Anyone here ever hear knocking coming from the back of there Cobalt ss/sc. I hear it sometimes even when the car has just been parked and the engine is shut off. It sounds like someone is knocking on the side of the car?? Very strange.

 

yeah my car does this too. mine sounds like its coming from the muffler area. weird.

 

yeah it just happened to me about an hour ago while i was messing with my radio stations. it has happened plenty of times before that although i have no clue what it is... first time freaked me out cause it was at night.

 

HAHAHA yeah the first time it did it to me was at night too out in the country....freaked me out!

 

I get that too. It knocks 2 to 3 times and it's gone until I shut the car off and wait over night and start it back up in the morning. What the hell is that? I thought it was only my car. I think GM included a ghost in our cars for no extra cost.

 

mine clicks whenever i shut it off, get out, lock it, and got inside... im thinking it is just the engine and supercharger cooling down...

 

It's not clicking. It's knocking as if someone outside came up to my car and started knocking on my car. It comes from the right rear of the car on mine.

 

its probably one of two things....

If it is a pingy sound it could be the exhaust cooling down. The other option is the trunk latch checking itself.

 

I don't think it's either one. I can't imagine the trunk latch making this sound and the pingy sound isn't what it is.

 

dang i thoughtt his was going to be a knock knock joke. but anyways. mine does it to. mostly in drive threws

 

I'm telling you it's a GHOST. Don't belive me? Check this out http://www.princeton.edu/~ccaro/mist_or_ghost2.html

 

lol...thats good.

 

i get a for that link

 

You need quicktime I belive to view the file. It's pretty creepy if you ask me.

 

I prolly is a ghost, the Ghost of GM Employee Discount for everyone event pricing...

 

How about the gas in the gas tank moving around. My cavalier was really bad for this. Every time you were around 3/4 tank you would hear the gas move around?

Just another idea?

 

The best way I can describe it is to have someone knock on the right rear of your car lightly. It will sound almost exactly like that. I'm not worried about it I just want to know what the hell it is. I get it like once a week.

 

When you hear it try to keep a mental record of how much gas you have. If it is always somewhat around full area when it does it. Most likely it will be the gas moving.

 

Yeah I remember looking once and my gas was about 3/4 to full when it happened. I'll look at the guage next time. Idk it just freaks me out, especially if it's like 2 in the morning and it's really quiet out. (as you can see, i'm afraid of the dark lol)

 

I've posted about this," knock- knock- knock", noise before and was blown off! The EVAP system is testing itself! The noise is from a soloniod being energized by the PCM. EVAP system tests run under certain conditions. The tests will occur shortly after start up and just after shut down. The soloniod is activated to relieve vacuum in the fuel tank after it checked for leaks. (leave you fuel cap loose and see what happens).
But, I do like the ghost story.

 

Yes i think it is the gas moving, mine freaked me out the first time i heard it, but then i noticed it was the gas.

 

Ah yes the infamous Cobalt Ghost, I have yet to find out where it is coming from.... I will find it some day...

 

I was told the same thing by my service guy at the dealership. I've had that noise to so while I was at their shop putting a windshield in one of their SSR's, I happened to catch him and ask, he said it was the same thing.

 

Yes, I know nothing! j/k

 

I still think it was a ghost...