What brand and weight oil are you using ?
Have you changed brand or weight recently ?

 

The shop changed the oil when they did the timing chain. They said they used 5w30, what brand im unsure of.

 

I thought the new tensioners didnt have to be deployed ?

 

That's ... interesting. Would like to know the source of that tidbit. I don't think it's correct, but I've heard that, too.

GM says it must be activated. So do Cloyes and Melling.

Was yours installed without activation? If so, that would explain your experience. Likely the rattle upon cold start was due to a loose chain, due to an unactivated tensioner. But it would nevertheless pump up with oil and the rattle would cease. IDK how long it takes a pumped up tensioner to bleed down, but if it takes a while that would explain why you didn't hear the rattle when it was recently driven.

Now, there's a belief out there that chain slap will eventually activate an unactivated tensioner. In my opinion, it's surely true. Even if so, I would call it risky at best. I have never seen it recommended in writing.

To compensate for wear, an activated tensioner operates with a ratchet mechanism that advances incrementally.. That means the chain can't always be completely snug. That would explain sometimes hearing a slight start up rattle that eventually disappeyes as the tensioner increments to the next step. That has been my experience. I think.

The plot thickens. Melling made a video recommendind activating the tensioner before installation. That's a whole different discussion.

 

Easy to check: take the valve cover off and look at the chain; any slack between the sprockets is bad.

 

Very true Don. Just a little harder to do on the SS. Gotta be careful with a couple of those vent hoses/connectors. They can be a pain to disconnect.

 

For future readers here’s the process of activating or engaging the timing chain tensioner. All Ecotec engines require this step

Page 12 instruction #7

https://www.ddmworks.com/assets/imag...uild%20Kit.pdf