Might need new alternator

So for the past three days or so, I've been hearing this weird whining noise coming from the engine bay. After some recent research, I have found the problem to most likely be the alternator. While driving, the battery light, abs light, and parking brake light came on within a 2-minute span of one another. I was wondering what recommendation do some of you have for a new alternator or what I should do about this problem. Any help would be greatly appreciated!

 

Check the voltage at your battery when it is running and revving. Look for low output as well as possible poor regulation of output when doing so.
You can identify many whines with a long screwdriver placed on your suspect item and the handle to your ear. Unless you have added A LOT of stuff to your vehicle, you probably have no reason to upgrade from OEM parts or recommended sizes. If you have a quality rebuilder nearby, sometimes parts are upgraded internally from OEM configurations with better parts and for less money than new offerings.
I wouldnt replace the alternator until I knew for sure that yours was junk.

 

Disconnect the fieldwire plug from alternator with the engine running. If the whine goes away then the alt is bad

 

The battery light alone indicates a bad battery or bad alternator. The whining sound would seem to pinpoint the alternator. Take truck to an autozone or the like; they will test the charging system at no charge with a handheld diagnostic tool. I've seen the tool up close and it is a nifty device. You could do your own simple tests with a voltmeter and do a load test. Simple to do once you do it. There are many utube videos on this - I like the Chris Fix videos the best.

 

This. Easy diagnosis for the win.

 

Get a voltmeter to check the battery voltage with engine off / idling and a mechanic's stethoscope or long screwdriver to pinpoint the noise. IMO, unplugging the alt won't rule out a faulty battery coupled with noise from another possible pulley such as alt, idler, tensioner, a/c, etc...
Start with cleaning your battery terminals until sparkling clean and tighten before performing any other tests.

 

/\ This is the winner /\

There are a lot of possibilities for the type of alternator failure (worn brushes, bad rectifier, intermittent open circuit in one of the windings, bad regulator) but in the end those are all academic because the simplest solution is to just replace the alternator.

There was a time when rebuilding alternators made more economic sense but in today's world it makes more sense to just swap out the alternator. On this note, I'm a proponent of replacing the brushes in an alternator as a preventative step before the brushes completely fail. However, that step is preventative maintenance and generally not a repair once the alternator has failed.

Also, a battery that is nearing the end of its life will result in the alternator attempting to constantly charge it at a high rate. That can result in that whining noise as well. So if the OP has a battery in that 4-6 year life range, I would suggest load testing the battery as well. In fact, if the battery is beyond that 6 year mark, I would just go ahead and replace it now before the weather gets colder.
You can get yourself into a vicious cycle with bad batteries & alternators. A bad alternator can cause a marginal battery to fail sooner and bad battery can work an alternator harder than normal resulting in a marginal alternator failing sooner than expected.

 

I've found that a local shop that specializes in such things can provide a much better value by rebuilding your current unit than buying a big box reman.

Last one I had done they removed/rebuilt/replaced the unit for 2/3 the $ of buying reman and still having to do the R&R myself. Which, on that particular vehicle, wasn't all that simple.

Something to investigate anyway, ie finding out if such a vendor exists in your locale.

 

OP how many miles did you have before your alt went. Also anyone else welcome to chime in. I'm at 132500 now. Planning on brush replacement this weekend. Tried last weekend but of course lower bolt is rounded so had to get some Irwin extractors.

 

original alt in mine and at 196k miles
I keep my head lights, fog lights on and fan at III all the time

 

Sweet. Never changed the brushes or otherwise serviced the alt?

 

Nothing done to the alt yet

never touched the alt in my 88 toy 4x4 or 99 i4 taco

 

@Benny123 Replaced my OEM alt at 155K with a 200-amp alt from eBay vendor BnR. They didn't required a core; so, I replaced the brushes in the OEM alt and have it as backup. As I recall the old brushes looked good.

 

If you do have a bad alternator, whatever you do, save yourself the headache and don't buy replacement from Autozone/Advance/Oriellys etc - they might look pretty but they are straight junk. Find a local rebuilder, or get a good used OEM unit from a pick-a-part. etc. I have had good luck with Alterstart on ebay as far as rebuilders go.

 

@Chuy I was thinking about doing the same with an old alternator. The only thing I wondered is how long it can sit on a shelf before it goes bad?

 

I got about 330K on my ‘07s original alternator. No maintenance on it but I would’ve replaced the brushes if I knew that was an option...

 

An alt is in your engine bay with heat, cold, water, dirt and stuff and maybe more

on a shelf its protected from those elements

Starter on my 69 140 is original.

I bet an alt on the shelf will last 100 years or more so long as it isn't getting wet

 

@knottyrope Good points. Agreed.

 

@Benny123 ... and protect it from critters moving in. I put the OEM alt in a heavy gauge plastic bag and threw that in the box I got with the replacement alt and threw it on the shelf.