Alternator troubles
Thread Starter
TECH Regular
Joined: May 2005
Posts: 470
Likes: 4
Alternator troubles So I recently replace my alternator due to excess voltage drop at low RPM.
Now it seems it's the other way around - at WOT when it gets to 5500 RPM the volts drop to just below 13, then goes back up to 14 when the RPM's fall below 5000.
This is a new, not remanufactured alternator from Remy (91411).
Any idea why? I can't believe I'm having all these issues with LT1 alternators...
Now it seems it's the other way around - at WOT when it gets to 5500 RPM the volts drop to just below 13, then goes back up to 14 when the RPM's fall below 5000.
This is a new, not remanufactured alternator from Remy (91411).
Any idea why? I can't believe I'm having all these issues with LT1 alternators...
Could possibly be belt slip but If it were my car I wouldn't worry about it. I couldn't even tell you what my voltage is at 5,500rpms is because I'm to busy driving lol. I've had many that always run 13.5 volts and never had an issue.
Have you tested the voltage from the charging wire with a volt meter? What alternator? So far I've been having good luck with an A/C Delco remanned from Mexico I picked up off Amazon.
Thread Starter
TECH Regular
Joined: May 2005
Posts: 470
Likes: 4
The alternator is a brand new Remy 91411 made in Mexico. I see that pretty much any alternator new or rebuilt is from Mexico so I feel like I am gambling with alternators and am losing.
I really don't know what to do. I might start looking for an original from a low mile wreck.
I really don't know what to do. I might start looking for an original from a low mile wreck.
Are you running an u/d pulley? Have you tested the voltage with a volt meter? At idle you should be seeing a steady 14.2 to 14.5 volts.
Last edited by SS RRR; Aug 1, 2017 at 10:00 AM.
Trending Topics
Thread Starter
TECH Regular
Joined: May 2005
Posts: 470
Likes: 4
No underdrive pulley. Volts are steady at idle just not when approaching red line. I know it's the alternator as this was not happening with the previous alternator. Trying to figure out where to purchase a reliable alternator from (already tried new Remy, new ACdelco (which was bad right out of the box)....both made in Mexico with obvious lack of quality control).
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo
Awesome K5 Blazer Restomod Comes With C7 Corvette Power
Verdad Gallardo
10 Camaros You Should Never Buy
10 LS Engine Myths That Refuse to Die
Verdad Gallardo
Thread Starter
TECH Regular
Joined: May 2005
Posts: 470
Likes: 4
Got a reman from classic industries. They use BBB as their supplier which includes a test sheet which reassured me the part was actually tested before it was placed in the box.
Just installed....and voila! This resolved my issue with the volt dropping at high rpm, the volt gauge stayed consistent all the way to the red line. Sent my "new" piece of junk back for a full refund.
I really hope this lasts...
Just installed....and voila! This resolved my issue with the volt dropping at high rpm, the volt gauge stayed consistent all the way to the red line. Sent my "new" piece of junk back for a full refund.
I really hope this lasts...
Thread Starter
TECH Regular
Joined: May 2005
Posts: 470
Likes: 4
If I knew I was gonna have all these issues I would've kept my old alternatorbinstead of sending it as a core.
my current alternator has 14.44 volts cold idle (2 alternators ago was 14.7). 13.97 hot idle no load, 13.7 hot with a.c. on and parking lights so I think I finally got a good one (the fan pulley doesn't have the best paint job but I'm just glad the alternator works).
my current alternator has 14.44 volts cold idle (2 alternators ago was 14.7). 13.97 hot idle no load, 13.7 hot with a.c. on and parking lights so I think I finally got a good one (the fan pulley doesn't have the best paint job but I'm just glad the alternator works).
While it looks like the alt was actually the culprit for you, its worth mentioning to always use a MM first.
The dash gauge can be quite a bit off - mine shows a full volt higher then actual. After swapping my Alt I panicked when my gauge showed over 15v at idle, but when I tested with a known quality DMM straight off the alt cable it was a much more reasonable 14.4v output. If anything it would be lower then that at the gauge due to voltage drop over the wiring, so I have nothing to worry about.
Kind of weird since I don't hear much about the voltage gauge being off, but when dealing with old electronics these things can happen.
The dash gauge can be quite a bit off - mine shows a full volt higher then actual. After swapping my Alt I panicked when my gauge showed over 15v at idle, but when I tested with a known quality DMM straight off the alt cable it was a much more reasonable 14.4v output. If anything it would be lower then that at the gauge due to voltage drop over the wiring, so I have nothing to worry about.
Kind of weird since I don't hear much about the voltage gauge being off, but when dealing with old electronics these things can happen.
Thread Starter
TECH Regular
Joined: May 2005
Posts: 470
Likes: 4
Indeed. I know the gauge is not as accurate as a volt meter but my gauge was dropping to 13 or less volts at 5500 rpm. After installing the latest reman alternator that stopped happening. Volts stayed between 13 and the next mark all the way to redline (around 14 volts).
