205 while stopped in traffic would not concern me, 208 at 60 mph would raise an eyebrow.

As with almost every front drive vehicle, our Trucklets depend on Ram-Air for cooling until you're stopped or creeping along.

At that point, the electric cooling fan should kick on at 217 degrees and drop the engine back down to somewhere in the 187-188 degree range in about 45-60 seconds or less.

All good replies above, and I'm thinking that a reflash of the ECM to reflect the 2.2 to 2.4 swap out is most definitely in order.

As to what a "normal" range is, I've got four HHR's, and "normal" on one doesn't translate to its siblings. My normal ranges are 188-192 on one, 196-200 on another, 187-191 on the third, and the fourth one has been disassembled for 15 months...so its normal will depend on how the freshly built L-61 engine settles down after its break in period.

The analog gauge is semi accurate, but it's mainly there to balance out the instrument cluster.

 

I wish the analog temp gauge was an oil pressure gauge instead or maybe a volt meter!

And the original engine and the replacement engine are both 2.4's right!

 

Mike I was confused, too. I am pretty sure that it was a 2.4L to 2.4L swap.

 

I still believe the stat is the culprit!!

 

Sorry I dont understand, please elaborate. I feel that 208° is too hot for the engine to run while cruising down the highway on a day that the outside temp is 77°. Do you feel that the temp is acceptable?

 

Clarification, the original engine was a 2.4L (LE9), the replacement engine is a 2.4L(LE9) out of another 2009 HHR with 33K miles from a junkyard.

When we pulled into the driveway, I popped the hood (with the engine running) and inspected for any coolant leaks and the fan was running. I then turned the ignition off in which the fan immediately turned off. I thought that was strange, since my cavalier lets the fan run for a while with the engine off.

yes I do have the 1.5" black strip across the bottom that deflects air up toward the radiator.

I have ordered the lower radiator hose and the thermostat, both AC Delco brand.

This cool morning, I took my digital meat thermometer and stuck the probe into the radiator fluid and it read 71.8°, I then turned on the ignition (not starting the car) and the temp on the DIC reads 72°. I suspect the coolant temp sensor is right on.

 

I am using the green coolant. I see you are talking about DexCool. Is this really important, if so I will drain it and refill with DexCool whenever I change out the thermostat.

 

I personally use the fluid the manufacturer recommends in this case Dexcool 50/50 mix!!

 

So exactly what water do you MIX with your dexcool. The HHR owners manual says drinkable water, but at the GM plant that I work at we have a huge RO/DI filter to mix in with it. Most people on the internet say use distilled water, since tap water has minerals that are destructive to the block. I have always been confused with this. Maybe the water type does not matter?

 

If you are going to be haunted by the water, just buy Ready To Use. Personally I use tap water. But opinions are like belly buttons.