Alternator for a 2000 Sienna

Whining noises that match engine speed are usually associated with the alternator or power steering pump. Water pumps tend to leak before they make a lot of noise.

I do not know if rebuild kits are available for your alternator, and you will need pullers in order to change the bearings. If you decide to install a remanufactured alternator, I recommend getting one from a Toyota dealer. The remanufactured alternators sold by Toyota dealers are 100% tested so they are pretty good quality. I've heard stories of bad remanufactured alternators from auto parts stores, requiring several exchanges before getting a good one. While you're at it, it would be worthwhile to change the drive belt if you have more than 60,000 miles on it.

Changing an alternator should not be difficult if you have a basic metric socket set and a pry bar.

Every older Sienna I've ever worked on has a high-pitched whine coming from the alternator. In the begining we tried replacing and rebuilding units, but the noise always persisted. Eventually all the owners gave up and got used to it as there never really has been a problem beyond the noise.

That's what the Ford dealer told me when I kept taking my 97 F-150 in for the constant rattling from every orifice it had. "This is not a Toyota, this is a Ford. Get used to the rattling."

"Every older Sienna I've ever worked on has a high-pitched whine coming from the alternator. "

May I ask if the noise you were referring to a kind of constant "background" noise ? The noise in my van comes and goes, and when it appears it gets louder if I rev up the engine.

"Changing an alternator should not be difficult if you have a basic metric socket set and a pry bar. "

Can you tell me how do I set the belt tension ? There seems to be two bolts holding the alternator in place, and a third bolt use for adjusting. Do I use the third bolt for adjusting belt tension ? And how do I know how tight is tight enough ?

Thanks again for sharing your knowledge.

I have never taken a look to see how the alternator is set up in a Sienna - qslm can give much better advice there. If there are 3 bolts, most likely,

1 bolt serves as a pivot, another serves to adjust, and the last one locks and holds the adjustment.

The proper way to check belt tension is with a belt tension gauge. The factory manual will have specifications for a new and used belt. The seat-of the pants way is to push down on the belt between pulleys and see how much it deflects. On an older belt, an inch to an inch and a half is OK. If the belt is slipping, you will probably hear it squeal/screech. If it is not squealing/screeching, then it is probably tight enough.

Be aware that it is possible to have a belt that is too tight. If the belt is too tight, over time, it may ruin the bearings on the accessories being driven, like the power steering pump, alternator, and AC compressor.

Deflection has no meaning unless you specify the length of that section of belt and/or a pressure to apply. A longer run will deflect much more than a shorter length and the more pressure you apply, the more deflection you'll get.

-Bruce

True, which is why I called it "seat of the pants."