Hey Guys,

I've got an 02 excursion 7.3 that has been plagued with alternator problems. I'm now on my 4th alternator. I just got back from a 1000 mile trip and was able to limp it home on batteries and a brand new autolite alternator. The trip down to LA/San Diego went well but the following day I noticed a humming sound. I'm familiar with this humming sound being related to the alternator so I immediately pull out my multi-meter and I probe both batteries while its running. I get a 12.20v. Had my buddy rev it up and the voltage didn't move.

I ran to Kragen and had a choice between rebuilt and new. I went new for $25 more and a lifetime warranty. Replaced the alternator in the Disneyland parking garage, took 10 mins. I start her up and i get 12.7v. (I just today found out that there is a 60 second delay in the alternator turning on). I didn't know that at Disneyland but I shrugged it off and was happy I was getting a partial charge. I didn't want to sweat it too much and have my family worry so I closed the hood and drove down to San Diego. No issues, I was up and down Rancho Santa Fe/San Diego hills with absolutely no issues until the trip home yesterday.

Just as I peak the 4400ft 6% Grapevine pass my battery light starts flickering. ****! I make it down the grapevine and I pull over. I probe the battery and I see 12.02v. I've got about 300 miles to go I decide to run her home and not shut down. I pulled over the next 100 miles and I see 9.05v. At this point my windows/radio/cigarette lighters aren't working. I'm thinking I might not make it on just batteries alone so I ask for the nearest parts store and it's 30 miles away. I decide to call Aaron (nation) who is about the only powerstroker i've got a number to try and diagnose. As I hang up after leaving a message, I notice my a/c blower get stronger. I step outside and probe the batteries and the alternator is giving it 12.6 - 12.7. I decide to run the 200 miles all the way. The battery light stays off up until 2 miles from home and it starts flickering again. We made it home.

I woke up this morning. Disconnected all battery wires and load tested the battery (trying to keep it simple at this point). Batteries both tested well on a 10 second load tester. Cleaned all 4 terminals and connectors which were somewhat dirty. I start her up and i get 12.7.... after 60 seconds it jumps to 13.90v at the alternator and 13.84v at the driver side battery. (Per nation, I check the 2-wire harness running to the alternator and all seems ok, but I have yet to peel away the entire loom that runs along the engine block to check for any open/shorts.) So the battery light is gone and i'm now getting 13.8v on a cold engine. I get in to rev the engine and when I pass about 1800rpm revs the battery light comes on and flickers and then shuts off as the rpms drop. Give my pop a call and he says could be the belt slipping. I kinda agree but I don't see the belt looking loose when I rev it. No belt bounce or anything. What do you guys think? Shot brand new autolite alternator?

Thanks in advance.

Erik

 

I don't know the answer, but the 60 sec delay is likely the glow plugs drawing that juice and the voltage spikes when they kick off.

My alt is now the opposite of your problem. Mine is putting out toooo much. Well over 15v and I can actually see the batt gauge surging! I bought a brand new NAPA once and it lasted 1 week. Still have it sitting in a box.

Where in the Bay Area are you located? Maybe we can play alternators sometime...

 

I'm in San Leandro. I now have 2 alternators. 1 was purchased here at my favorite local shop. The other was purchased at Kragen with a lifetime warranty.

I just called my local shop here and they will honor the warranty on their alternator. I'm starting to wonder if the brand new autolite one I got at Kragen went bad too.

 

The voltage regulator is in the alternator right?

 

I'm pretty sure the reg is internal in the alt. I think my brand new one just fried the reg and not the whole shabang.

There are threads out there that deal with rebuilding or fixing alternators, but I'm at work right now and can't spend much time looking for them!

Come down next time we have a GTG at my house!

 

Are you pulling a trailer that has low batteries and the alternator has to charge them back up or something?
Four alternators in a row like that, I would be trying to figure out what is taking these alternators out.

 

I was having battery/charging problems as well. Batteries kept dying, alt. wouldn't put out a good charge, etc. First thing I did was changed out the starter. Even though it was working, it would turn over slow even with new batteries. After the new starter I replaced the batteries through the warranty and then about a month later the alt. died. I've read several stories like this regarding multiple alternator failures from the chain stores so I bought one from here:

https://www.dcpowerinc.com/8316-190-oem.html
yeah it's expensive but I was out of town and a FTE member (soutthpaw, thanks again DJ) installed it for me. We've had no issues since, Ex runs better and it's piece of mind.

I should add that I'm at 200k and don't know when the alt, if ever was replaced...or the starter for that matter

 

Check the large terminal and cable at the alternator. I had similar problem (flickering batt light) and cured it by replacing the cable terminal. I just cut off the old one and crimped on a new one after applying Noalox on the cable and inside the terminal. Must have been a continuity problem between the terminal and cable. No flickering since.

 

Ok, i'm going to pull apart the looming on the harness either today or this weekend. Does the large wire running from the alternator run directly to the battery? If so, I can replace it. I was also thinking of running a larger 2 gauge wire directly from the alternator post to the battery with a 130a breaker in the middle.

My concern is that little 2 wire harness. I really don't want to peel away the entire harness since it's all nice a neat right now.

I believe the alternator is a 100a or 130a, I will have to check. I have an Avic head unit, 3 screens in the back and 1 screen on the passenger visor (no I didn't put these in, the previous owner did), a dvd in the back and a dp-tuner. All these are never on at the same time, maybe 1 screen at a time.

 

I am with Dan on this one, here must be some bad connections or connectors on the cables. I think I would be taking all the connections apart to clean the contact points down to shiny metal and and apply a dialectic grease (Noalox) before reassembly. Look for discoloration from heat on all the connections.

 

Been down this road before...my first one went bad and I ended up with a duralast Gold from Autozone. I had 2 or 3 that held for awhile, but then the regulator went out and would start over charging the batteries. I'm on my 4th one now and it's doing a great job keeping my batteries charged. Best of all it's free if it ever decides to crap out again...

 

I'm going to re-clean the contacts today, do you guys use anything special to get rid of that white powdery substance on the battery terminals? There is a slight build-up of it on the driver's side positive terminal.

Also, which battery gets fed current from alternator first? I know there is a positive cable running between the two batteries.

 

stangclassic66,
If I were you, I would remove both batteries out of the truck to clean them and the battery trays. Ordinary baking soda will neutralize the acid (white powder), follow this with a good cleaning of the entire battery and the trays with a degreaser followed with a rinse of water. You might notice that there is some corrosian on the tray if it is made of metal, in that case it's time to do some painting. Clean the battery posts and terminals inside and out down to a shiny surface. Coat the terminals and connectors inside and out with a dielectric grease (Noalox) to seal the connection. Reassemble the truck and you will be good to go until next year.

 

Well I have been messing with my charging system all day. replaced all the cable connections and terminals at the battery, there was corrosion inside the OEM terminals on the pass side that was causing resistance to not let the alternator charge. I cut them open with the grinder to look at the condition of them) The DB alternator took a dump a few months back so I now put them on my black list. May order up one of the DC power alternators like I put on Aric's truck. Have a auto parts store one on there now and its charging now with the new terminals/cables and connections but still low voltage at about 13 VDC. its probably taken a **** too which is very common with these cheap replacements but its a lifetime warranty so I can just drive over and get it checked and replaced....

 

I too have had alt problems . So I don't think I can be much help. I read a tread about replacing terminals with marine ones which I am going to do. Also I got a gauge that plugs into cig lighter since my problem is only when going down the road . See if any of this helps. https://www.ford-trucks.com/forums/1...ght-gauge.html
I think you have a bigger issue than just the alt. Good luck