Replaced my alternator myself and it all seems to have went back together fairly well however I noticed two things. First off is a kind of "whistle" or "whine" that is more pronounced now than it was before. I thought it was a vacuum noise before but now that the belt could be too tight, it sounds like it is coming from the belt area.

The second thing I noticed is after the car has warmed up, the RPM is right on 650rpm. I'm not positive what it was before but I thought automatics were supposed to idle at 750rpm. It's worth mentioning that after my first spin around the block, I parked in my driveway and revved the engine but When the rpms came back down they dipped lower than 650 and the car rumbled a little before returning to normal idle.

Will loosening the tensioner a tiny bit be a good thing? I tried to get the tension as similar to the power steering belt but the power steering felt just a hair more loose. The belt I'm using has less than 20k miles on it and still in very good condition.

 

It is a 2003. Forgot this wasn't the 5th gen section. I read a thread from the 4th gen section and someone stated their FSM calls for .16 inches of deflection between the crank and the AC. I can get that amount of deflection with my fingers pushing on it. If its not the belt causing the RPM and noise anomalies could it be from having the battery unhooked for over a day and make the ECU "forget"?

 

you want the belt just tight enough not to squeal under load.. it certainly can't hurt to loosen it and see what happens.

Belts installed too tight can cause all kinds of problems- like destroying alternator and water pump bearings.

As for the idle, it's controlled by the ECU for the '03 models. if the belt is too tight, it could be having a hard time getting to the desired RPM, but it could be something else as well. the belt is an easy thing to adjust and see what happens.

 

I'm almost positive it is not the tension or the idler pulley. I have a video of the sound


I fear it is the NAPA alternator i put in there but it is charging fine so i don't know if I could use the warranty on it.

 

Since the sound seems to be in the vicinity of the alternator, you need to use a stethoscope (or equivalent) to isolate the sound. It could be a bad alternator bearing or it could be the belt tensioner pulley bearing or maybe the a/c compressor bearing. Since you didn't have the sound before you changed the alternator, it kinda points a finger at the alternator.

 

I did have the sound before but it wasn't as pronounced as it is now. Before, it only happened when it was cold. Maybe both alternators made the noise and only this one is worse, or maybe the AC pulley got worse when I relieved the belt tension . I'll have to find a stethoscope or someone with one to isolate the noise. The idler pulley and belt are practically new so I'm assuming a newer part wouldn't make that noise but I suppose weirder things have happened.

If it does turn out to be the alternator, I'm not sure what I'll do. The effort to change it outweighs the minor annoyance of the sound...until it fails.

 

if it's a reman parts store alternator, then it's very likely you got an alternator with bad/ noisy bearings. you can also ruin bearings or make them noisy with too much belt tension. that's why I mentioned the tension.. too much tension is WAY worse on the bearings and shafts than too little tension is. a loose belt is just noisy, but a tight belt will break stuff. keep that in mind.