I own a Cobalt SS/SC and it has about 12 000 km, I love this car but I am having a bit of an issue. I took my car into the dealership the other day because of some engine knocking. I broke the car in like it is supposed to and have changed the oil when needed so I don't see it being something that I have done wrong.
I took it in to the dealership and they are saying that they have no idea. They said they checked the lifters, injectors and that the noise is not coming from the bottom end, which is good to hear. I had to wait a few days because they needed an engineer from GM and apparently he has no idea.
So after all is said and done the only thing they can tell me is to take it home and wait until it gets worse.
Has anyone had any problem like this????

 

nope, keep us posted on what they say

 

By engine knocking do you mean the engines just sounds like its clicking when at idle?

Cause I have this too but mine is like brand new so I just thought it was normal

 

Can you go into a bit more detail about the knocking? What does it sound like? Where would you think it may be coming from specifically? Could it be the engine knock because of the octane you are using? Is it affecting performance? Could it be a rotating knock such as in the tranny or the like? Did GM pull any codes regarding knock retard?

Just asking to maybe get the juices flowing, (plus I want to know ) you might be able to give GM a head start by pointing them in the right direction!

Sean

 

Are you sure it isn't something bouncing around in your trunk?

 

Has it been an ongoing problem? It could be a bad tank of gas or it could be something more serious. You haven't put anything lower than 91 in it have you? I've noticed mine will run REALLY rough if it gets a tank/brand of gas that it does not like. Run it till it's almost empty, fill it up at a station you KNOW has good quality gas and see if it makes a difference.

If not, try taking it to another dealer and see if someone there can help you or like they said, see if it gets worse. Sometimes it has to get so bad before they're able to determine where the problem is and what exactly it might be. It may be right now that it's too minor to determine exactly what it is, it needs to get a little worse so they can pinpoint exactly what it is that's going on.

Keep us posted.

 

I was going to say that too, I heard a knocking yesterday and realized it was just my skates in the trunk!

 

a knock coming from the bottom end is usually a bad thing - aka engine aint far away from dying...

 

The Ecotec is a noisy engine period. Both my 2.2 and my 2.0 sound the same. Lots of clicking and other sounds. Even Car & Driver made a comment about the odd noises from new ecotecs.

Nothing to worry about, I have noises too. Runs great though!

 

The knocking noise is coming from the top front of the engine, near the supercharger. Before I took it in I thought that it might have been a sticky lifter. But they say that is not the case.
I don't think that it could be from the octane because I am using the highest octane that I can find, Which is 91.
From what I can tell it is not affecting the performance at all, if it is not noticeable. Also it is not showing any codes.

 

I forgot to mention that when I first picked this car up it did not sound like it does now. When I took it in I went with the mechanic and made him start it up and listen. He commented that it didn't sound good.

I am sure that its not coming from the trunk.

 

its probably just the bypass valve....is it constantly clicking or is it every once and a while? if its just clicking every once and a while then its ur bypass valve opening and closing....if its constant it could be anything...like the supercharger has a bolt stuck in it....lol which would really suck...but thats worst case senario....but anything else it could be is a bolt could be loose and rattleling....or maybe the pulley isn't on the supercarger right...

 

this may sound far fetched in your situation, but when the Mazda RX-7 first came out they had dealers replacing the motors left right and centre because no-one knew how to work on Rotary engines... not saying this is the case here at all but I've always been skeptical about how much dealers know about cars they are working on... sometimes a little shadetree mechanic expirence goes a long way in diagnosing a problem... all they do there is plug the car into a diagnostic machine, get a code and replace the part... no thinking involved. I'd get a different opinion from another dealer if they can't or won't fix the problem.

 

Actually to tell you the truth I think I hear a knocking sometimes that reminds me of the when I strut loose in my old VW, but I take it that its nothing that obvious. It happens while....? (idleing, driving, turning,accelerating) Give us more details man

 

If its a small knock or "ticking" it is actually the injectors. It's very common on cars with larger injectors. My engine makes this ticking noise even at idle and i picked it up with 300kms on it from the dealership...

The injectors are also at the front top of the motor. They are also the cheap plastic hi-impedence ones that have less bulk for insulation then the old fat lows did. It could be the dealer has never addressed the ticking injector issue so they don't even know what they are listening for.

 

I went and picked the car up today and had a long talk with the service guy. The dealership is saying that they can not do anything until they get an ok from GM. The dealership does not want to start ripping the engine apart until they have a better understanding of what is going on. So apparently some engineers at GM are going to research and see what they can come up with.

The "knocking" sound happens when idleing and then when you hit the accelerator the knocking speeds up with the reving of the engine.

So in the end I took the car home because they said it was ok to drive and that it wouldn't do any damage, but the engine sounds like crap.

 

Well...mine is an 06 with 2400 miles on it...and every night when i shut it off it clicks for a few minutes then dies down. The clinking ranges from quick tapping to not so quick tapping depending on how i drive it... Proabaly the bypass valve.

 

Actually i found out from a friend who is a GM Tech...that it is either Bypass Valve or Injectors. I dunno which because im not a Motorhead like that. I just like the looks, the speed. and the chicks i pick up in it.

 

Thats nothing to worry about, its just the exhaust cooling down. Just about every car does that, perfectly normal

 

Sounds like the timing chain tensioner to me, thats what mine was, and a few others have had the same thing:

"I went and picked the car up today and had a long talk with the service guy. The dealership is saying that they can not do anything until they get an ok from GM. The dealership does not want to start ripping the engine apart until they have a better understanding of what is going on. So apparently some engineers at GM are going to research and see what they can come up with.

The "knocking" sound happens when idleing and then when you hit the accelerator the knocking speeds up with the reving of the engine.

So in the end I took the car home because they said it was ok to drive and that it wouldn't do any damage, but the engine sounds like crap." i got so pissed about mine, the car was nearly new, they fixed it at my familys dealership, and it hasnt happened sense.... this was how mine sounded though, i thaught it was the charger at first, and then i was like no..... i put a screw driver up to the top of the cam cover, where the gears are, and sure enough, thats what it was, the chain was rubbing the inside of the case...... suggest that to the dealer man, and let me know how you make out

 

My exhaust ticks once it warms up, and for a bit once I shut down. I can do without it, but doesn't phase me.

 

thats the exhaust and muffler cooling down!

 

The dealership finally found the problem, and the problem is a valve clearance. The problem originated from the factory and over time and wear it has gotten worse. So what has to be done is a new head has to put in.
I have only owned this car for approx 3 months and it already has a problem like this. What is in store for the future????
I am being told that mine is the first to have this problem being fixed. But there are other cases. So if anything I hope this helps someone else with the same problem that I have.

 

That sucks man,I hope ya get back on the road ASAP. Bad Castings suck.

 

My engine is now making that noise too. It is the 2.4 so I know it isn't a supercharger noise.