Blaze9

Hey,

So yeah, title basically. It just started happening today after some driving going 70-80mph for about an hour and half or so. The noise is noticeable at low RPMs, and the pitch seems to get louder/higher as you go higher in RPM and then it gets quiet/you can't hear the pitch anymore at around 3k RPM. I thought it was the fans, but I opened up the bay today and the fans were not spinning but the noise was still occurring, and that's when I got an estimated location (left side engine bay). Anyone know what it might be? It's a 2012 FWD w/ 95k miles.

Thanks!

2snail

could be the alternator. I just posted in another thread, had the exact symptoms on both my cars TLSHAWD and V6TSX and i had to replace the alternator on both. I think for mine, it was the batteries going out causing strain on the alternator. Might wanna check your battery. Also if you do replace your alternator make sure you go with the denso one which is what OEM is I believe.

I put a duralast one from autozone which crapped out a year later. Ended up putting a denso on in to fix that issue.

best of luck

Blaze9

Yeah I ordered the Denso one. Battery is fine, not a problem at all. I replaced it w/ an optima yellowtop and it's been going strong ever since. Just checked voltage w/ an OBDII reader and it was 13.2ish w/ the car on and 12.9ish w/ the car off.

Ninjamotion

You sure 13.2 with the car on? No other loads? Should read 14.1-14.2. Alternator for sure if 13.2!

jefflikesbagels

I had the same exact whine a few months ago, it was the alternator. If you want to be 100% certain, take a really long flat head screwdriver, stick the screwdriver side against the body of the alternator, then stick your ear to the handle side. If you hear the same whine sound but amplified, it's definitely the alternator.

Unfortunately you'll have to remove the left radiator cooling fan as well as the auto tensioner to get the alternator out. The center bolt on the tensioner pulley is actually a hex key head (IIRC it's 6mm), so I used a 6mm hex bit socket to get that out. Not much room down there for my fat hands. If you feel like doing some preventative maintenance you can replace the auto tensioner and the serpentine belt with new ones at the same time.

Blaze9

Yeah I got to it yesterday evening. Did Alternator, spark plugs, and the belt. Forgot all about the tensioner though, drats. I hope it doesn't need to be replaced soon!

The problem (noise and error lights) went away. I'm quite surprised that a stock alternator went out so quickly! I replaced with a stock one as well, hopefully it's not a reoccurring issue every 4-5 years.