New Alternator, crazy needles, and other summer fun...

[doonze]

Ok, so.... today I'm sitting at a light...... and all of a sudden my A/C blower motor starts blowing much softer, and my blinker starts blinking much slower. I glance at the volt gauge, and it's down below the N in normal....uh oh..... Just for a little history, since I bought it the needle has always stayed at about M to A in normal.

So I look up, and what do I see... O'Reilly's right across the street. Well, that's good at least. Pull in, they test it up. 12.6 volts with the truck off.... 12.3v with the truck started...not good. I didn't feel like just buying what they had without price shopping a bit so I headed home and hit the internet.

Anyway, Autozone had the best deal, so I buy it on line and go to pick it up. When I was about 4 blocks away all of a sudden the voltage needle jumped up to about O in normal. Hmmm.... So when I get there I have them test it again. (they used a tester on wheels, much better then the little hand held thing O'Reilly's had). Other then the manager being a little bit of a di*k, the tester showed it was running around 12 volts and 3 amps max. (that's a bad thing)

Guy told me it was fried so I took the new one home and threw it in, 30 min job, cake. Start her up....needle hanging out at about O, almost exactly where it was just before with the old one. A rev brought it up for a bit, maybe about M, but after driving it back to Autozone to get my core back It settled back to around between O/M. That's 2 letters lower then it stayed at before all this started...

So when I got back to Autozone I have them test the new one.... 13.5 volts and 7.5 amps....much better and it seems to pass the test....so I guess it's ok....

So I have 2 questions.... One, where does you voltage needle sit? And second anyone got a handy Multi Meter and can tell me what kinda volts they push with the engine running??

Thanks!

 

[Iron Weasel]

Needle sits smack dab between the R & M in NORMAL and my meter says 14.83v

 

[shaggymane]

mine runs 14.8 also. I thought that was a bit high, that high 13's or low 14's would be better, you know, so the battery wouldn't cook from over charging.

put a different voltage reg in and it too runs 14.8.

Iron weasel seems to know stuff so I'm good with what he says.

 

[Iron Weasel]

95A alternators should put out 15v.
110 & 130A should put out 14.1 - 14.7v.

Either way, 14.8 or around there is fine. 13.5v is a little low, but as long as the alternator is able to keep up with the electrical load on the vehicle and charge the battery, then you should be fine.

 

[TedJ]

I wouldn't trust comparing different people's in-dash gauges. They do not seem to be very consistent. Mine is a bit weird, and seems to change a lot with only small changes in the actual measured voltage. It's good for seeing that something is wrong after you know where it usually sits, but comparisons to others may not be so useful.

If you are having problems with the voltage regulation, check what kind of regulator there is on your alternator. Motorcraft ones will say motorcraft. The cheap replacements will probably just say "Made in China" on the back. I've had the worst luck with rebuilt alternators, one time I had one which lasted all of 5 seconds(no, really, I started it up, voltmeter went up, then the red light went on and it dropped) The second one worked because it had a re-used motorcraft regulator on it., but it still wasn't the best.

I ended up doing some research, figuring that someone had to be selling better stuff than the crap at the autoparts stores. I found http://www.alternatorparts.com recommended on a bunch of forums so i figured I'd give it a shot. I got a 130a Heavy Duty http://www.alternatorparts.com/Ford_3G.htm

It's a bigger case than the original (still fits fine) and the voltage regulation is dead on, even with the A/C and headlights on at idle. Everything is made in USA and they claim by the same companies that make for the OEM products. Whatever it is it certainly works well, and was worth the higher price.

(disclaimer here, I paid full price and don't know anyone from alternatorparts. I just bought something from them and like it)

 

[doonze]

Thanks guys, I think I was running around 14 something if I remember back last year when we were having the conversation about my needle bouncing around a lot (you were in that thread Ted). I ended up getting the "magic smoke" from my multi meter Maniak is so fond of!! LOL

Well, I got more then smoke, I caught it on fire and melted one of the leads...but still runs like a champ... goooo Harbor Freight!

Anyway, I'm pretty sure the stocker was a 95a, I don't think they would have put a 130a on my 93 sport, and I didn't measure the cases, but they looked pretty much the same. Guess I'm just going to let it ride and see how things go. I'm about 100% sure I'm running at least a volt lower on the "new" rebuilt Alt, but maybe my stocker was iffy? It had always acted weird sometimes, with the bouncing needle and all.

But I watched both test on them in the car, and seems autozone has to "test" the core on return before they can take it, and verify it's bad, and my old one failed both test, so I know it was bad..... I just think my shiny new reman just isn't putting out the volts the stocker did, but maybe that stocker was over charging and that's what caused it to fail anyway??!?

I'll post up if I get any more results....again, thanks guys!

 

[92exp4x4]

An alternator will charge around 13.5 to 14.8 volts. The only way to acurately check your charging system is with a meter.

The factory gauges are a good guess a best. Oil pressure for example is controlled by a switch. As long as there is enough pressure to close it then the gauge reads normal.

 

[TedJ]

Well, I got more then smoke, I caught it on fire and melted one of the leads...but still runs like a champ... goooo Harbor Freight!

Anyway, I'm pretty sure the stocker was a 95a, I don't think they would have put a 130a on my 93 sport, and I didn't measure the cases, but they looked pretty much the same.

Now would probably be a good time to stop plugging your leads into the amps jack and then connecting it to a voltage source.... before you end up with a pile of red goo that has a LCD sticking out of it :


The stockers are 95a, but there is no harm in going bigger (within reason, I wouldn't go over 130 without upgrading the wiring too). The main benefit is it does not have to work as hard, and puts out more power at lower speed, so you don't get dimming and voltage drop at idle with a bunch of stuff on. The large case series was never used on explorers (originally superduty trucks and such), but fits fine and is able to take more heat and load.

Just for a point of reference the original explorer alternator is the 3G series, small case.


By the way, that rebuild I mentioned in my last post just blew up yesterday. The bearings are toast and making squealing noises. Complete junk, it lasted 1.5 years. The original lasted 18 years and well over 150,000 miles. It's lifetime warranty, but how many times can I change it? My time is worth something too.

 

[shaggymane]

FWIW:

switching from apples to oranges for a minute, several years ago I decided to try the local rebuild shop when the starter on the Navajo went bad.
What's a typical rebuild on a starter?... brushes and bushings? Don't know what brushes cost but the last time i bought bushings, was like 2.35 or something. rhetorical question; what do the auto store rebuild places replace?
Anyway, for 65.00 I got the *rebuild* and a new armature cause the commutator was bad. When I went back, the guy made it a point to show me the old armature and tell me why the starter was acting the way it was, which i though was decent of him.

Not to long ago I took another starter in, went back a week later only to hear him say, "Can't condemn that starter, nothing wrong with it, your problem is somewhere else." How can ya not trust a guy like that?

So, I had good luck going that route and when I know my alt is bad I'm gonna go back to that guy.


Seems like I'm not getting something said...................when you can go back to the guy who did the rebuild there will be more accountability than run around (like auto parts stores can be notorious for)

yeah, i think that's all