Is my alternator giving out?

[Quest]

Alternator (rebuilt unit) typically costs around 150~250USD, with brand new Hitachi units as much as 350CAD here.

Is the whine coming from your stereo (speakers) or from underneath the hood?

 

[Quest]

Once again, no need to replace any parts yet...get proper diagnosis first (to better understand the situtation)

Q.

 

[ThirdeYe]

It's coming from under the hood. Stereo's crystal clear when off or paused or played a lot volume. I'm starting to think though, that it might just be the normal sound of the engine that i'm not used to (i've never had a Honda before this). I've been used to my old Nissan KA24DE which had a lot more torque and a deeper sound to it. I'm going to get a tire rotation/balancing today and check to see if it needs an alignment (it's kind of pulling to the right). I'll keep a lookout for a voltage reader and get that reading to you as soon as I can, also

Thanks for the help.

 

[ThirdeYe]

Update on the story, I had my uncle test it right after starting it cold and he said it read about 14V. I seem to have found out my problem though, just out of sheer boredom. While I was waiting for my mom to get out of the bank, I decided to wait in the car, and when I turned the car off after she got out and I had the stereo off, I heard a little "hum" come from the speakers, and as I turned the car off and the alternator stopped winding, it was right in pitch with the alternator. Sure enough, when I drove away again, I heard the sound of the whining/brushing actually coming through the front speakers, but they led me to believe it was coming from the engine because if you were sitting in the driver's seat, that's what you'd think it was, but I moved my head closer to the speaker in the door and found out that that seems to be where my noise is actually coming from! -doh- I've read that this could be due to poor grounding of the stereo, is this true?

 

[Quest]

ThirdeYe-

This was what I was trying to lead you to (remember the question: was it coming from underneath the hood ..."?)

Reason being as follows:

1. Japanese made alternators don't "whine" unless you are exerting excessive load to them (e.g. an extremely discharged battery that needs to be recharged, heavy stereo equipment, etc.) or a bad fan belt/serpentine belt.

2. given your initial description of loads of aftermarket subwoofer, amps, etc. I wouldn't be surprised if you get grounding issues (ground loop that comes in as a rpm-dependent variable pitch that sounds like "whining").

What you should consider doing now is to revise your amp/head amp/subwoofer unit's grounding and leave the alternator part alone (assuming that no alterations done to that part underneath the hood so far). Seek out poor groundings and deal with it from there.

14V after starting is good so no worries about replacing your alternator. Afterall: your issue isn't from faulty alternator to begin with.

Cheers,

Q.

 

[ThirdeYe]

The only alterations i've done under the hood are new spark plugs and some nice premium blue NGK OEM wires. I wasn't the one that did the grounding work with the stereo, i'm assuming it was the previous owner that sold it to me (he's the one that put the headunit and subs in). Thanks for all the help though, appreciate it. Kind of off-topic, but once in a while I start my car, when it's cold out and revs high, it usually sits at around 1900 rpms until it gets a bit warmer, unless I drive. Anyways, there's been a couple of times where I start it and it goes up to 1900 like usual, then it drops to 1500, then revs back up to 1900, then back down to 1500, rinse and repeat. Sounds like i'm revving the engine when i'm not actually touching the pedal. Any ideas on what this might be? Feel free to PM me so we don't take this thread in the wrong direction

 

[Quest]

Will PM you later.

Q.