stylo_guy

Not necessarily, the timing chain tensioner being worn out/bad also causes the same timing chain rattle on cold starts

My 2007 with 2.2 had the timing chain rattle on cold starts only, I installed the "updated" version of the timing chain tensioner and now it starts nice and quiet every time

donbrew

There is no "updated" tensioner. It is the tensioner that was always used on VVT engines. GM just decided to deprecate the non-VVT part.
By changing it you are putting a band aid on the problem. the chain is still stretched the hydraulic tensioner just has a bit longer throw.

stylo_guy

Yes there is, the "old" version from the factory was a flat head that was supposedly low quality. The "new" improved one has a bump on it and is supposedly better somehow

https://www.chevyhhr.net/forums/how-...-rattle-46159/

GM Genuine 12608580 is the part # on Amazon, judging by the comments/reviews section on there this timing chain noise on startup is fairly common

Anyways, it worked for me. No more 1-2 second rattle on cold start. As for whether or not the chain stretched, who knows, mechanic said everything looked fine when he popped the cover to install it

donbrew

Superseded is not the same as upgraded.
Fine if your aim is to stop the symptom and ignore the cause. Obviously, it will "look" fine.
Did you look at the date of that cited thread? Read the red warning at the beginning and the entire thread, especially the last 3 posts?
There are a few different part numbers for the hydraulic tensioner but, it has always been used on the VVT versions of the Ecotec 2.2L and 2.4L.

Oldblue

And the 2.0 LNF !

PulpFriction

Plenty of stories of the newer design failing too.

At this point I would only consider GM, new design, new stock. It would take a good bit of experience combined with a bit of luck to justify just replacing the tensioner. I did it successfully in a 2008 2.2. Reckless cheap-out? You decide.

If the chain starts noisy but ALWAYS seems quiet once the oil pressure builds, it suggests the tensioner ratchet mechanism has failed. I think this is more likely in the old design.

Considering the cost of a catastrophic chain failure, the conservative move is to at least open it up and see what's going on.

Cue debate on whether the tensioner should be "pre-activated."

Oldblue

Yes the tensioner must be activated after you install it!
the flat head style tensioner was for the 2.2 non VVT Ecotec
the dome head tensioner is for the VVT engines as mentioned above.
if you have cold start rattling, remove the valve cover and inspect the front chain guide.
you decide, change timing chain and rest assured your engine will last longer or go cheap, install just the tensioner and lay awake all night wondering if tomorrow is the day the stretched timing chain takes out a valve or 2 for breakfast
To me it’s common sense. But I’ve changed about 130 timing chains in my time, people convinced it was only the tensioner, when it was the front guide!

RJ_RS_SS_350

Agree. The tensioner doesn't "wear out". The chain stretches to the point that the tensioner has no more travel, and then the piston falls out of the tensioner housing. It has been speculated that the VVT tensioner has slightly more travel.

Your mechanic would have no reason to have the timing cover off just to replace the tensioner. He would have the valve cover off, so that he could release the new tensioner after installation. This would give him a limited view of some of the timing components. After installation, he could look and say, "yep, it's tight now", but no way to tell how stretched the chain is, without removing it and comparing it to a new one.

unknwn

"...to tell how stretched the chain is, without removing it and comparing it to a new one..."
I don't know if the factory service manual provides the needed specs, but chain stretch of these mini-roller chains, -and- the multi-plate 'silent' style are determined by caliper measurements across a specific number of connecting pins when the chain is appropriately tensioned.
There is NO suitable determination possible via simple visual inspection -or- comparison to a new part without -difficult- measurement s as previously described.
There is so little projection movement to an installed hydraulic adjuster via the geometry involved, that wear paths across slider & adjuster shoes can equal 'outside of acceptable adjustment' with no warning -but- noise from the cam-drive chain assembly.