I'm on my 3rd alternator in a year now and aM STARTING to wonder if my truck is somehow causing them to fail?? is this possible? ive been buying the rebuilds that autozone sells. they are alweays under warranty and i pay nothing to get a new one but this is getting very annoying. any help would be great guys!!!

 

belt may be too tight.
out of alignment w/other pulleys
poor quality alternators
you park in a high lightening strike zone

 

if its aftermarket, thats why. keep takin it back until you get a good one, if its from autozone or kragen.. lifetime warranty

 

Check the Voltage Regulator, I am not sure if it is built into the alternator in your vehicle or not. (Especially since I don't know what your vehicle is...)
I've blown up a few alternators that way.
Also - as has been mentioned already, check your belt, and pully alignment. Also check your ground points, and all wiring contacts.

Best of Luck.

 

Are you running a big stereo, light's or a winch?

 

check the ohm value on the wire going from the battery to the alternator and so on and see if they're spec (I think) and what they said above

 

no, stock truck.....95 toyota 4runner 3vz3 engine. nothing fancy just blowing alternators........will check the things said above tonight and let you know what i find out! thanks!

 

Couple more things. Check the wire from the Alt., make sure it's not chaffed or shorting. You could have a battery problem or a ground problem. You would probably have starting issues with the later. Like was said, it may just be Autozone.

 

bite the bullet.pay for a factory one & be done.sure the autozone is still under warranty & they replace them for free.but,what is your time worth to keep changin them out

 

Update. I didn't find a external voltage regulator so i assume its in the alternator?? Anyway i checked the belt had good tension, pulleys were in alignment to the naked eye. i took off the alternator and took to autozone and it passed there test. Talking to the guy he said it could still be bad as there test doesn't check for output of amps and voltage. he also told me he'd just exchange it regardless of the pass grade on it but he didn't have one. So they ordered one and at worst i can still exchange it tomorrow evening when they get it in. But he said to try checking the battery voltage when the truck was running so i did and its 14.4 which is ok i believe. 12.4 when not running. so i think battery is safe. I did however find that 2 of the 3 wires that plug into the back of alternator had a nick in the insulation so i taped them up and tried it but still same problem. also noticed the plastic connector that those wires go into and that plugs into the alternator is kinda cracked a few places like maybe somebody had a hard time disconnecting it once before and ,maybe used pliers on it or something. it looks intact but just cracked and smooshed a little. could this be causing it??????? can i check output voltage or amps when th truck is running or do i need to take it somewhere to put on a dyno? problem with that is when i tap the brakes or blinkers or the truck loses power and usually dies..........not very safe me thinks to drive it very far....!!!!

 

I'm not sure if it was a coincidence or not but I had the same problem. Was changing out alts and they kept dying. Then I finally got a new battery and a new alt and changed them out at the same time and never had a problem again. If your battery is worn then it will make your alt work harder, and vise-versa. Just my 2cents.

Jason

 

+1 Very possable

 

guess i could take it in and have it checked. it has water and it checks 12.4 and 14.4 not running/running respectively but it might be weak i guess. worth a shot. im running out of things to check!!!

 

Voltage at the battery does not tell the hole story. I would shut the truck off and measure the battery voltage. Then turn your lights on and see what is say. It should drop a bit but not much. Then watch and see how fast it starts to go down (if at all). It should be able to hold the same voltage with the lights on for quite a while. If the voltage slowly keeps dropping your battery is not in very good shape. This will cause your alternator to have to run everything when the truck is running. This is bad because the alternator will have a very high current running through it all the time which will heat it up and cause problems.

 

Bingo! This is the answer to your question. I had the EXACT same problem a few years ago....I just kept taking them back to autozone until I got a good one. I've had it ever since....probably 3 years now.

 

If all else fails, O'Reilly has ND alternators. I've never had a problem with those. Until the power steering pump started leaking. Caught on fire, even.

 

Flash, I did what you suggested. 12.4 volts with lights and engine off, then with engine off and lights on its 11.86/85. it stayed at that reading for as long as i held the leads on it(about 45 seconds). is that sufficient voltage with the lights on?

 

I would say thats about normal. Try taking a measurment and then leave the lights on for 10 min or so then take a reading again. If it has gone down I would get a new battery ( if it went down under 11.80 definatlly no good). A car battery should hold a steady voltage with a load on it for at least 10min, a new one should be able to go over 30 min without a drop.

If you are anywhere where it is cold and snowing like here (Toronto, Canada) Then you know a new battery is worth every penny. Don't cheap out either, a good battery will last longer then 2-3 crappy ones (stay away from Canadian Tire garbage).

 

My Vehicle: '94 Toyota Pickup 2wd 22re.
Why do these alternators fail w/o real warning? Would replacing all lights with LED help? I have a aftermarket 7" screen-DVD/stereo, but no KC lights etc. I believe our stock size is 60 Amp.
Can you all help with any updates on other higher Amp units fit?

Just over 2 years and less than 12k miles, the alternator catastrophically failed me on the Hollywood Freeway. It ran for 20 seconds after failure and then "DEAD". This was not a moment for me to jump up with my fist in the air singing "Toyota, I'm lovin' it" like the old commercials.

I did recently replace the 2 other belts (p/s, and A/C), but NOT the alternator one since that was also replaced 2 years ago. I also had a new cat-back (love the extra HP!) and was pushing the motor at WOT, so did I push it too hard?

Thanks Guys!

 

Probably bad alts in the first place.

No; Those do not load the alt that much. Good alternators would not break under those loads.
However, if using auxiliary lights, calculate total current draw and compare to alt capacity.

LOL! But not Toyota's fault. It's the fault of whoever remanufactured those alts.

Driving hard will not affect a good alternator, altho if there is anything mechanically wrong (i.e., misaligned mounting), you may damage your alt mechanically- but not electrically.