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2nd Alternator in 3 months

Any suggestions as to why the bearing on the alternator I installed less than three months ago seems to be on its way out again?
The first one may have legitimately worn out, the refurbished alternator (from Rock Auto) I have on there now which has developed a steady, rapid, clicking/knocking, may just have been a dud?
Are shims often involved with installing alternators?

Cheap replacement. There are good rebuilders and there are bad rebuilders. Many of the national chains buy the cheapest they can…so may not be the best rebuilder.

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It’s a “Remy” alternator; anyone have experience with these? Id rather not replace it with another generator just to have that one kick out too, and the problem turn out to be something other than a faulty part. Ie missing shims etc

on most of the alternators I have seen, there is a moving “shim/spacer” in one of the mounting points. One that automatically adjusts as you tighten it. Personally, I’ve never seen an added shim in an alternator.

bad bearings happen. Verify that it is the alternator, though. You could have an idler pulley or tensioner going out.

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Any chance this could be a faulty belt tensioner echoing through the alternator?

Not being too familiar with Charger alternators, could it be that this model is equipped with the clutch type pulley?
If so, maybe the alternator was remanned and the clutch type pulley was not replaced.

If the belt tensioner is faulty maybe this is causing the clutch type pulley to act up??

Just a few wildly random guesses…

Ill have to look into the “shim/spacer” you mentioned. Interesting that its only on one of the mounting points, and that it automatically adjusts as you tighten it. I didn’t see anything like that when I removed the original alternator, (could have fallen out without me seeing it), and the remanned one didn’t include one.
Ill have to pull the belt off and have a look at the idler and tensioner pulleys. Cheers!

No it doesn’t have the clutch type pulley. Ill have to pull the belt off and properly inspect the pulleys. Thanks for your suggestions.:+1:

I would think that Rock Auto would guarantee this one and replace it. The only problem there, is that you will have to pull the bad alternator off and send it in. Then wait until they get you another shipped.

I got a bad bearing from them once. It seems that as soon as I printed the shipping label…the replacement was already shipped. I think I got the replacement in only two days.

Another good reason to buy from a local store and keep your receipt…Take it off…drive to the store and get a replacement.


Yep, they’re covering it under warranty. The way it works is you buy the replacement, same model as original, install it, and then send the faulty part back to them. Then they give you a refund for the replacement, the core charge you paid when buying replacement, and the price of basic ground shipping.
Not too bad, with any luck Ill have the replacement installed for the road trip we have planned this weekend.

It’s likely just a bad replacement alternator. Many parts stores have an alternator testing fixture. Other causes might be the pulley’s are not all aligned to the same plane, the wrong type of pulley on the alternator (make sure it looks and measures like the original one, esp the groove pattern), the belt tension, or it just sounds like it is coming from the alternator but isn’t (use a mechanic’s stethoscope or length of discarded garden hose to decide.)