Car alternator issue - how to fix it?

Hi
i recently got the alternator replaced, new one, in my 2004 ford card
but was getting a motor running like noise. When am idling or on slow speed.
why is that
anything to be replaced internally.
i thought alternators gets replaced as a whole.
what to look for when buying a alternator and which brand is better.

Sounds like the tensioner bearing is worn out, you may not have needed a new alternator at all

You need to have someone with mechanical knowledge look at your vehicle for a diagnosis

Could be ancillary belt tensioner etc.
If you didn't have issues with charging battery or headlights dipping when all fans etc on id say alternator was ok in the first place

It sounds like the tension idle wheel might have warn bearings or is faulty and those are known to go.I've even seen so brand new or rebuilt or used alternators that were faulty.Sometimes improper tensions or a faulty belt causes odd noises.It is also possible that the shop installed a defective alternator.I'am not sure from what you've stated if the shop supplied the alternator or if you supplied the alternator. Usually a shop will only warranty their labour if the shop supplies/sells the customer the replacement parts.

In most cases what ppl or mechanics end up purchasing is a rebuilt alternator.

Some of the so called new alternators are in fact rebuilt and I recommend asking the sales ppl or mechanics not just about the warranty coverage but if the alternator is actually a new alternator or a rebuilt.In most cases a rebuilt alternator is sold with a reasonable warranty, some even have life time warranties. You can actually find alternators out there that are supposedly brand new that are 50% to 100% or more expensive then the rebuilt alternators but the warranty is the same or even less then the lower cost rebuilt alternators. I don't think it much matters about the brand names just bec again most are rebuilt anyways.Note that most auto part stores require the old alternator's as a refundable core value.Meaning there's the core charge on top of the purchase price if you don't have your old one with you.

I might suggest or recommend when the original factory installed alternators fail that you get them rebuilt. Plus if I was going to purchase a alternator I'd probably go with the ones that come with a good full replacement warranty but aren't too expensive.Personally I usually just end up pulling one out of a car at the local auto wreckers.

Hope that helps and best of luck.By the way if the shop is a respectful business they usually will check and diagnose such noise issues for you at no extra charge or for little extra cost since they did the original alternator replacement work.