Alternator keeps failing!

1992 Buick Park Ave. I have replaced the alt 3 times and the batt as well. Both keep dying. The batt is dying cause of the alt, that I know for sure. The wiring is good. The volt gauge shows about 10 to 11 volts when under a load like w/ ac or lights on. The alt works fine for about 2 weeks, and then it starts making a slight noise, and thats when I have volt prob! When I turn on power in the car, e.g. power seat - etc., volt drops! Especially when the lights, or ac is on! It has 127k miles on it, and has been taken care of. The crank sensor is new, there are no codes, plugs, wires are new! No fuses are blowing. I have checked all visible grounds and are good. I know alot about this car from inside to out but this is a challenge that is kickin my butt! Please help!!! Rob :confused:

Where are you getting these alternators? Auto Zone?

i would just get a delco from the factory. its not something most people do, but apparently the remaned ones from auto parts places are really starting to suck.

Ok, point taken! That got me thinkin - What amperage do I need, 105 or 140? I have a 105 amp in it now because of no heated windshield, the 140 amp was for the heated windshield, which I don't have. Now I checked into acdelco and they have a 140 amp with no mention of heated windshield. Not one option has been spared on this car except the heated windshield, wouldn't it make sense to have a 140 amp anyways because of all the options? Thanks again.

sorry - left this out. The diods are shot when tested after being on the car - is it because of a cheap alt, or not the proper amperage? thanks

The diodes can blow due to an overload. I have a friend that has a shop rebuilding starters and alts and he always uses a heavy duty diode pack when rebuilding GM alts. I forgot exactly why, but he said something about gel filled diodes withstanding the heat and load better. He has modified about 10 for me and I have never had another diode failure with his modification.
He also said that the 105 amp alts have a hard time staying alive on a car with a lot of accessories. Another thing to consider is, if the battery is low; charge it up with a home battery charger instead of the alt. If your battery discharges to the point that you need to jump the car to start, you could melt the diodes.
:newburn:

One other thing, do not skimp when buying a battery for these cars. I use the one rated for the heated windshield (900CCA) which has a larger frame and extended drain time. It fills the tray up, but fits nicely. I run the 140 amp alt also.

Thats the answer I was looking for, it just makes sense! Thanks for the extra info on the diode packs, and the battery! Going to purchase both - alt and batt, now I don't ask alot of questions at the parts stores because most of the time their full of it - so - do I need to take the new alt to have the gel diode pack installed at alt shop or can I buy it with it already installed? Thanks again for your time!

You could call an alt shop and see if they know what we are talking about. The guy I know has been doing this for quite a few years and has learned a lot of "tricks" on how to do things. I am sure everyone is not as knowledgeable as he is. Try a Delco alt along with the Energizer battery (Wal Mart) as described above, and see what kind of luck you have. Be sure the alt has a lifetime warrantee.

Thank you! I'm on a mission! I'll get back with you on the progress/outcome!

That Buick didn't show up last time I was on! It's beautiful! Spittin image of mine! Ok, still looking into the gel diode pack, but I did get an acdelco alt., and a 935 cca battery! I went ahead and put them in so the ac comp. doesn't starve of juice! It's just flawless! Volt gauge barely moves when putting my fingers on as many buttons as I could push! AC-lights-seats-inside lights-windows-etc.-etc.! I got more power in accel., engine runs smoother, trans. shifts smoother, blinkers are also at a normal pace now! I can't thank you enough for the recommendations! I've learned a big lesson here! Thanks so much! I need to post a new ad for struts, please help if you can! Thanks again! Rob

"I love it when a plan comes together"
:iceslolan

Rob, thanks for the feedback!

I just put that pic on here to show what a 1992 PA Ultra with 175K should look like. The car has never been to a dealer (rip off joint) for any repairs or trouble shooting. It has been meticulously maintained by me.

Happy to here your car is doing better. Did you put the 140 amp alternator in? I forgot to mention that if the car is driven only on short trips, the battery rating is even more important and so is as a good working alt. Think of it this way, you get in the car and the car may have been sitting for several days, (some battery drain), you start the car with the air on and possibly the lights (if you have daytime running lights), the alternator has to struggle to keep up with the current demand, let alone bring the battery back to a full charge. You stop at the market, (5- min drive) and come back out and repeat the process. Over a period of months, a regular battery will begin to deteriorate due to the lack of a full charge. It is then, that the alternator is put in the position of full charge every time you drive, therefore it will shorten its life. A larger battery with extended drain time will not discharge as much under similar circumstances, and you will have less strain on the alternator to bring it back to a full charge.

I am not surprised that your car runs better after your upgrades, since the computer controlled cars are very sensitive to voltage drops. A small battery with the air on, other accessories on, a low amp alternator, and driven at a low RPM, can drop voltage to the level that the sensors, PCM and ignition related components begin to act up. Everything is designed for a full 12 V + to operate normally.

I don't think you will have any more problems!
:shakehead

Me too! I did fill the battery tray up with a 930 ca batt., with 115 reserve, and upgraded the atl. to acdelco 140 amp., not one problem yet! Everything in the car runs better, the coolant gauge does not read above 200 anymore, idle is smooth! All the lights are brighter even with the engine off! I've been baptized by acdelco! I can't thank you enough!

Your car is just flawless! You for sure have a hand in talent! I've already copied it to my desktop! :evillol: I will keep in touch, thanks again, Rob