Im no expert, but it could be a sticking lifter. I would bet it would go away after a good drive.
Personally, I would make sure to run it every couple weeks.

 

I'm just curious where these "Lifters" are since it's a DOHC motor ?

Which both overhead cams open & shut the In. & Ex. valves.

 

In the DOHC engine there are "hydraulic cam followers". This is the same principle as a lifter, but usually in the form a a "cup" that sits on top/around the valve stem and below the cam lobe. Otherwise you would need some way to manually adjust the valve clearance. The shop manual shows this, but the photo resolution isn't clear enough to be worth posting here.

You will also note that there is no maintenance or valve adjusting specs for the engines as the "hydraulic lifter" requires no adjustment.

 

Ok, the hydraulic roller finger, ~aka~ hydraulic cam follower.. 10-4

Just not familiar with it being referred to as a 'lifter'. Thanks Gene..

 

If the noise is rhythmic, and is coming from directly under the valve cover, then a cam follower may be the most likely cause. I have not heard of this being very common at all in any of the Ecotec engines. If it persists, since they are up top and easy to get to, and assuming that you are no longer under warranty, I'd find the culprit and replace it.

My '99 Trans Am has one that comes up after I get it above idle. It however, has 150k miles on it.

 

Must be all that Dihydrogen Monoxide you put in the tank when you put it away for the winter. Should have tried Nitrogen instead.

 

No one ever told me that!!!

(Just kidding!!!!)

 

SSGuy, I can relate. I'm still struggling to translate 20+ years of German car experience into the world of GM. So I wouldn't try to "cash" all my terminology, but I can usually get the point across. I have the HHR manual and like most it's obtuse and almost wholly useless for an "outsider", but I can usually correct my vocabulary with it. :)

 

Gene-
I know you have a Very extensive background with German autos & etc..
I certainly can respect that..

My Biz is mostly Harley-Davidson builds & etc.
But for the last 11 years I've had my Chevy S-10 with a Vor-Tec, & now I'm on my 1st Eco-Tec...... So bear with me...LOL..
Billy

 

the ecotec has very loud injectors because they operate at over 50 psi, makes them a little noisy, also the motors will have loud valve chatter when the engine is started when its cold and the valve train is waiting for oil on the startup.