltage, so the battery is healthy and charged). The table and chart list a high and low voltage because even without any RPM change, the voltage varied between these values. Probably from various things pulling current on and off. I didn't use an oscilloscope so I did not note any patterns in the variations.
So, my questions:
- Is the curve a healthy one for an alternator? (Keeping in mind the headlights were on low beam during the test as well as all marker lights)
- Is the whine my early warning that one of the bearings in the alternator is going and I need to be prepared to replace it?
- I realize no one has a crystal ball, but is there is typical time frame from the time the noise starts until I'm left stranded?
- How serious is that 1/2 volt jump between 500 and 1000 RPM?