Alternator issue or something else?

[White87sr5]

Hey guys,

I have an 87' 4Runner with a fresh rebuilt 22re motor only 9500 miles on it. In the time since I rebuilt it I've gone through 3 alternators now and I'm starting to wonder if there's something I'm missing. The original one was bad so I got a new one from autozone. It was fine for probably 3-4 months then stopped pushing a charge. So I had it checked and it tested bad at Autozone. So I got it replaced and the new one held for probably 3 months then the same thing happened. But this time the test checked out on the machine but I replaced it anyway to be safe. The current alternator in my truck has been in there a month and the same problem is coming up. My stereo will cut in and out charge light comes on and now it's just totally dead won't even click or turn over. Oh and the battery i got back in April it's an interstate. Can I really be getting bad alternators or do I have another problem?

 

[89FourRunner]

Hey guys,

I have an 87' 4Runner with a fresh rebuilt 22re motor only 9500 miles on it. In the time since I rebuilt it I've gone through 3 alternators now and I'm starting to wonder if there's something I'm missing. The original one was bad so I got a new one from autozone. It was fine for probably 3-4 months then stopped pushing a charge. So I had it checked and it tested bad at Autozone. So I got it replaced and the new one held for probably 3 months then the same thing happened. But this time the test checked out on the machine but I replaced it anyway to be safe. The current alternator in my truck has been in there a month and the same problem is coming up. My stereo will cut in and out charge light comes on and now it's just totally dead won't even click or turn over. Oh and the battery i got back in April it's an interstate. Can I really be getting bad alternators or do I have another problem?

You very well may have another issues cooking these alternators, but I will tell you from experience -

Outside of this 89 4runner I had a 93 corolla commuter car, and the original factory toyota alternator died at around 150,000 miles. I replaced it with an autozone alternator, and had the exact same issues - the alternator lasted three to five months at a time - I exchanged three autozone alternators to no avail. I finally went to an alternator/starter rebuild guy and he told me that is typical with autozone replacements. I bought an OEM factory rebuilt one from him and it lasted until the car was sold at 270,000 miles or so.

There is a chance it is the quality of parts you are buying.

 

[Bad_Vision]

Sounds like cheap crappy autozone standard to me.
The alternator is internally regulated so only one external issue could be causing them to fail. If your getting voltage back through the alternator wiring from the circuit. (Super rare is a coil not insulated and discharging to the block causing the charge to travel through the negative cables into the alternator.

Simple testing with a volt meter will show back voltage just run the truck off the battery for a minute while you test the alternator wires for back flow.

 

[White87sr5]

So even though the alternator checks out in autozones testing machine they could still be bad? I don't even know what else to check. And I have checked everything with a volt meter it all looks good.

 

[flyinhawaiian01]

How much current load do you have on the vehicle? I big stereo system can and will burn up an alternator if its charging at full load all the time. Same goes for those who run linear amps for cb's and ham, they will toast an alternator pretty quick, don't ask me how I know this though...

How's the condition of your battery? If its got a dead cell, its possible to still start the truck, although it would turn pretty slow when starting, that too could push the alternator into a constant charge cycle where the battery accepts it but never actually charges up.

What part of the alternators is burning up? Is it the windings or the regulator? If the regulator is still good, I'd be suspect of a constant load in the truck, such as a bad battery. If its the regulator, that would tell me there's a heavy load on the system that's pulling more than the regulator is able to supply, such as an amp or amps that's pulling well over the alternator's max output, like 2 or 3 1000 watt amps (although it could be less than that I suppose).

 

[RAD4Runner]

Concur with above...
Find a friendly electrician with a clamp-on DC ammeter and use that to check current going through the "B" wire. That's the THICK WHITE wire that connects to SCREW Terminal on alt and to fuse network in fuse block, while everything is in full-blast, including stereo, amp, air-conditioning. All lights in high beam.

 

[White87sr5]

I checked my battery water level a month ago and it was a little low but no other issues with the battery I can tell. I don't know what part of the alternator is burning up. I just took them to autozone and had them tested on the machine there. I do have an aftermarket stereo with speakers, amp sub etc. but I do have the power regulator cord from Best Buy that connects to my battery that should manage the power level.

 

[flyinhawaiian01]

I've never heard of such a thing, "power regulator cord", and I used to own a car audio and alarm shop for several years! If you can, take a pic of this thing so I can figure out what it is! Inquiring minds wanna know!!!:shrug:

I doubt one amp will do it, but just to rule it out, how big is that amp?

I really think there's something else going on in your vehicle, and like Rad said, get someone to check the load on the system, that will tell you EXACTLY if there's a problem with the truck, or if these alternators you're getting are just shit.

 

[White87sr5]

It's a kenwood 600watt amp and an alpine 12in sub. I've ran this setup in another vehicle with no problems. I couldn't think of the name of the cord I'm talking about. It's a red cord the runs from my amp to my battery and it has a fuze inside it. It's supposed to prevent my amp from drawing too much power. Well I'm not sure where to go have an electrician check the load in my town I'll have to do some research.

 

[Ahlem]

Make sure your grounds are all in good shape, clean and attached properly.

 

[White87sr5]

I did just get the lc engineering header and I had a shop wire up my oxygen sensor since I changed from a single wire to a four wire sensor. Maybe they didn't ground it properly? It was a reputable shop in my area though.

 

[White87sr5]

Update: I removed and cleaned all my grounds used sand paper on all of them. Got another new alternator and replaced the connector that goes on top of the alternator. No charge light.

 

[placermike]

Use Deduction

Using a multi-meter, I would:

- Start vehicle, ensuring nothing is drawing power (Stereos, lights etc)
- Check the voltage output (13-16volts would be good)
-Turn your headlights on and note any drop in voltage.
- Turn something else on like a stereo and see what else changes.

A major drop will tell you were to look for the problem. The issue you have described has me tending to believe that there may be too much draw on power and the alternator is being overworked causing it to 'burn out'.

Hope that helps as a start. Electrical can be tricky to solve.

- Shorts burn out fuses and components
- Bad alternators allow batteries to drain.
- To much power draw can cause alternators to die prematurely.

There are other factors, but those are good premises to start with.

 

[RAD4Runner]

And I have checked everything with a volt meter it all looks good.

By good you mean ...?

What readings were you getting and at which points?

You sure you are getting full voltage to "IG" terminal?
You sure you are getting full voltage to "S" terminal?
Rule out wiring problem by connecting "IG" and "S" terminals directly to battery.

Charging System Explained here, with voltage readings to expect.

Checked this for corrosion?

 

[White87sr5]

I had 14volts coming off the alternator with no major drops with stereo on or headlights. No I haven't checked that for corrosion next time I get a chance I will. I've been driving it for two days now with no issues.