I searched the forum and another cobalt forum and came up with nothing on this topic. My 2009 cobalt ls 2.2 LAP has been having a cold start knock on startup. It has been happening every day. The temperatures have been around the 30s-40s. If anyone has had a 99-02 silverado/suburban with the vortec motor, it sounds exactly like that cold start knock. I thought this issues would have been fixed. It seems like everyone on here has no cold start issues. Im having a cold start knock that is a middle to loud volume knock. The oil level is at full on dipstick. Car has 8600 miles on it. I changed oil at 8500 to synthetic because i have been having this issue since 8000 miles on cold start up. Issue is still there. I searched google as well and had no assistance to this issue. I dont want to take it to the dealer yet and get the its normal for the car speech if it really isnt. Is this a new VVT design issue or is it perfectly normal with the short skirt pistons still? Any insight to this issue would be appreciated. Thanks.

 

mine always has a rattle/tick/knock... change your oil back to the dealer oil or they will void your warranty if they find something wrong with the motor

 

I personally know the service manager and they know we do the oil changes and I keep records. I just think having a cold start knock is crazy on a brand new car with this low of miles.

 

Is it piston slap by chance?

 

thats what mine sounds like... is piston slap or a vaccum leak but i cant find one

 

yeah sounds like piston slap...is it still "normal" even on 09s?

 

i sure hope so... my b2b warranty is out already and almost halfway through my powertrain...

 

Injectors ticking?.. My L61 does. It's common.

 

cold starts can sound like diesels when its really cold...it all depends on the temp...warmer making it quieter and colder making it louder

just never beat on your car when its cold

i like mine to get at least 80-100* before i start driving