Update

Whining Noise - YouTube

This is the noise I was experiencing above. My symptoms otherwise were

- Difficultly to start when cold
- Whining noise directly related to RPM, not speed or gear

The symptoms I was NOT having were

- Dead battery
- Dimming headlights/interior lights
- Low alternator output (always 14+ volts)
- Any other typical alternator problems

After taking off the belt I figured it must be the alternator because the sound disappeared with the belt off, and the alternator pulley was rough and noisy.

I updated this for anybody else who might be experiencing this, also questions/problems below.

tl;dr buy OEM








Hello,

I have an 09 Cobalt SS T/C with 85k miles.

For a little while now (almost two months probably, but much worse recently) I hear a supercharger-like whine that is directly related in pitch to the rpm's rising and falling. Being in gear or being at any speed seems to have no effect.

Are there any common Cobalt issues that make this noise? My first guesses are perhaps alternator, water pump, and idle tensioner but seeing as it's sort of a pain to get to that stuff I'd like to see if I could diagnose it.

No dead batteries or leaking coolant, yet. Or any trouble of any kind so far.

Can't get a good recording of it on my phone as the engine noise totally overrides the microphone, however it is getting really loud. Sounds like a dying cat.

If anybody knows what an older grand prix gt sounds like, it makes a very similar noise to what almost all those cars make for some reason.

 

Mods on car? Only during boost?

 

The way you describe it, it almost sounds like power steering, but yeah...maybe the alternator as you mentioned? I've heard those whine before as well. If it varies only with RPM and not gear / road speed it sounds like it could be something belt-driven. That pretty much limits you to a/c, tensioner, alternator, or something internal. Good luck.

 

Boost leak possibly. Had the same thing when I had one

 

Hum I would have never guessed boost leak. I have a boost leak at my IC coupling hot side. I had to order a 2.5 to 2 3/8 silicone coupler because the 2.5 to 2.5 was just too loose. Its an mPX intercooler.

Would be amazingly sweet if that fixed it. It seriously doesn't sound like it is but I hope.

Trifecta tune @ 23 psi, mpx turbo back exhaust no cat, mpx intercooler, hahn CAI are the power mods. It does not seem to relate to boost at all though.

 

I don't think it's a boost leak. Tomtwtwtw is on a good path. I know the sound you're talking about just from the grand prix comment. Sub'd for when you find out the cause.

 

It does sound like a power steering pump, but since it's electric steering I didn't even include it. Does they still make noises like this?

I made a quick video here at work. Please note that the noises are really distorted from the video on the phone. Like the radiator fan is much louder than is in person, etc. There is a cricket noise I thought was a normal sound too but perhaps its not (after a quick search).

 

Cricket noise is normal. If it's been gradually getting worse that is not good. Still on factory filled tranny fluid? Or recently changed?

 

she dont wine like my M62 lol

 

Bought it used 20k miles ago, can assume factory . Didn't think of that

Maybe worth noting I revved it to 2.5 k rpm max. Also while the noise is definitely related to the rpm, it's not 100% the same tone at all times. As in if I idle it can waver a bit even if idle is dead solid at 800 or whatever it is. Don't know if that rules out tranny noise or not.

 

What you're saying is making sense we might be way off and it not even be tranny. Hopefully it's not usually expensive when talking tranny problems.

But get your fluid check out and if needed changed you are due at your mileage. I'm part OCD with maint and do my tranny/coolant/spark plugs every 75000km, early but peace of mind.

 

Do you have a after market radio or amp? Have you thrown anything carelessly in your trunk?
Does it sound like it's coming from speakers or engine?

 

Definitely sounds like the engine. No aftermarket radio or amp. There has been stuff in my trunk however, a lot sometimes.

 

I had the same problem with my 10 ss it was the alternator bearings. I sat my car for the winter and thats what i heard in the spring. Dealer warrantied it for me

 

your electric power steering pump should not vary rpm.

 

What i did was disconnected my drive belt and it went away. Dont run it for long just enough to check

 

I forgot about this, I'll do it tonight. Thanks.

 

No prob hopefully this helped you out

 

Had to work on another car so I didn't have a chance to pull the belt, but here is a better video of the noise

Whining Noise - YouTube

 

I updated the OP after finding the problem. It was a little annoying because there were no other alternator symptoms, but glad it was simply that.

Now I have a whole other sort of issue. First of all, how the f**k is the alternator supposed to get in and out? Every direction is off by a 1/2 inch. Headlight removed, wiring moved out of the way, intake removed. Radiator hose did not help. I got it in after moving/bending all sorts of **** by a little bit and banged up the pulley and cover a bit. It seems like the only legit way is to remove the engine mount which is dumb.

I had to special order this from Autozone because they said it'd come the next day for free. It came the second day. Nobody else carried it. Autozone, O'Reilly, CarQuest, NAPA, Pep Boys. Dealers were closed, not that I'd pay that much. I'm planning on ordering from GMParts direct for a real deal since I hate reman alternators. But in the meantime it needs to be up and running so...

The second problem is that after I got it in I come across this:



I was ready to shot put that god damn thing into orbit. Sob story: I was moving the next day. So today my car is DIW at a house I no longer live at.

So after a hectic damn Sunday of moving and going to stores, I simply ordered this and hopefully I could make things work. The amperage seemed the be the same anyway.

NAPA AUTO PARTS

Let me know what you guys think.

BTW not a single store could figure out why my connector was different.

 

Mis-sort by manufacturer? Does the part# on the piece itself match the box? That is a weird one for sure...even for Autozone.

 

The part numbers matched, and the pictures of the part matched what I was sold (they were very detailed pictures and the plug was visible). So even I got another it would be the same situation.

I'm trying to figure out what that connector actually does and how am I supposed to know which way to wire it since the two wires are the same color.

 

NAPA AUTO PARTS

Here is a little tutorial for anyone who runs into the same problem I did. Order the part above.

Remove the wiring from the shroud, there will be a cut already there.



Strip the ends on the new pigtail.



Cut off the old connector (and strip the ends, not shown)



Since the wires are both the same colors on the connector I tested the alternators to see which wire should go where. Bad things might happen if this is wired backwards.

I'm testing each lead in the old alternator for resistance (ohms) to ground (the casing of the alternator is ground here with the black lead).



This shows a value of ~9. Now test the other side.



Open or infinite. I plugged in the new pigtail to the new alternator to test the leads.





There is a value (~11) for the left lead, and open for the right. I simply match the wires at this point.



Crimp with included butt splices



Stuff everything back into the shroud and tape it up. All done, worked fine. I just wish I knew why I couldn't get the correct alternator plug.

Check the voltage at your battery when you are done to make sure the alternator is running (when the car is on). It should read 13.5-14.5 volts