2015 Sonic LS Smoking Up

[Delivery123]

I've got a 2015 Sonic LS currently sitting at about 108k miles. Around 105k, an hour into a two hour drive, I looked out my rear view and couldn't see anything behind me due to thick smoke. I pulled over, threw my hazards on, and waited for a tow. A friend of the parents drove it around for a week with no issue, so it was given back, but sure enough a day later it smoked up again. This happens two more times in the span of about a week, and then once again a month or so later. Each time this has happened, it's been accompanied by a loss of engine power and what feels like a rough idle. The smoke is either white or light grey.

I brought the car to a mechanic and had them run a coolant system pressure test, which came back all clear, so thankfully it isn't something like a head gasket, but I drive delivery for a living and can't afford to have my vehicle out of commission.

Other issues with the car currently include an intermittent P0420 code, and I know I need to replace my spark plugs, but other than that it's been a great ride. If anyone has any idea what might be the issue, I would really appreciate it.

 

[TheGreenDragon]

Intermittent problems are the worst. It just means the issue hasn't gotten bad enough where it's happening all the time but is a pain in the butt to reproduce.

The fact that you are noticing a loss of engine power and rough idle in combination with the white smoke means your engine is burning something that isn't combustible; most likely coolant.

I know you've taken it to a mechanic who ran a pressure test but if the problem really is intermittent it might not be so easy to find. The best thing I can tell you is to get a second opinion. But before you do, take super detailed notes about the exact conditions that result in the white smoke; specifically how long the car is driven/how far it is driven/how hard it is driven before the smoke shows up. Document the coolant level in your tank before and after every drive. Even if the car isn't visibly smoking it could still be consuming coolant in small doses.

My guess is you might have a cracked engine block where the crack expands and lets coolant through once the engine is warmed up but not when it is cool.

 

[brainpause]

I've got a 2015 Sonic LS currently sitting at about 108k miles. Around 105k, an hour into a two hour drive, I looked out my rear view and couldn't see anything behind me due to thick smoke. I pulled over, threw my hazards on, and waited for a tow. A friend of the parents drove it around for a week with no issue, so it was given back, but sure enough a day later it smoked up again. This happens two more times in the span of about a week, and then once again a month or so later. Each time this has happened, it's been accompanied by a loss of engine power and what feels like a rough idle. The smoke is either white or light grey.

I brought the car to a mechanic and had them run a coolant system pressure test, which came back all clear, so thankfully it isn't something like a head gasket, but I drive delivery for a living and can't afford to have my vehicle out of commission.

Other issues with the car currently include an intermittent P0420 code, and I know I need to replace my spark plugs, but other than that it's been a great ride. If anyone has any idea what might be the issue, I would really appreciate it.

Did you ever find out anything? Sounds sorta similar to my issues.

Larry