Whining sound from alternator area...

[cngizbleevng]

2 months ago the alternator and battery died in my 2003 Explorer leaving me stranded at the side of the road during on of our snow storms here.

I had the car towed to Sears Auto Center since it was in the mall I work at. They replaced the battery and alternator and things have been fine until about a week or so ago, when I noticed an unusual whine coming from the engine compartment.

Popping the hood, this is what it sounds like...

http://youtu.be/JnLnaUuBkc8

I had the same auto center check it today, and they said tests of the alternator show it to be functioning fully and that the whining sound should therefore be normal. The manager did say he'd contact the manufacturer/refurbisher and see if there were any known problems or if they had any suggestions.

My main concern is that the whine not get worse, or be a sign of some other problem. The sound seems to be emanating from either the alternator or the box behind it--it's kind of hard to localize exactly (I did use a rubber tube to try to do that).

What do you guys think?

 

[cngizbleevng]

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[cngizbleevng]

Bump

 

[imp]

Best thing you can do is make up a mickey-mouse stethoscope. Several foot long length of rubber tubing, around 1/4-3/8 inch inside diameter, works, as does a long screwdriver, the tip being placed firmly against the suspected noise culprit, the end of the handle pressed against the earlobe, pushing it shut.

The noise could be a bearing, water pump, fan clutch, idler pulley, tensioner are likely possibilities. It has to be done carefully. Don't get tangled in the fan or belt!

If it's the alternator, the sound will be loudest when you probe it. If louder elsewhere, the alternator is likely not the source.

I've used the approach to segregate out possibilities on rear gear housing vs. wheel bearings very successfully. imp

 

[High_Order1]

Hi!
The newer 6G series alternators have a one way clutch in them. When you accelerate hard, then let off (like shifting), the belt slows and it affects the rotational force of the alternator.

With a clutch, if the rpms meet or exceed what the alt is doing, the clutch engages and pushes the alt. If they are less, the alt freewheels like a bicycle.

This can sometimes make a noise, especially if you rev it up and kill it. A louder noise can be a sign of that clutch failing.

Shawn

 

[cross6]

These alternators are famous for high pitched bearing whine. Remans, especially.

Can hear it as constant bearing noise with a mechanic's stethoscope.

 

[Sedition]

My alt makes that noise when I'm having battery issues. In the past it has done it when the battery had a dead cell (required replacement) and when my new battery was low on water.

 

[Number4]

These vehicles don't have the decoupler type pulley.
They should not make a whine noise. If it is the alternator, it needs to be warranted.