UPDATE: Video of actual noise on my car posted. Thanks!


Cobalt SS/SC rattle noise.... - YouTube



Idler pulley assembly on order....we will see?


I have replaced the following with new OEM parts.

1. LNF Timing Chain Tensioner
2. New S/C coupler with fluid
3. New Serpentine belt tensioner
4. Replaced belt tensioner pulley (didnt fix...put old one back on)
5. Replaced idler pulley assembly

I have done all of this......inspected for exhaust leaks (non found), and tightened all bolts on mounts and pulleys.....blah blah....

The noise GOT worse after the tensioner was replaced....but settled back down and has not gotten as loud as it was once the tensioner was installed.

I had it scoped and its coming from the tensioner area.....so ordered one up!

Edit: Didnt fix....

Again to be specific the noise does not occur with the belt off of the vehicle! PLEASE HELP!

Double edit: PLEASE HELP!


I was told my crank pulley could be noisey. I found a similar noise on another car on the tube......sound like it?

Sounds like this?

 

Does that M90 have a bypass valve?

The easy way to figure this out is to take a really long screw driver and put the plastic handle to your ear and start probing **** with the tip of it. Whatever is making that noise will be pretty loud in your ear.

How were the bearings in the snout of the blower when you did the coupler?

 

alternator or idler pully

 

dunno. not mine. but as you know the m62 the ss/sc has, has one. i tried the whole stethoscope and its not real helpful. The coupler was fine....bearings seemed okay? This sounds like the bearings in the back of the s/c? I mean that vid sounds REAL similar.

 

Yeah, that is certainly the sound of a bearing that is in the process of failing, or at list in that vid maybe a closed/non-existent bypass valve sound. Try the stethoscope again. If that doesnt work make one from rubber tubing and foam cups.

 

idler pulley? i thought that too. I cant find anyone who has had a similar noise though. All they complain about is squealing and such....no rattling.

Im going to take off the belt again tonight and make sure its still absent with the belt off. I would hate to work on an old assumption.....ugh. Thanks!

 

Wait I just remembered when I had this noise. The bolts on my pulley hub had backed out and one of the bolts on the tensioner were loose.

 

i checked my bbpv and the lines are right as they have been since before the noise. I checked it and it is actuating correctly. Thanks!

Im gonna check the idler pulley tonight and see whats what.

 

the hub is pressed in. my bolts on the actual pulley are tight. i checked last night when i installed the tensioner and the 13mm bottom bolt is tight and the top allen head bolt is tight as well. my old tensioner had some side to side play when tightened all the way and this one has VERY little. From what I have heard some play is normal.

off topic, but any pics of your car? i used to have a 03 base model cav with all the bolt ons, lzm stage 2 cams, all that. miss that car....was pretty quick imo.

 

had the sm and a tech look at it today.......

confirmed the noise is not present when the belt is off.

the noise sounds loudest from the oversized tensioner pulley. and not as loud but present on the idler. figure i may replace both. anyone have a part number for the gates oversized pulley? if i can get one local then i would love to do that instead of waiting a week. please? our dealer is in network with a gm place so i can get the idler next day if need be.....

thanks and please if you have the part number and have it pm me or post here. i prefer pm because as another op said I dont wanna hurt zzp or ottp sales....they have some top notch stuff.....but i dont wanna break down because my pulley seized!

thanks!

 

when the needle bearings in my tvs went bad, it sounded a lot like that...

 

This is the noise.....my car....read description of vid for update.

 

Bump. I updated the post with more information.

 

any update? i have a similar sound and thinking it might be supercharger bearings

 

Yes it was fixed. Thought I updated this, check the video description.

Take the belt off your car, reach down and spin the alt. it should turn both ways.......mine was one way and the pulley would slip the other.

Lemme know if you need help! PM me.

DONT BUY A WHOLE ALT if it does. You can either buy a replacement decoupler pulley for like 100.00 or a lightweight pulley for like 60.00