After owning my 07 HHR 1LT 2.4L for a few months, I've noticed an irritating cold start noise. After the car sits all evening and overnight, the first cold start in the morning (still summer here, and car sits in the garage) makes a burbling noise for 1 or 2 seconds when started. After that it is fine all day long for startups, even after sitting for 8 hours at work. I run mobile 1 5w30 in it, oil level is correct, ony 2k miles on the oil so far. I've been reading about a cam phase change solenoid that could cause this from a TSB on the GMC Terrain and Chevy Equinox with the same motor. Anyone else have this problem? I have 34k miles on the car.

Also, this may just be the 2.4L motor, but when I wind it up, say above 3k RPM it really sounds like its being flogged and beat on. Don't know how to describe that, but just unrefined. My brother in laws 2.2L with 5spd sounds much smoother at high RPM. I run only Premium grade ethanol free fuel and usually shift at 2500RPM. But every once in a while, like merging onto the freeway uphill with the AC on and 4 people in the car you have to work the gas pedal a little more than usual.

 

Check yer anti-freeze (Dexcool) level when cold, under the cap & the reservioir tank..

IDK ? my '08 2.4 can wind to 6500rpms smooth as silk..

 

X 2 on the coolant level, sleeper and I are both thinking the same thing...the classic HHR low coolant gurgle when cold.

As for the 2.4 sounding rough, mine sounds just like the 2.2's in the other two that I own, smooth as silk with a nice growl. Check the flexpipe from the exhaust manifold to the converter, you may have a leak that only manifests itself at higher engine speeds.

 

Never would have thought coolant. Ill check tonight. In neutral it revs super smooth, must be an exhaust vibration or something. It kinda sounds like the ticking noise it makes all the time after i shut it off but i guess fast ticking is normal as the converter cools.....?

 

x3 on the coolant mine did it too. The technician saw a little residue on the cross over tube behind the engine, thought I might have lost a little there. 6-8 months later I added another cup or so. No more gurgle.