Bad Alternator?

[ashner19]

2001 Explorer sport 199k miles

Battery only 6 months old. Recently put in a new starter. Drove 500 miles last week with no issues.

Today I noticed the battery light stay on for the first time after starting. Light would go away while accelerating but voltage meter was very low. Had battery tested at auto parts store and tested ok but alternator test said not charging/diodes ok. Drove it home and checked the belt and tensioner and cleaned all battery connections. Battery is now reading 11.85 and truck will not start.

How likely is it the alternator went bad seemingly overnight? Why would the battery drop below 12? Is it possible a loose electrical connection with the starter caused this? Are there other things i should be looking at or should i just replace the alternator?

Any ideas, suggestions, advice appreciated

 

[1998Exp]

Your battery is reading 11.85V because it's not being charged. No, a loose connection to the starter did not cause this -- almost certainly your alternator bit the dust, and if it's original, at a very ripe age; most don't last that long. If you are handy, they are not that difficult to rebuild, and the result is likely to be much better than the "remans' found in the auto parts stores. Search this forum; I believe that someone recently posted very detailed, illustrated rebuilding process instructions.

 

[donalds]

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

 

[Pete Deering]

What is the mileage? My dash lights would dim and get brighter when I gave it gas. I replaced it with a new alternator from AutoZone( lifetime). I don't buy rebuilts after a starter problem. But a voltage meter across the battery, with the car running, turn the lights on the voltage should be 14 + - volts. If not its the alternator.

 

[Gary Crist]

Look this over.

How to: - First gen Explorer and others alternator full testing

General Charging System Tests When performing charging system tests, turn off all lamps and electrical components. Place the transmission in NEUTRAL and apply the parking brake. Before performing general charging system tests, make sure the battery is fully charged. Base Voltage Test 1...

www.explorerforum.com

 

[C420sailor]

If the alt is original, that’s a really good run.

And if it IS original, REBUILD IT. The OEM alternators are very high quality.