Alternator working fine after 15+ years--should I replace it as a precaution?

[froglady99]

I've had my 2003 Explorer XLT for a little over 15 years, and it has about 183,000 miles on it. I've never had my alternator replaced in all that time--it seems to still be working fine. But after seeing the alternator go out on my sister's car of a similar age (different make/model), I'm wondering if I should consider replacing my alternator as a precaution. What do you think? Is it better to leave it as it is until there are signs of a problem, or should I just replace it this summer since it's at least 15 years old?

 

[Mr. Alligator]

i would not replace your working stock alternator, unless there is any problem with function. I understand your logic, but you will almost certainly only be able to find less effective (Chinese) replacements. And you will have so many other parts to replace in your older truck.

You stand a very real chance of getting a malfunctioning part out of the box, and an even greater chance of creating a far more frequent maintenance issue. Or, maybe it will work just fine, like the alternator you already have.

IF you want, obtain a replacement alternator, but do not change it yet… just my opinion.

Good luck and drive safe,

 

[J_C]

I agree, wait for it to fail unless that would cause a special hardship, some kind of life threatening situation, and in that case spend the big bucks on a new major brand alternator, or better still, get a newer vehicle with less wear on it.

Then again if it makes you sleep better at night... there are worse ways to spend money. I wouldn't swap a working OEM alternator with a generic rebuilt one.

 

[LMHmedchem]

I agree with what is said above with one caveat. Parts, especially quality parts, are getting harder to find for these older trucks. As mentioned, for many parts it is already not possible to get anything other than Chinese manufactured replacements that may actually last less time than your 15 year old OE alternator. There are many Chinese manufactured parts that are fine but I wouldn't rush into installing one unless I didn't have any other choice.

I think a new Remy,

REMY 92516 Gold 130A Alternator ($139.79 +ship)

or a remanufactured Remy, Denso, or Bosch,

REMY 23687 Premium Remanufactured 130A Alternator ($89.79 $40 core, +ship)
DENSO 2105313 First Time Fit Remanufactured 130A Alternator w/o Black Rear Cover ($114.99, $34 core +ship)
BOSCH AL7541X Remanufactured 130A Alternator ($117.79, $40 core, +ship)

will be a quality product and give good service. I new Bosch or Motorcraft would be the best option but neither of these are listed at RockAuto. That doesn't mean that they are not available but it may take some looking. A new Motorcraft will be expensive, even if you can find it. I think that ACDelco parts are quality as well. A remanufactured Motorcraft should also be a good part but I not sure I would pay more for that then for a new Remy.

I would keep your OE alternator on your truck until it stops working, but I don't think it would be silly to buy one of these and keep it on hand in case your original alternator fails. Keep in mind that if you buy a part like that it will likely be out of warranty before you install it, so that is one downside. I watch for parts that I know I may eventually need and see when they are on sale. I have a box in the basement with a few things that I will likely need to change out at some point. Worst case I will sell them on ebay.

Periodically check the output of your alternator in volts. Just connect the red lead of a DMM to the red terminal on the alternator and the black lead to the black terminal on your battery. Check the amps at idle and at 1000 rpm. If you notice the amps dropping below 14 or so then you might want to think about changing it out.

Also check the 4 idler pulleys on the engine block and the tensioner. The bearings go in these and if you do have to replace the alternator, it will be a good time to do some related maintained. Sometimes what looks like a bad alternator is actually a worn out tensioner or a stretched belt. The alternator rpms/amps will drop without the proper tension on the belt.

LMHmedchem

 

[J_C]

Periodically check the output of your alternator in amps. Just connect the red lead of a DMM to the red terminal on the alternator and the black lead to the black terminal on your battery. Check the amps at idle and at 1000 rpm. If you notice the amps dropping in the future then you can change it out.

I'm probably misunderstanding what you are stating to do, but from how I'm interpreting it, wouldn't work.

If you connect the red (positive) lead of a DMM to alternator positive, and the black lead to battery ground, in current measurement mode you are creating (very nearly) a dead short on the battery and will definitely blow a DMM fuse or melt the wires if not worse.

If you disconnect the existing battery positive wire going to the battery, at the alternator, you could still potentially be putting too many amps through the DMM for it to handle, many have 10A, 20A at most current limits. Besides that, you'd want the DMM red lead on the alternator with the cable to battery disconnected, but the black DMM lead would go to the red, positive battery terminal. This is still potentially too much current for the average DMM to handle, but if it could, that seems like the correct hookup.

IMO, anything capable of more current than a DMM can handle, ought to use a DC clamp meter to measure it instead.

 

[mountaineer2004]

My alt went at 175k, so it probably won't last much longer.

If you like to do things on your schedule, replace it now with OEM....especially if you plan on keeping it for a while.

 

[LMHmedchem]

I'm probably misunderstanding what you are stating to do, but from how I'm interpreting it, wouldn't work.

If you connect the red (positive) lead of a DMM to alternator positive, and the black lead to battery ground, in current measurement mode you are creating (very nearly) a dead short on the battery and will definitely blow a DMM fuse or melt the wires if not worse.

Sorry, I seem to be partially brain dead today. I meant to test the output in volts, not amps. I have made an edit to my original post to correct this before someone goes and melts their DMM. A DMM to measure amps on an alternator with up to 130A output is not a good idea.

The volt test should be from the red terminal on the alternator to a ground. I have sometimes found the engine grounds to be corroded enough to get a false low reading so I use the negative battery terminal instead. This has always worked for me, though I would appreciate it if someone would let me know this is a bad idea for some reason.

IMO, anything capable of more current than a DMM can handle, ought to use a DC clamp meter to measure it instead.

This is definitely true.

My alt went at 175k, so it probably won't last much longer.

If you like to do things on your schedule, replace it now with OEM....especially if you plan on keeping it for a while.

I don't know if you will be able to find a new OE Motorcraft alternator. If you can, it could cost as much as $400. I don't think I would pay that much for a part for a 20 year old truck. I generally set my limit at twice the cost of a remanufactured unit from a quality brand. In this case I think I wouldn't pay any more than $175-$200 for Motorcraft.

How long you are planning on keeping the truck is definitely something to consider with all of your maintenance.

LMHmedchem

 

[Mbrooks420]

If you have access to a pick and pull, I’d grab a Motorcraft alternator and rebuilt it.

 

[LMHmedchem]

If you have access to a pick and pull, I’d grab a Motorcraft alternator and rebuilt it.

If you have a link to a high quality alternator rebuild kit for this model that would be great to post. I have one of these in the basement that I plan to rebuild myself if I get time.

LMHmedchem

 

[donalds]

Welcome to Rebuilderinabox! – Rebuilder in a box

 

[J_C]

Here are a couple,

Rebuilder in a box

Home - Alternator Starter Rebuild Kits

Kit look UpToolsAbout UsHelpArticlesHI-AMP Alternators ALTERNATOR & STARTER EDUCATIONAL ARTICLES Our goal is to make our site the most educational starting/charging system site on the web. Rebuilderinabox is dedicated to the real American mechanic in the trenches. Please read our Mission...

alternatorstarterrebuildkits.com

Edit: donalds beat me to it. He didn't mention his excellent pic-heavy topic about it:

How to: - 4g alternator rebuild with pictures

So about a year ago I bought a remanufactured alternator From autocrap Since then the bearings went out twice making lots of noise So instead of changing it again for warranty I figured I may as well rebuild it the correct way and make a how to thread

www.explorerforum.com

 

[LMHmedchem]

Welcome to Rebuilderinabox! – Rebuilder in a box

Out of interest, do you know who makes the bearing in these kits? The smaller one looks like the same bearing that's in the idler pulleys and tensioner.

Looking at the parts on the rebuilder site it looks like the 2003 4.6L uses the 3GP and not the 4GP from the thread of Donalds. I am sure the process is similar but the pictures will probably not all match.

LMHmedchem

 

[donalds]

Out of interest, do you know who makes the bearing in these kits

I have no idea but I do remember that very good quality
There is videos on that website rebuild in a box.com To rebuild your alternator there's a video for every starter and alternator they sell a kit for

 

[Stynx]

FWIW when mine went, I got a new one from autozone and it took all of an hour to remove the old one and install a new one.

It's dead simple - use a breaker bar to move the belt tensioning pully, drop the belt, 3 or 4 screws and I think 2 electrical connectors then pop the belt back on. Probably the easiest repair short of replacing the air filter or headlamp bulb.

I bought whatever crap autozone had because a) it was sunday and I needed one RFN b) they would swap it if it didn't work and c) it had a decent warranty - long enough that if it failed early on I could swap it for a new one. Don't care about motorcraft quality because we probably aren't keeping it for much longer and if we do it's a very simple repair.

Don't sweat it.

 

[Fix4Dirt]

rebuilding is a good option. will say the one on this lasted 23 years and 310k and still worked fine just replied out of precaution.