Bad alternator?

Rerun

Founding Member
Mar 31, 2002
312
0
16
South Bay, California
So my battery died the other day, starter would just click when they key was turned. I took the battery out took it to autozone and the test read bad battery. The guy said he'd just put it on the trickle charger for 4 hours and see what it tested at when he was done. So, I came back later, retested the battery, it came out with a good test. Soooo, I brought it home put it in the car and everything seemed to work fine.

So today, I'm on my way home from work and I'm watching the voltage guage, it was at the R on Normal pretty much all the way home, but then it slowly started dropping. By the time I got home to my place it was below the A. I'm trying to figure out if I need a new altenator or a new battery.

I do have under-drive pullies, and I don't think the alternator is stock.

Any help?

Thanks fellas.
 
Alrighty, so I went out and ran some tests with my voltmeter. Prior to starting the car I put the meter on the battery terminals, got a reading of 11.75 or so. So I went to go start the car and the car sounded like the battery was low. I went and retested the the battery terminals, got a reading of like 10.45, went and tested the alternator point same reading, 10.45. I shut off the car, when to try and kick it over again and the starter just clicked. Went and tested the terminals again I'm getting a 9.85 on both the terminals and the alternator point.

So, battery or alternator?
 
It sounds like your regulator is bad. I had the exact same problem. Alterstart has some very good quality 160 amp 3g alternators on ebay. I have one and it works great. Go check them out.
 
good call. you can have it bench tested first, but why. short of that, if you have a charger, charge the battery overnight. check the voltage at the battery, with the car off. then with it idling (as you did before). you should really see a bigger difference. right now, your batt voltage is low, like your alt output. charge the batt and note the voltage. then start the car and put the DMM on the alt hot wire - it will probably read a couple volts lower than your battery voltage.

but it certainly sounds like the alt is bad. you can also lose a diode in it - it wont charge (and can discharge the system). there is a fusible link that has to do with voltage regulation - might be worth a quick check to be sure it did not burn.

the PA stuff is top notch (from reading a million threads). Alterstart is supposed to be good too.
alternatively, you can use an alt from a 94-95 stang. i might go that route when the time comes. you will need to do the wiring upgrade. get a kit or piece it together (stereo shops have the stuff).

here is a post from Jrichker - the second group of links has some good info if you want to do the upgrade.

http://forums.stangnet.com/showpost.php?p=4000541&postcount=4

good luck.
 
K, so I went to yank the alternator off, and noticed that the mounting bracket has been cut like per the instructions of a 3G installation, so maybe it already has a 3G in it.

I ****ed up my hand trying to loosen the belt tensioner, and still didn't get it loose.

So I guess I should still take it in to get tested.
 
the tensioner bolt does not break loose you just push up with the ratchet and it will put slack on the belt and then just pull it off, i just got done with my alternator to, i had the same problem, but i cant tell if it fixed it because my battery is dead. but it sounds like your alternator is shot.
 
Rerun said:
I'm like martha stewert out there trying to loosen the bolt on the ****ing tensioner.

I'm a ****ing douche, someone come take my car, please.

I'll give ya $100 for the car and that includes the shipping
:D

Yeah they are kinda a pain to move at the start. The wrench I used dug into my hand untill I was able to clear the fan houseing. Strong will bastards lol
 
Alright, removed the alternator, finally. Took it to a shop and had it tested, guy says it's charging fine. So then I thought it must be the battery. I go and buy a new battery, and come home.

Jack the alternator back in, put the battery in, and the volt guage reads like it did when I got the car, awesome right? So I try the test of starting the car, taking off the positive cable and yay it still ran; I'm a happy camper.

But wait, I take it for a test spin, and everything is fine until the car gets a little warm. Then I notice the volt guage drops way down, **** I say. So I jam home, put the voltmeter on the terminals, now it's only reading 12 instead of 14! Take the positive terminal off and the car dies. I do infact have a 3G alternator, I'm wondering if it's deciding to work when it wants too or if I have some sort of electrical problem. Any help would be appreciated, I'm at my wits end with this ****er.

Oh, yeah, should I mention this all started to happen after the install of my autometer guages. All the wiring goes to the wireharnesses behind the speedometer, except for the air/fuel ratio signal wire which goes to the signal wire on my O2 sensor. Could this be an issue? Or is it totally unrelated.
 
Rerun said:
Oh, yeah, should I mention this all started to happen after the install of my autometer guages. All the wiring goes to the wireharnesses behind the speedometer, except for the air/fuel ratio signal wire which goes to the signal wire on my O2 sensor. Could this be an issue? Or is it totally unrelated.

LOL yeah you found your problem right there, the altenater is wired up where if you don't have the stock charging light it won't charge I had a similar problem after I installed my autometer's (well actually mine was that I tried an LED and it won't work") You have 2 choices, you can rewire it where you don't need the light or you can simply rewire the light.
 
gopher_6_9 said:
LOL yeah you found your problem right there, the altenater is wired up where if you don't have the stock charging light it won't charge I had a similar problem after I installed my autometer's (well actually mine was that I tried an LED and it won't work") You have 2 choices, you can rewire it where you don't need the light or you can simply rewire the light.


I just installed 2 guages to the a-pillar, would this still do with what you're speaking of? I don't quite understand what you mean.
 
i think what he means is that voltage regulation goes through the harness behind the cluster.

i would take the car to be tested at the parts store when you have it hot and not charging. also check the voltage at the alt itself, and again at the battery. if your cable is fried, it will show a nice voltage drop. as Michael says, "dont let the smoke out" - not what he was referring to, but same idea. basically when the alt to solenoid cable gets hot, the resistance shoots throught the roof.

good luck. congrats on having a 3g already - a nice surprise. :)
 
Well, so I got tired of ****ing with it, so I took it to Autozone and Kragen and both said the thing is bad, like real bad.

So, I'm going to bite the bullet and get another 3G. I don't think it's the wiring every time i tested the alternator hookup and the battery terminal the voltage was about the same, the alternator's was just a tad higher but not much at all. I think it's just the alternator. :/
 
yep, sounds like it. i was afraid of that, but wanted to toss out a few ideas - it would suck to replace the alt and have it still not charge right.

good luck with it.