View Full Version : burnt $140 alternator.. ahhh ~~~ car

07-11-2008, 05:23 PM
im really pist right now, i installed a brand new ( rebuilt ) alternator from autozone yesterday, charged my battery to 12.6 volts, worked great drove today to work on the way back anti lock light came on and a howling sound from the engine, i knew it was going to die got me home , checked battery it was reading 8v.. this is my third burnt alternator, what could be burning them ??? the alternator was burning hot ??

the other two that got burnt were junkyards so thats why i bought new ..

pleaseee help

07-11-2008, 06:05 PM
Take it back you could have got a bad one. If it happens again you need to look for shorts or a bad battery, bad replacement battery terminals are almost always a problem.Never replace the terminal end replace the entire cable, you will save yourself a lotta greif.

07-11-2008, 06:23 PM
i think its a short , i forgot to add i installed a rebuilt one from a local shop, and burnt the voltage regulator, has new battery and new negative battery cable, the positive its kind of ugly but its not corroded or anything ?

could there be any fuse links messed up somewhere ??

Kurt K
07-12-2008, 12:07 AM
Sorry, but everyone I personally know that has tried an Autozone alternator in their SC has had to replace it at least once....one didn't even survive 20miles.

Spend the money on a Ford alternator.

That said, it does sound like there's an underlying problem

07-12-2008, 12:30 AM
Well I am on #3 now, the 2nd 4 weeks ago lasted 2 weeks then over volted to 19 volts & fried the batt. both were replaced under warranty now the alt requires 2200 rpms to
engage. so now I am stuck with it & it's lifetime, so I just get faster at
replacing it I guess. Oreilly's is the vendor & this last time they delivered it to me which I though was great. Wish I could refund & try elsewhere. ~~~!

07-12-2008, 02:14 AM
dam sucks, i got the alt out and tested ( im getting good at it took me 10 mins ) it sounded like crap on the test bench and it had a bad diode triode light, so im hoping the alt itself was bad, but im going to change positive battery cable just in case

07-14-2008, 09:08 PM
got the new alt in, charged my battery to 12.6 i let the car run for like 5 minutes , voltage was 14.3-14.5 but the alternator got hot quicker than the thermostat housing tube. so i shut her off.

i think my battery might be bad i used it for 2 years on my crown vic without problems but might have gone bad.

i got a spare battery im going to try and see. alternator getting hot quick means that the battery is not working properly making the alt work harder ???

07-14-2008, 09:11 PM
or there is a short in the battery itself.


07-14-2008, 09:18 PM
so it should be battery related ?? i checked the alternator harness and i get continuity everywhere.

im also trying to install a voltage gauge to atleast get a heads up on when to hurry home before it dies. where should i tap the positive to ?

btw i just paid my $15 forum sign up.:D

07-15-2008, 11:52 AM
Start pulling fuses and see if you can at least isolate the circuit. You've got a serious shorted wire somewhere.. I'm surprised your battery is surviving.

07-15-2008, 11:59 AM
so it should be battery related ?? i checked the alternator harness and i get continuity everywhere.

im also trying to install a voltage gauge to atleast get a heads up on when to hurry home before it dies. where should i tap the positive to ?

btw i just paid my $15 forum sign up.:DCheck the starter cable.. its an always hot lead to the starter motor. The starter itself could have a short as well.

Easiest place to hook up your voltage tap is to the fuse panel under the dash... use as small of a guage wire as you can and loop it around one of the fuse tabs.. don't push it in all the way or you'll have problems later on. Just enough to make and keep contact.

07-15-2008, 12:09 PM
I bought a duracrap and it was doa. It's always better to get your factory alt rebuilt...even if you spend a little extra going that route.

07-15-2008, 12:45 PM
I had an AZ alt that made it to the end of my street. The 2nd one lasted about 400 miles...

07-15-2008, 12:48 PM
Before you start the car again, I would have the battery checked. Autozone should be able to verify if your battery is shorted. If you had a shorted wire, that 160 amp alternator would fry the insulation on the wires and you would have smoke or sparks. The battery is the only thing that would draw a lot of current with no visible signs of smoking or melting anything.


07-15-2008, 09:16 PM
yep, check the battery

I bought 3 Autozone alternators and all of them were or went bad within a day. When I went the fourth time to exchange it I had the guy take it out the box and test it right there before I even walked out....the thing was dead rigth out the box. I got my money back and ended up buying a brand new motorcraft unit from rock auto.

07-15-2008, 10:24 PM
For some reason, the generic rebuilders just don't do a good job, thus autozone and checker, and all them guys just can't do it right. I'd be curious if the NEW off brand alts are any good. Best bet is to have your alternator rebuilt by someone that rebuilts electric motors, starters, alts, big motors. They tend to take their job serious, and will take the time to do it right. Just don't be in a hurry and it'll turn out well.

A bad battery can test good voltage, but once a load is placed on it, a internal short can be exposed which causes an alt to see it needs to charge and feed the short, quickly burning up.

The type of housing and rating on the components doesn't have sufficient beefiness to deal with constant charging. It'll burn up pretty fast.

07-16-2008, 12:28 AM
when i got the new alt back i had him test it in front of me. also im worried of a short because one of the alternators that was there was overcharging and smoke came out of the alt cable that goes to the starter solenoid. but like i said the harness has good continuity.

im going to take the battery to autozone tomorrow to get it tested. thanks for the suggestions guys.

07-16-2008, 12:58 AM
Having replaced my alternator about a month and a half ago I would say that auto zone alternators are getting a bad rep when it's not all bad. I tried to go the rebuild route but the alternator is not common so the shops don't have the parts on hand. SC is my daily so I didn't have the time to wait until the parts came in. Still would have only been 40 bucks cheaper without a lifetime warranty though.

I did a little searching and the biggest piece of info I found was that under no circumstances should you ever charge a totally dead battery with an alternator (especially a rebuilt imported alt) unless you have no choice. It's too much of a strain on the diodes/regulator and it will cause them to overheat and likely shorten their life, maybe killing it. Use a battery charger if possible before starting her up.

Oh and it's worth mentioning that as I was searching either these forums or TCCOA looking for another option I kept coming across the same guy badmouthing the autozone alternators in like 5 threads, and then finally found one where he admitted that it was a dirty contact problem at the alternator connector that was causing them to seem faulty. Mine has had absolutely zero probs since I swapped it in. Maybe I'm just lucky, maybe not.

07-19-2008, 05:34 PM
got battery tested and its good !

replaced positive battery cable and the alternator still gets really hot plus it kind of has a grinding noise as its running, im just waiting for this one to burn again so i could get another one :rolleyes:., i temporarily installed a volt meter gauge to tell me when it goes