Hi everyone,

I recently replaced my alternator after my lights started flickering and eventually my car dieing. Afterwards it always made a high-pitched whine when driving that I assumed was the new alternator. (Aftermarket from autozone)
A few months later now and the sound is still there but now the voltage is fluctuating from 12.2-14.6 at idle when it should be around 14 constantly. I noticed it at a light when a kind of purr sound started, almost like a fluctuating idle but it's not the idle, the problem goes away when I'm driving at speed and seems to come and go as well.
When it happens the voltage drops near 12.6 which is worrying and the lights flickering( dome and headlights, not the dash) Also noticed the voltage drops when the AC is on at idle and returns to normal when off.
I'm thinking it's probably something simple like a loose belt I didn't tighten to spec, or could the aftermarket alternator cause this?
I'll be doing the timing and alt belt replacement soon + water pump so I'll be able to check any suggestions.
All help/suggestions are welcome, thank you!

Car is a 2005 Civic LX ~ 173K miles, on another note is there a longevity thread for the longest lasting 7th gens? Just curious

 

When was the last time you replaced the battery?

 

Replaced the battery with the alternator

 

Did you happen to check the status of your battery cables? Is there any damage or corrosion to the cabling leading to/from the battery and chassis?

 

autozone alternators are garbage, take it back and get a name brand one

 

The cause is probably the alternator.

 

Thanks for the replies everyone, I decided to check it out today and noticed while removing the alternator that the tensioning wingnut was completely missing. Either I forgot or didn't tighten it enough originally.. I was working with my dad and probably rushed..

Heading to a salvage yard tomorrow to look for a replacement and will look for an original alternator as well.

On another note my positive battery terminal is corroded pretty badly, I'll need to replace it too

This is the piece missing: The wingnut is missing

 

Update:
found a stock alternator but I don't know the milage on the car it came from so it's a bit of a gamble. I noticed the old alt is kind of greasy, and my ps pump has some grease as well. Could the ps or something else be leaking onto it?
Greasy ps pump, normal?
Old on the right, junkyard one on the left

 

Final update:
installed the junkyard alt and new ps and alt belt, went for a test drive and turned on every accessory, no belt squeal and everything sounds good, voltage drops to 12 though with AC and fan on max though.. but returns to 14 when off . Any ideas or is that normal? If everything runs fine I guess I'll consider it normal but if it acts up again I'll make another post. Thanks everyone

 

it should stay around 14 volts no matter what you put on, you can just replace the brushes and you should be good