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My 07 Cobalt is about to hit the 100,000 mile mark on it's 2.2L motor. I've read a lot about the timing chain needing to be replaced about now. My question, can I change out the tennsioner and not change out the chain? Or is it best to go ahead and change both out with this many miles? I understand there is an updated tennsioner that should replace the existing one. Apologies if this has been asked already. I couldn't find anything to answer this question..
 

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I think I misread the question
Coby to change the tensioner you still have to pull of the valve cover to release the tensioner right?

Not sure if there were any tricks to get around that. I don't know of any.
 

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Yes, that is the safest way, eventhough some people have done it without it. The tensioner releases the minute the chain rattles around on the guide, but I don't think I would chance it on a 100K miles car. Removing and re-installing the valve cover is easy enough. That's the way I did mine, it took all of 20 minutes.
 

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I'm not getting any noise yet, so I'm hoping I can save this for some warmer weather... Just doing my homework before I get into it.
 

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This is just me, but if you're going through the work of changing timing chain tensioners, why not take time to also complete required maint. (chain/belt & water pump)? Maybe I'm drinking the koolaid, but 100K service in my mind is one of the important motor milestones and timing chain/belt failure is catastrophic results so I say peace of mind's worth a little extra time. Am I wrong...??
 

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You can change the tensioner in 30 mins, the t-chain/balance shaft chain /wp will take you 5+ hrs and cost a bit more..
Sometimes if it isn't broke I don't fix it
 

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Maybe I haven't talked to the right people, but I've never heard of a timing chain failing. Belts are another matter, but I've known people with GM vehicles with 200,000 to 500,000 miles who've never touched the chain and it's still working just fine when the vehicle goes to the junk yard.
 

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Timing chains won't break but they can stretch to the point where the tensionner can,T keep it tight and it will jump timing. Yes, some last a long time if you do regular oil changes and keep it topped up. But I read some horror stories on here. Just do a little search about timing chain and you will see quite a few. I've been on this forum for about 2½ years and at least a dozen have reported timing chain failures.
 

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Maybe I haven't talked to the right people, but I've never heard of a timing chain failing. Belts are another matter, but I've known people with GM vehicles with 200,000 to 500,000 miles who've never touched the chain and it's still working just fine when the vehicle goes to the junk yard.
My Dodge D50 timing chain jumped and the motor literally grenaded inside...sold it for scrap. Guess, in my case, it didn't snap/break, but jumping the teeth was probably as bad, or worse than belt snap.
 

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Yeah, and the Ecotec is an interference motor so you don't want timing to jump more than one tooth because at 2 it will self destruct. I think changing the tensionner is a good preventative maintenance especially if he still has the first design. Revised version on the right is a much better design.

 

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Oh my...when spring comes I think I'm going to get that new design tensioner. Stop that morning rattle
 

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If yours is rattling in the morning this is the cure. Mine hasn't made one little noise since. Remember the longer you wait the more you are beating the chain guides.
 

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True. I don't know maybe I'll do it sooner.
 

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i definitely have to do it, morning rattles bring chills down my spine
 

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My guides look like new but I'm still displeased with the noise
 

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Yeah, and the Ecotec is an interference motor so you don't want timing to jump more than one tooth because at 2 it will self destruct. I think changing the tensionner is a good preventative maintenance especially if he still has the first design. Revised version on the right is a much better design.

Any idea what year they redesigned it??
 

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The engine manufacturing plant kept installing the old design even after the revised version came out in 2008, so you may have a 2010 still with the old tensionner. To verify just check for a bump in the middle of the 32mm head bolt. If your head is perfectly flat like this one you have the first design and probably hear rattling upon first startup if it's been sitting for a while.

 

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Any idea what year they redesigned it??
I checked my 2010 Cobalt today, it has the original tensionner and is the revised version. My 2007 didn't have the new version so maybe we can narrow it down a bit. Easy to check, just feel for a bump in the middle of the 32mm head.
 
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