I'm sure donbrew will agree with this.........

If you are having this problem recently the coolant should be checked more frequently. Like every day .....cold and hot engine !!

 

Okay. I am with Snoop on the head gasket, but it could also be a valve stem leak.
Here is a cut and paste from Wiki:

If the exhaust billows white smoke for a few seconds when first starting the engine after it has been sitting for a while, such as overnight, and then runs normally, it could mean that the rubber valve stem seals have perished - especially if the vehicle is a few years old and has done over 60/70,000 miles. Another clue is: does the exhaust smoke smell like fresh, rather than burnt oil.
After going nuts trying to figure out sporadic tailpipe smoke on my Nissan Maxima, with no other negative engine symptoms, I eventually stumbled upon a malfunctioning PCV valve. The ball-check wasn't fully seating, allowing small amounts of oil to sneak past and into the combustion chamber. A cheap and easy fix.

Check these two things.....and check your oil for brownish liquid. (head gasket)
I hope that it is an easy one.....

 

I have heard of it as an excuse not to check anything else for free, they will only do so much for free, gotta make a living. The catalytic converter does indeed produce some water vapor, but it goes out the pipe unseen. You are describing a lot more than that.


And I absolutely agree; check the coolant level daily cold and hot, and I would also add look at the top radiator hose when it's cold, if it is collapsed you have problems. Also I would remove the pressure cap when cold to make sure there is coolant in the system, it should fill the top hose.

 

That isn't something I have heard of - however if your HHR is used primarily for short drives, it is possible that the exhaust system may not get fully up to temperature and could leave some moisture in the exhaust. That moisture will then be driven out on a longer drive. Volvo's from the mid-70's were famous for that, rotting out the exhaust pipes and mufflers every 2 years or so.

However, you mentioned that the coolant level is checked every 3 months at oil change time - if you are noticing white smoke/vapor out of the tailpipe, and a head gasket is suspected - you would definitely want to check the coolant more frequently than that. If it was me, I'd be checking it before every drive, and tracking how much coolant needs to be added.

Donbrew had it on the money with his comments, as did Snoopy.

 

If you recall from high school chemistry, when something is burned, the products of combustion are water vapor and carbon dioxide. When the exhaust system is cold, the water vapor condenses in it. When you start driving, the exhaust system heats up just enough to turn the water to vapor again but as it exits the tailpipe it cools rapidly in the air and condenses into a white cloud like your breath does in cold air. After you drive for a distance the exhaust system heats up and the vapor is warm enough so it will dissipate in the air before it cools so it isn't as easily seen. If the air temperature is colder, the cloud will last longer and if the air is very damp the cloud will be seen longer. The exhaust is cooled in the car wash and the car wash is damp, hence the cloud showing up there. Here in Wisconsin, when the temperature is below 0, the cloud shows up several feet behind a car.

If it is losing coolant, it would likely show up by now. There is a chemical test to check for combustion products in the coolant.

 

You know, the more I thought about this, the more I believe there is nothing out of the ordinary happening. In other words, Don06 is correct. It is just condensation "burning" off.

Especially after rereading the OP's original post, ".....from time to time...." and "....about two months ago." If she was experiencing a mechanical failure of some kind, it would, in most instances promote the smoking traits all the time. And if it was the head gasket leaking, further engines difficulties would have appeared by now.

So, to LadyI953 I would say, don't worry about what you observed. Read Don06's explanation. I think he is right on.

 

All depends on temperatures..and how warm the car is..on extreme days Im sure youve seen other exhausts pouring out white, though normally it should go away after a ffew minutes as everything warms up..if you keep seeing it, especially on warmer days then you have a possible problem. Since your cat converter converts parts of the exhaust to water its normal to see some from the tail pipe. So watch your water temps and fluid levels, if they stay normal then I wouldnt worry.

 

well just my 2 cents but since we have a new Pope and taken that off the list for the cause of the white smoke , then check the coolant level over a peroid of two to three days, if it goes down have the mech do a leak down test on the cooling system and a compression test on the engine, for me the compression test revealed the issue was a head gasket and turned out a small crack in the head between #2 and #3 cylinder, most likely because I didn't notice the issue for a week or so.

 

Thanks Don06, Snoopy and IgottaWoody. I think you all are right. I took my HHR to City Chevolet and they told me that my engine had sludged up. It was to cost me $750 to $800 for them to flush my engine. So I got a second opinion. I took it to another mechcanic kept my HHR for two days checking it out. He told me that their was nothing wrong with my engine because he checked. He said he did see a little white smoke when he drove it. He stated, that it is mositure and there is nothing to worry about. All my gagues are working properly. There has been no lights coming on to suggest that anything is wrong with the engine or anything else. Anyway City Chevolet charged me $87.00 after I told them, once I get the money I will bring my car back. The other mechcanic did not charge me anything. Go Figure!!!!Thanks everyone for your advice. I am glad it was not a head gasket blown......LOVE MY HHR.........

 

Congratulations, you have found an honest mechanic! Give him your business and tell others. I would hope someone from Chevrolet reads this thread and consults with City Chevrolet.