No problem man. Even though thus far you are not getting the answer to the issue we might be getting closer to the issue by eliminating possibilities.

So it's still much appreciated!

 

Ok...the dealer changed their minds again...they listened to the noise again this morning (it being about 30F this morning so it made that nasty grinding sound again for them) After listening to it again they decided to go ahead with replacing the cam phaser. The are ordering the parts so hopefully I will have it back early next week! I will keep you guys posted and also try to get the bulletin info for you all as well. Hopefully this will solve all our problems. If this works take this thread to your local dealer and shove it up their you know what!

Dealers hate CobaltSS.net!

John

 

My car did this occasionally last year but only when it was below 0 celsius. I've been ignoring the oil life monitor and changing my oil old school style at 5000 "kms" or 3000 miles so oil deterioration is not the issue. If gettingausrnamesucks says that it will not harm the car then that's the end of the story for me. It is well below 32f right now and my car has not made the noise yet. If it gets really bad then I'm almost certain that 0w-50 will eliminate it.

 

Yes I agree that the type of oil that you use effects this in colder weather because when i was using 10W-40 and as soon as I switch to 5W-30 the sound was minimized but not eliminated. I think the damage has already been done by the thicker oil but we will see once I get the car back next week.

 

UPDATE: Got the car back and yesterday and started it this morning. It was about 20 degrees f outside. It didn't make a noise! Not a single grind or RPM drop. I'm happy.

I will try to get the bulletin for you guys tomorrow. Got to stop by the dealer again anyway to get a O2 sensor replaced. It threw a CEL as soon as I pulled out of the dealer lol. Guess they broke it putting it back in or something...

John

 

I haven't noticed any noises yet but I'm usually too cold to pay attention. I have noticed I do get really rough idling and the vacuum/boost gauge bounces on a cold start which should indicate a sticking valve. This is it's second winter but only experience a mild winter in Texas not looking forward to PA winter.

 

I've lived with my LNF for two years now, both years experiencing four season weather for ~62,000mi now. Temperatures ranging from 17F to 110F. Cold start sounds are definitely very different from your more temperate days.

I've never strayed from the 5W-30 recommendation, used Mobil1 and then switched to synthetic Pennzoil, based off of good results from oil analysis. The cam phaser reply sounds like an awesome explanation. I wish I could add something about the cam phasers topic, but just the word "phasers" sometimes baffles me and just makes me think of Star Trek. :-P

I watched your video to listen to the sound, and based on past experience with my engine over the last 62K, I hear the same noise below ~38F, although my rpm drop isn't AS dramatic. It does drop though, slightly. This may be a result of your usage of the 10W, but it's good to hear you've since then addressed this.
As a side note, on the warmer startups, you might notice the absence of what sounds like the AIR injection pump (sounds like a little turbine, and it usually kicks in on colder days at start up AND idling at operating temperature).

Hope this helps. :-)

 

Any new info on this issue? I have it and it is driving me crazy. The dealer changed the cam phasers and it did not fix the problem. They are telling me it is normal now. No way is this normal. Any info is appreciated.

 

If there is any info, it wouldn't be new because this was like almost 2 years ago...

 

My theory is that basically the noise is vapor lock like the old school mechanical pumps. Ours being due to the more volatile winter blended gas. (since it seems to only occur during the months that they sell winter blended gas) Also, unlike the old school pumps, we have an electric in the tank to send pressure and prime them basically.... so they snap out of it in a second.
The noise?..... probably the regulator having a hissy fit due to the fluctuation. When I get my car back together with dual interceptors I may try to see if this is true (by watching the fuel rail pressure)

That's my theory.

 

Does it on mine when 32*f outside or colder. Always has, im not worried about it

 

same here but my car is fucked anyways lol

 

Well unfortunately mine is still doing making the noise. It only happens on cold starts and its starting to get warmer out so at least I wont have to worry bout it till next winter! grr I know it is going to drive me nuts again come winter but at least I don't have to worry about it at the moment! Bigger problems like getting my car tuned for my BOV boy do these cars not like VTA BOVs