For about a year now i have had four new alternators put on my 02 SS/Z28 Camaro. I cannot figure out the issue that is causing them to fail and it only happens when I go w.o.t. The volt gauge drops into the red zone and i am able to drive it for a little while after it fails before the car dies I've put a bigger positive battery cable and put a bigger than stock alt. on as well and apparetly that did not fix it. It has a brand new battery. Any input would be very helpful.

 

What brand and type are you using? How are you using the car? It's not uncommon for reman or lesser quality alternators to be bad out of the box. (Over and over and over again.)

 

I was having an issue with alternator failures. I was on my 4th alternator then someone suggested that I find a local rebuilder, sometimes hard to find today being that most people are just "parts changers". I took my OEM to this guy and he showed me the difference internally between the OEM and the CHEAP Chinese made parts made today. He rebuilt my alternator and my issue went away. If you dont have an OEM you could always go to the junk yard.

 

I am definitely familiar with this exact situation.

The "local rebuilder" option mentioned above is a good one (if you have someone local who is good). Otherwise, I'd recommend sticking with either GM or Powermaster (Powermaster is the only brand other than OEM with which I've ever had great results).

 

What is the upper engine RPM range you are hitting when the voltage problems occur? It could be a combination of over spinning the alternator shaft and/or poor internal components not rated for high shaft RPMs. The CS130 was a poor alternator design because of all the compromises used to shrink the physical size. The CS130D redesign that happened to come in the 98-02 F-bodies was a nice improvement except 1) it still used the stacked rectifier design which is prone to overheating and electrical interference and 2) the low mounting location is not a good environment for an alternator due to the risk for fluid intrusion into the case.

After the CS130D, GM deployed vehicles with the AD230, DR44G & then finally the AD244 .The best upgrade is the AD244 alternator; it does weigh a few pounds more, and has a larger case which might require loosening other components (such as a larger than stock front sway bar) to R&R it. But the mounting location can still cause electrical gremlins from fluid intrusion. These cars came from the factory with a rubber splash guard between the driver wheel well and the alternator location, but often that splash guard is damaged or lost when shops are working on other parts in the vicinity. There are common alternator relocation brackets that move the alternator to the passenger head and remove the tensioner pulley, or another variant that can move it to the driver side near the PS pump. If you don't have access to the factory splash guard or the relocation is not desirable, perhaps a custom splash guard could be fabricated by a local shop. Also, because the spinning components inside the larger 244 case will have slightly more mass, the smaller CS130D/AD230 case could be more reliable for vehicles which spend a lot of time in the upper engine RPMs (say on open track days on a road course). You should also consider a "Big3" or "Big4" charging wire upgrade; I went with the "LS1 H/O" kit from Innovative Wiring years ago.

Many folks just upgrade to the AD244 and call it a day without touching the alternator pulley. But you can also partially circumvent the over spinning by using a slightly larger alternator pulley which reduces the alternator shaft RPMs at the same engine RPMs. The larger pulley will cause your engine to charge slightly worse at idle (unless you bump up the engine idle RPM to compensate) and it'll cause the alternator to not spin as fast at the upper engine RPMs (which should improve the life of the alternator). But the larger pulley won't address the CS130/CS130D rectifier design weaknesses. You generally want the alternator shaft RPM to be at least 1800 at idle and no higher than 16000-18000 continuous at max engine RPMs. The factory setup was:

Engine RPM: 800
Alternator pulley: 2 7/16"
Crank pulley: 7 10/16"
Alternator shaft RPM at idle: 2503
Alternator RPM at 6000 engine RPM: 18,769

I had my car tuned to idle at 850 RPM because of the camshaft, but I still had low voltage at WOT above 5000RPM with multiple locally purchased alternators. I had the same problem as you... alternator behaving fine, then I take a couple of spirited runs to redline for tuning... then the alternator starts misbehaving. I finally tried a 2 3/4" alternator pulley in conjunction with my ATI crank pulley and a locally rebuilt alternator, which changed my numbers to this:

Engine RPM: 850
Alternator pulley: 2.75"
Crank 7.53"
Alternator shaft RPM at idle: 2318
Alternator shaft RPM at 6000 engine RPM: 16429

The upper RPM issues disappeared. However, I do a lot of driving around town, so I spend a lot of time idling, and thus my charging decreased at idle. So I changed my engine idle RPM to put me back at 2500 alternator shaft RPMs to restore OEM charging rate.

2.75 / 7.53 * 2503 = ~914, so I set my idle to 915.

I recently ordered and am awaiting delivery of a new 'hybrid' CS130D/AD230 220A@14.8V design because I wanted the potential increased reliability for open track day use. It includes a CS130D front case half, an AD230 rear case half, the heavy duty AD244 rectifier, and my preferred 2.75" alternator pulley. I already have a catch can in the passenger head location and I'm not convinced driver relocation will fit so I'm hoping I'll have good luck in the OEM mounting location.

Hope that helps.

 

Thank you for your post. You have some well constructed points and they were great to digest vs. the common "bigger is better" logic.

 

In my experience it's better to have a local shop fix the alternator instead of replacing it with an auto parts store one. The Best replacement if required being another OEM unit. The couple of times I've had to get an auto parts store replacement here was my experience:

Autozone - sells junk alternators in my experience. They seldom last a year of normal use. Autozone Duralast Gold is an exception being made with new parts. I ran one for 200,000 miles and ten years with no issues. It was replaced with another Duralast Gold that hasn't had an issue in 100,000 miles.

NAPA -had quality OEM alternator

My 91 RS had an alternator issue when the LS swap was done. It needed a new voltage regulator as Jim Muller mentioned above. No issues since the rebuild repair.

My TA had the OEM alternator with no issues for 18 years and 164,000 miles. I think the ATI 10% under drive helped protect it. Idle speed was 850-900 rpm with the heads and cam package.

Sometimes other things can hurt accessory performance like a weak tensioner or wrong size belt or misalignment.

 

I bought a Delphi and my charging issue went away.

 

My stock alternator failed at 161k a few weeks ago. I had it towed to my buddy's shop and sent him this thread below. But before I knew it, he threw a reman on it. I can already tell from the gauge that it's not charging like the stocker did.

The post above is informative, but most of us don't know the part numbers. A lot of guys have had success with the 145a truck alternator:

https://ls1tech.com/forums/generatio...failure-s.html

 

I had a local parts house years ago have 5 bad out of the box alternators for my 93 k5. Stock one failed, put a reman on it, no charge. Bench tested it and the grommet at the parts store said I must of installed it wrong and that's why it wasn't working. I'd used this supplier for years as I was a tech at a local shop, went to the local warehouse and talked with the manager I knew, we pulled all 6 he had and bench tested them, only 1 tested good. He defected out the other 5 and I installed that 6th one, was working like a champ 3 years 40k miles later when I sold the truck. That parts store has now been franchised by NAPA so the quality has gone up, but still had issue with NAPA re man items. I've got a radiator and alternator rebuild shop near me that I take my personal stuff too if need be.