Based on the below, I assume that means I need to replace the alternator ? | Ford Explorer Forums - Serious Explorations

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Based on the below, I assume that means I need to replace the alternator ?

2004mountaineers

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Year, Model & Trim Level
2004 Mercury Mountaineer
Battery light came on, on the dash, a couple days ago.
Based on the below, I assume that means I need to replace the alternator ?

7/29/23:
With a fully charged battery:
engine off: battery voltage = 12.95volts (volt-meter)
engine on (idling): battery voltage = 12.67volts (volt-meter)

Seems that probably means the alternator needs to be replaced.
edit: (battery is almost brand new)

2004 Mercury Mountaineer, 4liter, v6, awd
 



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Alternator would be my first suspect, if there wasn’t a reason to believe there was belt slippage, or something else very obvious.
 






Yes, either that or you have a bad electrical connection between them. I assume you checked for clamp tightness and corrosion?
 






battery terminals are tight/valid. no belt slippage.
I guess there could still be a bad connection somewhere between the battery and alternator.
This guy lists a bunch of other tests...
 






Many auto parts stores have an alternator test jig set up. It won't catch all alternator faults but is worth trying if not too much trouble to remove and reinstall it.

At the same time, there are many mixed feeling about a good replacement alternator. Some prefer DIY rebuild or have a local shop rebuild, or buy a new Motorcraft or major brand like Bosch, or risk lifetime warranty for a remanufactured unit at an auto parts shop. The one thing I would not do above all other options/gambles, is buy a reman from an auto parts shop without a lifetime warranty.

I don't know the history of the vehicle but based on all you've stated, it seems (most likely) that it just needs a new alternator.
 






First check to see if your vehicle has an alternator fuse. Many fords actually have a fuse in the power dist box for the alternator charging circuit. This is the wire that powers the alternator internal voltage regulator. If that fuse blows then you get a battery light and no charging. Some years use a physical fusible link and some actually have a fuse in the fuse box. Always check before assuming alt went bad

Only replace with a new alternator never reman. I will pretty much only buy Bosch or
Motorcraft new alternators, I have replaced three so far this year, one was on a 2008 Taurus what a huge job that was
 






Battery light came on, on the dash, a couple days ago.
Based on the below, I assume that means I need to replace the alternator ?

7/29/23:
With a fully charged battery:
engine off: battery voltage = 12.95volts (volt-meter)
engine on (idling): battery voltage = 12.67volts (volt-meter)

Seems that probably means the alternator needs to be replaced.
edit: (battery is almost brand new)

2004 Mercury Mountaineer, 4liter, v6, awd

How much heat has your battery been under? Heat kills batteries
 












First check to see if your vehicle has an alternator fuse. Many fords actually have a fuse in the power dist box for the alternator charging circuit. This is the wire that powers the alternator internal voltage regulator. If that fuse blows then you get a battery light and no charging. Some years use a physical fusible link and some actually have a fuse in the fuse box. Always check before assuming alt went bad

Only replace with a new alternator never reman. I will pretty much only buy Bosch or
Motorcraft new alternators, I have replaced three so far this year, one was on a 2008 Taurus what a huge job that was
Upon scanning this video, I don't see any fuse listed as an alternator fuse.

 






My vote is to go to autozone or something and ask them to test it. They will do it for free. When mine went, they tested it and it was indeed bad.

Replacing the alternator will take you about an hour taking your time. just get a breaker bar on the belt tensioner to get the belt off, 3 bolts and 2 connectors IIRC. Very easy to access. I just threw a cheap one from autozone in there because it was sunday and they were the only ones open. I could literally do it again in a parking lot with tools I keep in the truck so I'm not worried about another failure.
 






I also checked and do not see an “alt” or “gen”’fuse so it’s safe to assume your truck uses a fusible
Link
These would be grey in color and near the red wire where it hooks to battery. They wrap the harness so the fusible links are exposed, pretty easy to see if they burned up. Also a continuity check from battery + terminal wire to alternator yellow/white wire would tell if they are still good.
Nothing sucks worse then installing a new alternator to find out it was just a fuse
 






The new alternator finally arrived. I swapped it in.

8/3/23:
engine off: battery voltage = 12.75volts (volt-meter)
engine on (idling): battery voltage = 14.33volts (volt-meter)

And, the red battery light on the dash is now gone.
So, replacing the alternator seems to have cured the vehicle (keeping fingers crossed).

Total cost: $85.99 (new alternator from ebay).

EDIT: I don't know if places like O'Reilly's will give a person anything for the old alternator if you bought the new one on ebay...
 






The new alternator finally arrived. I swapped it in.

8/3/23:
engine off: battery voltage = 12.75volts (volt-meter)
engine on (idling): battery voltage = 14.33volts (volt-meter)

And, the red battery light on the dash is now gone.
So, replacing the alternator seems to have cured the vehicle (keeping fingers crossed).

Total cost: $85.99 (new alternator from ebay).

EDIT: I don't know if places like O'Reilly's will give a person anything for the old alternator if you bought the new one on ebay...
No, That like saying you are going too a dentist for heart surgery, in place of a heart doctor.
rebuilt it and save it as a spare
Did the eBay seller ask for the core?
Did you get charge for the core?
New alternator'--no core return
Remain unit core charge
 






No, That like saying you are going too a dentist for heart surgery, in place of a heart doctor.
rebuilt it and save it as a spare
Did the eBay seller ask for the core?
Did you get charge for the core?
New alternator'--no core return
Remain unit core charge
/////////////////////
For below, the answers are both no.
"Did the eBay seller ask for the core?
Did you get charge for the core?"
So, I am about to simply chuck the old alternator into the dumpster.
///////////////////////
 






I’ve never purchased any new parts in person they didn’t take a core charge for.

On EBay, that makes sense. The Motorcraft units are better to rebuild than a remanufactured unit. Someone here might want to buy it for a little more than the shipping.
 






Brand new alternator $85 on eBay? You might want to buy two and keep one in the truck! What brand is it?
 












I usually see a year or less
From one of those, but sometimes they last forever! I wish you well!
 






Keep the old alternator, you may end up wanting to rebuild it.
 



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Anybody got a link to rebuild parts for these?
 






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