Hi guys,

My beater 1990 SCCA rallycross car is killing alternators.

The original alternator died 3 months ago - just stopped charging altogether. It had ~200,000 miles on it, so no surprise there.

So, I went to autozone and bought a new 1.6L alternator. It was in the car for about a month, and was working fine. Then, I was dicking around with the software in my ECU, and needed to reset it while driving. So, I was cruising at 50mph in 5th gear, and just keyed off, then keyed back on. A key cycle with the engine spinning at 2500rpm. Once keyed on, the charging light came on, and I verified that the battery voltage was now at 19V! Crap!! I was only 5 minutes from home, so kept going. By the time I got home, the alternator had died completely, and was now not charging at all (battery voltage at 11.8V).

So, I decided to never do that again (key cycle with engine running), and got a free replacement from autozone. This new replacement was in the car for about a month until this weekend when I had an SCCA rallycross race. The course was really quite bumpy, bumpy enough to toss the trans out of second gear if not manually held in place (another problem I'm looking for some advice on). Maybe the bumpiness killed the alternator??

I'm getting another free replacement from autozone. What should I be looking for in order to prevent this from happening again?

Possible causes:
-A single battery cell is going open circuit when vibrated? It checked out fine when static, and autozone claims it is fine.
-Bad grounds - checked the normal grounds at the trunk, on the PPF, and between the cylinder head and chassis - they are all fine.
-Wire between the alternator and the fusebox - I checked this, and it looks fine, not overheated or corroded. Did a resistance check, and it is at 0 ohms.
-I see some others have suggested running a dedicated cable from the alternator case to chassis ground. I guess I could try this.
-The car does not have a radio, and is otherwise a completely stock electrical system.
-The battery does not drain down when the car sits for a week, so no errant current draw.
-Autozone alternators suck donkey *****? Should I just buy a used OEM unit?

Any other ideas?

 

Stop buying/replacing parts store alternators. If you search miata.net, there are quite a few stories like this. AZ and similar rebuilds are crap.

Get your original rebuilt by a reputable shop that specializes in that. I paid just slightly more than an auto parts store alternator to get this done, and my alternator alternators like an alternator should.

 

it takes about 4-5 alternators to get a good one when buying "refurbished" units from autozone or advance auto.

also, with regards to buying from autozone: who in their right mind would shop there with advance autos 30% coupon codes?

 

Where does one find these magic 30% coupons? I just might ask for a refund from autozone and go with a shitty advance alternator instead.

Also, I just checked the Mazdaspeed Motorsports price for an alternator: $125 Maybe I'll get a refund from Autozone, and just buy a rebuilt OEM from Mazda.

 

Parts store rebuilt alternators are your issue. Never leave with one again without making them bench test it first.

And even then, just expect it to fail every 3 months.


I went through EVERY alternator for a 90 MX6 about a year and a half ago in the entire Indianapolis metro area through Autozone trying to get a good replacement. In 2 days. Finally got one that seemed to work ok from Advance. (They had two. One tested bad, the other passed barely, i had to take it.) I'm sure it'll fail within 10k miles.

Advance codes: TRT30 for 30% off. A124 for a tiered discount.

 

QFT.

 

Just for reference, I had your same exact problem, except on my NB. I went through many diffferent brands of alternators from Autozone/Oreillly/Advance. I even got the stock unit rebuilt by a reputable shop, still didn't work. Pretty sure the parts store alternators repair process they use is 1)take apart a bad alternator, 2)stare at it, 3) Replace the pulley and other things that do not actually break, 4)clean and paint parts, 5)Resell. I really do not know how they can botch 90% of their refurbished alternators if they actually repaired them.

The fix was buying a used alternator on ebay with 60k miles. Has been going strong for over a year now.

 

Related issue: starters are no better than alternators when it comes to these places. Had to put 2 on the wife's tracker before finally buying a low mile used OEM one from ebay.

 

went through three vato zone alternators. 2x that just wouldn't pump any juice and one that did work but made the worst bearing/bushing noise ever. Had my original rebuilt by a local shop that came recommended (thank god i didn't turn it in for core) and has been working like a champion ever since.

**** vatozone (odeleh homes)

 

When I worked at Checkers (formerly Checker's/Shuck's/Kragen, now Oh-oh-oh-O'reilly) we sold A1-Cardone remans, and while I worked there I didn't see many returns. Our rep told us that every wear item was replaced on their remans, not like other companies "refurbs" where they replace only the part that failed. But, being from a salesman, take that with a grain of salt.

The local alternator rebuilder here uses super cheap Chinese parts, so it's even more hit or miss than the parts store, plus you wind up waiting for warranty work since someone actually has to work on it.

We have a Mitsubishi alternator. I found a source for the rebuild parts a while back, if anyone is adventurous.

 

This Place:

Alternator & Starter Parts Wholesale

Has every part you need to rebuild your starter and alternator.

 

A lifetime replacement warranty on an alternator guarantees a lifetime of replacing alternators.

When the alternator failed in my 2001, I got an alternator from a 2004 from a wrecking yard. That was three years ago and it is still working. One advantage of getting it from a yard: the pulley is still on it. I kept the old one and when the current one croaks, I will get it rebuilt. The old one definitely needs bearings and it looks like the series pass transistor is shorted internally since it puts out over 15 volts.

 

This is why they're garbage in the first place.

Millenia alternator swap gets you a Denso unit.

 

So all I have to do to run a Milennia alternator is add a +12 sense wire to my harness for the regulator?

 

Believe so. Haven't looked into it for the Miata, but that's what it took for the MX6. I don't know how it works for Miatas.