Hi, I have an 03 Monte LS and the noise started yesterday, only lasts for a minute or so, until the car warms up then I dont hear it again until the next day when the car has been sitting for 8+ hours. It doesnt happen right away, the car will be idling for a few minutes before the noise starts up, then about a minute later it stops.

Started happening yesterday. Never heard it make this sound before in the 7 years I have owned it, I had a bunch of work done on it last monday including an engine tune up and new intake manifold gaskets and It never made this sound before then so maybe they messed something up? I plan on taking it back to them so they can fix it. But that wont be until monday.

The serpentine belt is new, just had it replaced in october, water pump is new, not sure what else could cause the noise, it had to have been something they did when fixing it last monday.

What do you think the sound is? Serpentine belt? Alternator? Belt tensioner? Hopefully nothing expensive.

as soon as it started happening I pulled out my phone and started recording so luckily I got it on video so you can hear what it sounds like.

 

It sounds like maybe something is rubbing against the belt. Maybe it's routed wrong?

Hard noise to ignore

 

That's possible. Tonight I let it idle and it didnt make that sound at all, very strange. I took it up to bell tire this morning and they couldn't get the sound to replicate and didnt know what could be wrong. I got the tune up on monday, two days went by with no issues, then it started making that noise thursday and friday night, and tonight nothing.

The only thing I can think of is toat maybe they tightened the belt too tight and driving loosened it a bit but that's a shot in the dark guess.

 

Almost sounds like something fell into the Alternator? how is the power steering pump? When it happens again tap stuff with a screwdriver handle. and see what happens to the sound.

 

Its possible that when they were working on tuning up my engine something fell into it, but idk. It started 2 days after the tune up, then made the noise once for two days in a row, then the last two days i've heard nothing when i try to replicate the sound. I dont have any issues steering or hear any PS pump noises. Car seems fine now, absolutely no idea what that was all about.

This is a separate issue, sorry for going off course from the above problem, but I do notice my rpms kinda dance around a bit sometimes, I think the IAC valve, or MAF might need cleaning, maybe the throttle plat too but i noticed today that the RPMs sometimes will stay at 1100 when my foot is off the gas, but will adjust when i brake, not sure if its related, its been happening for a month or two now. When i'm idling/stopped sometimes the car will rev up two or three hundred RPM's and do that in quick succession with maybe a second inbetween each rev, it'll do that maybe 4 times. Seems to have trouble finding an RPM sometimes. It usually idles at about 600 rpm, not sure if thats good or not. but I notice sometimes, not often it'll just all the sudden rev up to 900 rpms when idle even when its hot and been driving for an hour, really weird. I dont hear any noises, no clunking or knocking, it just revs up sometimes. Nothing crazy though, like it's never gone past 1000 rpm. Having the Air on or off doesnt seem to affect it, it does it either way.

EDIT: Forgot to mention that the first time the car started making that weird sound, i smelled something burning, but no smell the second time, and it wasnt as loud as the first time it happened as it was in the video. So maybe something knocked loose or was stuck in there but got grinded down so much that it doesnt make a sound anymore.

 

Your alternator sounds like it is going out. Did that shop "swap" it out for a sale to another customer? It has happened to me!!

 

I certainly hope not, if i find that out they did they're gonna have a lawsuit so big i'll be able to buy myself 10 new cars. I've given them over $6K fixing that car up and they always seem to find something wrong almost every time I go in so idk. I havent heard that sound since. I'm taking my car to my dads friend tomorrow and he's going to put in a new idle air control valve and clean the throttle body and MAF sensor, not sure if i should buy an alternator or not and have him do that too...

 

I listened to your video again and again. To pinpoint it, you can buy a mechanics stethoscope. it has a long, hollow, steel tube to place against the engine parts in question. From what i have been hearing, it sounds like the belt tensioner pulley bearing. Take a 15 mm socket and ratchet and rotate the tensioner counter-clockwise to loosen the belt enough to slip it off the alternator pulley. Next, reverse the ratchet and turn the 15 mm bolt clockwise to remove the pulley. Its "lefty tightey, rightey loosie." Put the bolt through the new pulley and tighten it by turning it counter-clockwise(lefty tighty) then reinstall the belt.

 

Hi, thanks for the response. I would have to have someone look at it, I have a tendency to mess things up and something as important as my car, I just dont feel comfortable taking anything apart or messing with anything. I know someone who can look at it and replace stuff if needed. I just had him replace my idle air control valve and clean the throttle body and MAF sensor and he only charged me $40. However I do have a video i recorded of my belt tensioner, it's wobbling a little bit and I'm not sure if its normal.