2004 F250 w/ 6.0 Diesel. Hauled a few horses yesterday, went out today to properly park the truck and unhook the trailer only to notice the battery light was still on after Id moved everything to its proper place and unhooked the horse trailer.

Truck cranks fast, starts quickly. With truck off, I put a volt meter on both batteries... got 11.6 and 11.8V respectively.

With vehicle running.... voltage was the same.

Tested with the vehicle at the alternator while it was running and got 11.8V.

Put a block on the accelerator to revv the engine a bit to see if the alternator voltage increased.... it did not. Stayed at 11.8V.

The truck was at temperature when i was testing as I did it after moving it around to park the trailer before i noticed the charging light was on.

My sensibilities say the alternator is toast and needs to be replaced.... but I just wanted to double check with folks that know these trucks better than I.

Replacing said alternator doesn't look terribly challenging, slip belt off, 3 nuts 2 wire connectors and Bob's your uncle.

But I don't want to just throw parts at it. I want to be sure.

Thank you in advance for the input/insight.

 

Alternator is toast. Looks like it's showing battery voltage at alternator. Alternator should read 13.3 or above when testing while running.

 

Thank you for your input. It is appreciated. If my alternator reading was battery voltage....I have to ask: do these things just "go" like that? It was running/charging fine yesterday. No indication of troubles until today. I've never had an alternator just go out like this before. Especially odd is that it didn't increase voltage at all when I increased engine speed.

Is there anything else I should check before I throw an alternator at this thing?

 

Mine went out about a year ago on the interstate. Wrench light came on. I pulled over next exit. Check with voltmeter, witch I have in my toolbox. Toast!! That quick. I have torque Pro on a Tablet running when I drive. I could see it on vehicle power. I was only running about 12 volts where I should have been around 13. 6-8. I pulled over before I drained batteries. It happens.

 

How old are the batteries ? You could have a compound issue.

Hobo

 

Testing at alternator will still read 13.4 or so. My batteries read 12.4 just lifting hood. After start about 11.6 then a few seconds of idleing you v regulator will kick in and put out 13.4 to 14 something depending on your setup.
I would load test batteries also just for ease of mind

 

So with the concensus being the alternator is now a paperweight.... any advice on getting the old one off?

The big challenge to me seems to be the drive belt. Anyone have instructions or an easy trick to release it.

Otherwise, 3 bolts and two wiring connectors don't seem to be that much of a noodle scratcher.... (although I'm sure they won't want to come off/loose easily).

 

Also.... batteries are about 1.5 yrs old and have less than 10k miles of use.

 

You can just pull up on the belt and use the little lever underneath to hold it in place. Takes a strong arm and free hand. Other than that just rent a pulley wrench from your auto store and us it.

 

I'd take them up to parts store and have tested when you rent the tool. Tool doesn't really cost anything. They'll put it on your card when you take it, and refund money when you return it.

 

https://www.northerntool.com/shop/to...rce=Google_LIA

That's what it looks like.

 

Make sure those batteries are tested for shorted cells. Anytime a starting battery gets wallopped pretty good and severely discharged it should be thoroughly charged up (this will take a while) and tested. They don't "like" hanging around 10 or 11 volts. It isn't a certainty they will be damaged but it is a possibility. Charge them sooner rather than later. The alternator can't do this, spend a couple days letting them cook on the charger and get plussed up before marrying them up with your fresh alternator. Serving suggestion.

Generally speaking a defective battery can damage an alternator and, a defective alternator can also damage a battery, so it's kind of a package deal when it comes to testing the electrical system. While the batts are out charging and stuff is hanging there where the alternator used to live, it would be a real good opportunity to clean battery ground connections, they might "look" good bit make sure they are shiny metal, and tightened securely. The alternator gets its ground through the flanges and hdwre connecting to block.

 

I wish I had a dollar everytime someone posted back after being advised to get the batteries charged and load tested and said: "But they are only a year old", lol.

Nice post Tedster9

 

Folks, Thank you for your suggestions and tech advice. Truck is fixed (for now).

Went to O'Reilly's this AM and got a remanufactured uprated alternator. After some pulling/tugging/wrenching and fingers crossing.... all is good and the charging light is off.

Right from the off, testing voltage was 13.89. Batteries have charged to better than 12.5v in short order. Will hook them to a charging station tonight.

Had them tested when I turned in the core charge and all is "supposedly" good.

Thank you again for the suggestions, it was greatly appreciated.