Is my alternator going bad or is it something else?
Well the alternator is checking out fine. So now on to the ground straps. Where all do I need to check. Back of the passenger head, driver side on the block under car. Anywhere else? Exciter wire what voltage do I need to be at? They basically said its good, but it could be going bad... That is how it tested lol. I drove it for about 30 minutes today around town and it never once did it again.
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From: Haslet, TX
OP.. I had mine tested at three local auto parts stores and it passed. It wasn't until I took it to the guy that built my powerglide that I learned the alternator was garbage. While testing it and putting the engine under a load the alternator would fail. Something about the ripple in it. Those little belt testers at the local parts stores can't always tell the true story of what's going on with the alternator.
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From: Bossier City, Louisiana
If you have a local rebuilder, take it to them for the alternator test. They will very briefly "full field" test the alternator to put it into max amperage production and do the "ripple" test. Ripple is a measure of how much alternating current is leaking past one or more of the diodes in the alt's bridge rectifier. This is typically a very tiny amount - fluctuating around 0.05 volts AC.
Rick
Rick
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All kinds of wierd **** happens with a failing alternator....and its not really a failing alternator, its the voltage regulator that starts acting up. Mine, just a month ago would stall the engine when I turned the headlights on.....FREEKY. My A/C also stopped working, meaning the compressor clutch disengaged because the voltage was going wacky. Lights would dim also. Power windows were going up and down very slowly even before the alternator showed any signs of failing. Then it stopped charging while 4 miles from home and I barely made it home on just battery power.
I first just changed the alternator and all was fixed...............but then it happened again, alternator died. Barely made it home again. I took the battery to get checked and it was bad.......swapped the alternator under warranty, possibly from driving home on battery power, who knows. I bought a new battery and a new alternator and its back to normal.
CHECK the battery before doing anything. You might need that also.
I first just changed the alternator and all was fixed...............but then it happened again, alternator died. Barely made it home again. I took the battery to get checked and it was bad.......swapped the alternator under warranty, possibly from driving home on battery power, who knows. I bought a new battery and a new alternator and its back to normal.
CHECK the battery before doing anything. You might need that also.
Last edited by BigBoyWS6; Aug 16, 2024 at 10:31 AM.
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From: Haslet, TX
All kinds of wierd **** happens with a failing alternator....and its not really a failing alternator, its the voltage regulator that starts acting up. Mine, just a month ago would stall the engine when I turned the headlights on.....FREEKY. My A/C also stopped working, meaning the compressor clutch disengaged because the voltage was going wacky. Lights would dim also. Power windows were going up and down very slowly even before the alternator showed any signs of failing. Then it stopped charging while 4 miles from home and I barely made it home on just battery power.
I first just changed the alternator and all was fixed...............but then it happened again, alternator died. Barely made it home again. I took the battery to get checked and it was bad.......swapped the alternator under warranty, possibly from driving home on battery power, who knows. I bought a new battery and a new alternator and its back to normal.
CHECK the battery before doing anything. You might need that also.
I first just changed the alternator and all was fixed...............but then it happened again, alternator died. Barely made it home again. I took the battery to get checked and it was bad.......swapped the alternator under warranty, possibly from driving home on battery power, who knows. I bought a new battery and a new alternator and its back to normal.
CHECK the battery before doing anything. You might need that also.
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From: Schiller Park, ILL Member: #317
This might be an important consideration: I don't use my '98 Z28 very often, maybe one or two weekends per month during the on-season, but the battery never dies just from sitting for a week or two. In fact, if I don't drive it after two weeks then I put my smart charger on it, just to freshen it up, but it's still got 12.3-12.4v at the battery even after this two week period of sitting prior to charging, and will fire up just fine if I use it at that point...and that's with a battery that is currently 9 years old (AC Delco, bought in spring of 2015). So if you have a battery that's only 6 months old and depleting enough for a no crank situation in just a week or two, then either the battery is faulty or there is an excessive drain somewhere.
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I do know its got a 6 month old Delco on it now. Doesn't mean its not bad. It has gone down on me once. I keep my trickle charger on it when I know I am not moving it for a week or so. So far it hasn't done it again this week. I have driven it all but two days this week. Just around town, but its done nothing. I was hoping to take it to a car show this weekend which would mean putting it on the freeway. We are doing my wife's birthday dinner tomorrow afternoon with family and Sunday it is just entirely too hot to do a show. I will have to wait until next week to see what it does.
Replace that exciter wire with a beefier one. Check/clean all factory grounds. Do the Big 3. Only use Delco OEM (not remain), Powermaster, or a quality local rebuild. Replace the battery every 3 years unless you go Die Hard Platinum or Odyssey (or similar). Optimas aren't what they used to be. Delco AGM is good too, I do the Everstart Maxx and replace every 3 years. This TX heat kills batteries.
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Replace that exciter wire with a beefier one. Check/clean all factory grounds. Do the Big 3. Only use Delco OEM (not remain), Powermaster, or a quality local rebuild. Replace the battery every 3 years unless you go Die Hard Platinum or Odyssey (or similar). Optimas aren't what they used to be. Delco AGM is good too, I do the Everstart Maxx and replace every 3 years. This TX heat kills batteries.
I only have a 1,000 watt amp and one 12” woofer with Matt’s speakers in the back seat and doors with tweeters.
Is it hard to install the Big 3 kit? I’m sure there’s YouTube vids of the install, haven’t looked yet.
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From: Haslet, TX
This might be an important consideration: I don't use my '98 Z28 very often, maybe one or two weekends per month during the on-season, but the battery never dies just from sitting for a week or two. In fact, if I don't drive it after two weeks then I put my smart charger on it, just to freshen it up, but it's still got 12.3-12.4v at the battery even after this two week period of sitting prior to charging, and will fire up just fine if I use it at that point...and that's with a battery that is currently 9 years old (AC Delco, bought in spring of 2015). So if you have a battery that's only 6 months old and depleting enough for a no crank situation in just a week or two, then either the battery is faulty or there is an excessive drain somewhere.
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For the Trans Am people……about 2 years ago one of my headlight motors was causing my battery to die in a few days. Made no noise but I guess the motor or whatever it was electronically inside the motor was staying energized. I’m assuming once the headlight was operated either up or down and reached it’s “stops” that supposed to make the motor stop running, was staying energized.
I found out by pot luck. Right before I was going to have someone start trying to track down what component was the cause, I decided to replace both headlight motors with brand new motors with the metal gears that I installed into each new motor.
Bam……no more battery drain.
I found out by pot luck. Right before I was going to have someone start trying to track down what component was the cause, I decided to replace both headlight motors with brand new motors with the metal gears that I installed into each new motor.
Bam……no more battery drain.
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From: Haslet, TX
So here is an update. I went to a show on Sunday roughly an hour drive. I had gotten in and checked all the grounds and found the ground on the head on the passenger side snug but not tight. I figured ok that was it. I drove it for a week with no issues. Got almost to the show and it started doing the dropping on the gauge thing again. Made it to the show. Left and made it half way home and it started doing it again except it was dropping almost to 0. I pulled off the freeway and it came right back up to 14. I ease back on the free way and make it another 5 miles and it does it again. This time I am stuck on the toll. I finally make it to my exit and it goes back up. Its fine after that. I had to stop at the store went inside for 10 minutes and came back out. It fired up fine. So there is an auto zone across the street that I decided to take it to and have them check it. They couldn't test the alternator due to the CCA being at zero... So I babied it home and put it on the trickle and hopefully after this rain ends today I can get the 1 year old delco to work again and they can test the alternator that they swear is good again.
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So here is an update. I went to a show on Sunday roughly an hour drive. I had gotten in and checked all the grounds and found the ground on the head on the passenger side snug but not tight. I figured ok that was it. I drove it for a week with no issues. Got almost to the show and it started doing the dropping on the gauge thing again. Made it to the show. Left and made it half way home and it started doing it again except it was dropping almost to 0. I pulled off the freeway and it came right back up to 14. I ease back on the free way and make it another 5 miles and it does it again. This time I am stuck on the toll. I finally make it to my exit and it goes back up. It’fine after that. I had to stop at the store went inside for 10 minutes and came back out. It fired up fine. So there is an auto zone across the street that I decided to take it to and have them check it. They couldn't test the alternator due to the CCA being at zero... So I babied it home and put it on the trickle and hopefully after this rain ends today I can get the 1 year old delco to work again and they can test the alternator that they swear is good again.
i think your voltage regulator inside the alternator is going bad. They can work fine, work poorly and sometimes totally quit. Them work fine again. Till it finally shuts the bed and now you’re stuck somewhere on battery power. And with good battery you’ll get 5-7 miles of driving. It happened to me twice a few months ago.
You’ll need a new alternator. And it’s quite possible, like what happened to my perfectly good battery, all the craziness with the alternator messed up my battery.
I swapped both and all is perfect again.
And…..I had some wierd **** going on with my headlights, door windows and wierd sounds like the open door chime going off with both doors closed.
Strange, really crazy things happen when the alternator is on its way out.
*****Disclaimer……..it could also be low brake fluid causing all your issues…….these cars are FREAKS…….lol
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From: Haslet, TX
Your exciter wire could be about to break and it’s causing the alternator to intermittently stop charging.
i think your voltage regulator inside the alternator is going bad. They can work fine, work poorly and sometimes totally quit. Them work fine again. Till it finally shuts the bed and now you’re stuck somewhere on battery power. And with good battery you’ll get 5-7 miles of driving. It happened to me twice a few months ago.
You’ll need a new alternator. And it’s quite possible, like what happened to my perfectly good battery, all the craziness with the alternator messed up my battery.
I swapped both and all is perfect again.
And…..I had some wierd **** going on with my headlights, door windows and wierd sounds like the open door chime going off with both doors closed.
Strange, really crazy things happen when the alternator is on its way out.
*****Disclaimer……..it could also be low brake fluid causing all your issues…….these cars are FREAKS…….lol
i think your voltage regulator inside the alternator is going bad. They can work fine, work poorly and sometimes totally quit. Them work fine again. Till it finally shuts the bed and now you’re stuck somewhere on battery power. And with good battery you’ll get 5-7 miles of driving. It happened to me twice a few months ago.
You’ll need a new alternator. And it’s quite possible, like what happened to my perfectly good battery, all the craziness with the alternator messed up my battery.
I swapped both and all is perfect again.
And…..I had some wierd **** going on with my headlights, door windows and wierd sounds like the open door chime going off with both doors closed.
Strange, really crazy things happen when the alternator is on its way out.
*****Disclaimer……..it could also be low brake fluid causing all your issues…….these cars are FREAKS…….lol
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But my failing alternator seemed to kill it.
Last edited by BigBoyWS6; Sep 9, 2024 at 12:43 PM.
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From: Haslet, TX
Well the battery had a bad cell. So I had to replace that yesterday. I am going to have the alternator tested probably Monday. We are headed to Mecum this morning. The battery paper work was the only thing the previous owner didn't give me so the 14 month old delco got replaced for now with a Napa.
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Update: The Delco tested bad again. CCA is dead. So I decided to start there. Replaced it with a Napa for now and drove it over 100 miles yesterday. It did not act up one time. This is puzzling and I am not convinced its still not the alternator. I am going to take it on about a 50 more mile trip this morning to take me son to the doctor and see what it does.
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Update: The Delco tested bad again. CCA is dead. So I decided to start there. Replaced it with a Napa for now and drove it over 100 miles yesterday. It did not act up one time. This is puzzling and I am not convinced its still not the alternator. I am going to take it on about a 50 more mile trip this morning to take me son to the doctor and see what it does.
The NAPA battery that (did not act up one time) that you repalced that bad battery with is giving you no problems..........
All seems fixed......NO...?
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From: Haslet, TX
So both checked out fine the first time the gauge dropped. Both the alternator and battery. Then it was the second time when it really acted up the CCA showed 0 and nothing could be further tested. I then went straight home and put my trickle on it for 4 days and then went to have the alternator retested. Same thing CCA was zero and so we assume it had a bad cell acting up in it. It had in the past randomly went dead from sitting for 3 weeks, but I never thought anything of it. It didn't do anymore. I started with the battery because obviously zero CCA I needed one and I have put close to 200 miles on it and alternator has not acted up one time. I even ran the a/c to see if that would make it act up and nothing. So for now it's working. I need to go have the alternator checked now that it has a good battery on it. I will do that tomorrow.
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So both checked out fine the first time the gauge dropped. Both the alternator and battery. Then it was the second time when it really acted up the CCA showed 0 and nothing could be further tested. I then went straight home and put my trickle on it for 4 days and then went to have the alternator retested. Same thing CCA was zero and so we assume it had a bad cell acting up in it. It had in the past randomly went dead from sitting for 3 weeks, but I never thought anything of it. It didn't do anymore. I started with the battery because obviously zero CCA I needed one and I have put close to 200 miles on it and alternator has not acted up one time. I even ran the a/c to see if that would make it act up and nothing. So for now it's working. I need to go have the alternator checked now that it has a good battery on it. I will do that tomorrow.
The alternator is failing. Those damn things play tricks on us and make us chase our tails.