Brand new alternator dies after 3 months???

Stangswagalicious

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Hey friends. Got another issue i cant seem to figure out.

Not to long ago i was having charging issues on my 95 gt. After lots of digging, turns out the field wire wasnt getting proper voltage. I never did figure out why the field wire wasnt putting out the right voltage. Mainly because after i started digging into it, there could be multiple issues (including the gauge cluster) that i just didnt feel like chasing down. Once i figured this out, i got a new alternator, spliced the field wire into the positive terminal on the ignition coil and boom. 13.5-14 volts consistently.

Shortly after i had to replace the harmonic balancer. While i was there, i went ahead and pulled the trigger on some underdrive pulleys. I was worried about the alternator so i left the factory pulley on the alternator and just replaced crank pulley and waterpump pulley. As predicted, the alternator struggled to keep up at idle but even the slightest bump in revs and it charged just fine.

Understanding all of this, i clocked out of work friday and started the car. I sat there for a good 20-30 min on the phone with the ac on before i left work. Once i left, i noticed the alternator wasnt picking up voltage as quickly as it normally does. Shortly after i hit the road it quit charging all together and now im running off battery power. Unfortunately for me, my drive home is about 30 min from work and i barely made it home. When i parked, volt meter was showing 8 volts. Im honestly not even sure how i made it home... and it definately smelled like burnt electrics when i popped the hood

Lastly, as soon as i got home i unplugged the battery and put it on a trickle charger. Took 2 days to charge. Monday morning i decided to start trouble shooting. I plugged the freshly charged battery back in and as soon as i did the alternator started making these faint crackli g noises. And it got hot. Super hot. Almost to hot to touch after being plugged in for maybe 30 seconds. Something has shorted out...

I know im going to catch some shit for my hot wired field wire. But unless someone has a better spot to run it to, its worked fine for months. Wtf happened here? Did i idle for to long and max out field for to long before i left work and it over heated? Junk alternator? Are there any alternator upgrades available? Im sooo sick of working on this car just to be reliable. Iv seen the 3g alternator upgrades but that seems to be a fox thing.

Any input at all helps. I appreciate you all
 

ttocs

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Where did you get the alt? I got one off of ebay that I got a great deal on (10+ years ago) and it only lasted 4 months. But even with that I have said for years now UDP's are great on racecars, not on streetcars and because they kill the alt. You slowed down how fast it turns which does two things - limits how much current it can make as well as limit how well it cools itself as it is designed to pull air through it to cool. What you have not done is reduce the load on the alt. All of this = more heat = bad alt/voltage regulator. They are not a problem on racecars because they stay up on the rpm range where it will make enough current.
 

white95

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This is going to be fun.

BDCE0A51-A159-4C6B-B485-9FC16D567D1D.gif

Turn the key on (KO) Look at the dash cluster. Is the battery light on?

Yes? Good.

No?

Well, that means:

1) The bulb is bad

2) The resistor is bad

3) There is a break in the wiring between the regulator plug and the dash cluster

The resistor is in place to allow turn on power to reach the alternator in the event the bulb fails. You should read 12v with the key on at the terminal with the light green/red wire at the alternator.

Check this and report back.
 

tvsn95

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In the for what its worth
I have Had BIG problems with Alt's .not uncommon to get a few weeks out of one these days. Mostly regulator failures even though I did sling one apart last month LOL.
you can ground the back of the reg and it should go wide open,, if not its the regulator that has failed.
I was on the Powertour this year and saw a couple of guys changing out Alt's . seems they were all pretty new ones already, just ain't worth a dam.
I swear the ford stuff is worse that the GM.
 

dwcopple

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I think my LMR one is a pile too. Gotta wait until my car is back though to be sure
 

RAU03MACH

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I remember when alternators would last at least 7 years
No problems

Now when your battery goes dead it drags the alternator with it
 

Rtfm

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The rebuilt alternators are pure crap these days. You have several options, though. Buy a new one from rock auto.com. Some new ones are about the same price as a rebuild. If your old one has a serviceable rotor and stator (check the diodes - a bad diode will reduce output), then you can get a rebuild kit for around $30 including bearings and a new regulator.
If you have a burned stator coil or rotor, then you can get a replacement. Using decent parts, you will have a reliable alternator.
Rebuilderinabox.com is a good source for a higher output stator, and the rebuild kit with regulator is included. About $115 IIRC.
Alternator parts.com also has the rotor if required. Usually the rotor is ok, though.
I am assuming this is the 3G alternator.
Building your own is much better than trying multiple parts store rebuilds.
 

ttocs

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The one I got on ebay was supposed to be a high output alt. When it burned up I took it to a local alt/starter shop and they took it apart and said that everything in it was set up for HO except the voltage regulator was still only ready for mickey mouse. There really isn't a lot of parts in an alternator even if you count the diodes in the bridge rectifier.
 
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Stangswagalicious

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Where did you get the alt? I got one off of ebay that I got a great deal on (10+ years ago) and it only lasted 4 months. But even with that I have said for years now UDP's are great on racecars, not on streetcars and because they kill the alt. You slowed down how fast it turns which does two things - limits how much current it can make as well as limit how well it cools itself as it is designed to pull air through it to cool. What you have not done is reduce the load on the alt. All of this = more heat = bad alt/voltage regulator. They are not a problem on racecars because they stay up on the rpm range where it will make enough current.
I bought it at my local parts stop. It is under warranty so i should be able to get another one but they have to order it. There is no extra electrical accessories on the car. So like no subs or lights or anything. But, my thought process was if at idle, it cant produce the voltage it wants, it will max out the field to try n catch up. Which probably isnt normal for alternators. So im wondering if having the field maxed for so lo g over heated it. Otherwise i have no clue. I have a feeling these remanufactured parts are junk anymore
 
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Stangswagalicious

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White, my field wire is no longer hooked up to its normal wire. I hot wired it to the ignition coil. I know i know its probably not the best idea but it worked fi e for months. However i de remember doing this test before i hot wired it and i believe it passed.
 
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Stangswagalicious

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Problem is now when i plug the battery up the alternator crackles and gets real hot real quick. I dont think its a regulator fail. I thi k something shorted out in the alternator
In the for what its worth
I have Had BIG problems with Alt's .not uncommon to get a few weeks out of one these days. Mostly regulator failures even though I did sling one apart last month LOL.
you can ground the back of the reg and it should go wide open,, if not its the regulator that has failed.
I was on the Powertour this year and saw a couple of guys changing out Alt's . seems they were all pretty new ones already, just ain't worth a dam.
I swear the ford stuff is worse that the GM.
I
 

lwarrior1016

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I ran my 2v for many thousand miles with the green wire on a regular switched 12v source. There were no problems with it. I think you just have a junk alternator. Or maybe your ground path for the alternator isn’t clean
 
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Stangswagalicious

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The rebuilt alternators are pure crap these days. You have several options, though. Buy a new one from rock auto.com. Some new ones are about the same price as a rebuild. If your old one has a serviceable rotor and stator (check the diodes - a bad diode will reduce output), then you can get a rebuild kit for around $30 including bearings and a new regulator.
If you have a burned stator coil or rotor, then you can get a replacement. Using decent parts, you will have a reliable alternator.
Rebuilderinabox.com is a good source for a higher output stator, and the rebuild kit with regulator is included. About $115 IIRC.
Alternator parts.com also has the rotor if required. Usually the rotor is ok, though.
I am assuming this is the 3G alternator.
Building your own is much better than trying multiple parts store rebuilds.
How do i know its the 3g alternator?? I know it doesnt look like the fox alternator with the exposed fan... i just got a factory alternator from my local parts stop. It has a warranty so im going to get a free new one but man... if i have to replace this turd again im just going to get my money back
 

ttocs

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like I said above when you slow it down you limit how well it can cool itself
How do i know its the 3g alternator?? I know it doesnt look like the fox alternator with the exposed fan... i just got a factory alternator from my local parts stop. It has a warranty so im going to get a free new one but man... if i have to replace this turd again im just going to get my money back
if you have to replace it again, take off the udp's.
 

ttocs

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I have never found under drive pulley's to be worth the headache...
I have heard of some guys that do road racing that needed them just because they kept the rpms up high enough for long enough that it would cause charging problems and needed to slow the alt down a tad to get it to work correctly. As long as you keep the rpms up its not such a problem but just like this one started with the car idling for 20 mins and then you get problems. I will agree with you as I was happy that I got mine used and kept my stockers as I was able to sell the UDP's for what I had into them and the only money I was out was the alt.
 

Rtfm

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For a 95, it should be a 3G alternator. There are two output ratings, 90 and 130 amps, so make sure yours is a 130 amp. 130 amp is a larger case.
Ditch the under drive pulleys. They are causing nothing but trouble and you need the rpm for a street car.
The crackling when you hook up power means the diodes and/or regulator are shot. Bad stator diodes will pass a lot of current into the stator coil and run down the battery. Ford 3G alternators are type A regulation, so they have a hot field at all times. The regulator is after the field coil and sends current to ground to power the field and regulate.
Looks like your alternator is toast and would require a complete rebuild of the internals, except for possibly the rotor. It only passes about 3 amps full field.
 

LEGALLYFAST

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If you have a good alternator repair shop near you I would just take it to them and let them rebuild it. Some shops build quality rebuilds. I take my stuff to Ace Alternators in Yucca Valley, CA. They have rebuilt everything for all cars and it runs for years after that. I don’t live there anymore, but I still deal with them if I need anything done.
 

ttocs

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I think you will get 10x better service from your local alt shop than you will anything over the counter/big box or online sales. Even in a small indiana town I was able to find an alternator/starter shop.
 

sn95slobrah

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This happened to me a few weeks ago. I made a thread about it. Turned out to be the voltage regulator…. Am I reading correct that revving the engine will cause this problem ? Because the day it happened I was getting on it pretty good
 

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