This is a 2011 Chevy Cruze 1.4 L Eco with 116xxx miles on it.

The other night I made it home from driving about 30 minutes from work and when I turned the car off I heard some noises. I looked under the hood and noticed it boiling at the tank. I did replace the reservoir a few months back due to the fact it had a crack in it and was leaking coolant. Did a flush and when I added new coolant I burped the system as I was told.

Everything has been fine until that night. I let the car sit over night purchased a new cap and checked the car and the coolant level was low so I topped it off put the new cap and took it for a spin. After some time of driving everything seemed good until at one point I came to a stop and I noticed some smoke. I parked and turned it off and seen coolant on the side of the engine That came from the reservoir which was boiling again.

I noticed as well there was some coolant that leaked from the coolant temperature sensors, but was told that wouldn't have a major issue from the guy at Autozone which he was the one who said replace the cap in the first place stating it could be a pressure problem. Also someone recommend replacing the thermostat so I will be changing that as well as the coolant sensor this week and dumping out the coolant and flushing it again but is there anything I should know about this issue?

Could it be something else or is this the symptom of something else? At this point I'm not driving the car I don't want to cause anymore damage. Also I checked the coolant level now and it's almost empty at the tank. Will the coolant level being low have something to do with the boiling?

  • 1
    What temperature is the car operating at? Is the temp sensor showing normal temps and its still boiling over, or is the car actually getting too hot?
    – JPhi1618
    Sep 11, 2017 at 16:45

3 Answers 3


In addition to the other suggestions, it might be a good idea to check to see if there is any coolant coming from the weep hole of the water pump. If your water pump is bad or on its way out, it won't circulate the coolant enough to keep it cool.

  • 110k+ is about due for a water pump/thermostat replacement, if the fans are spinning properly. Right around timing belt replacement, so I bet this car doesn't have one. Mar 27, 2018 at 21:52

There are several possible problems. The leak from the temp. sensors may be drawing air into the system when the vehicle cools, causing hot spots, boiling, vapor when the car is run again. You may have clogs in the radiator in some places, causing it to boil into the reservoir. The coolant/water ratio may be improper, changing the specific gravity of the mixture and thus boiling.


Everything has been fine until that night.

Given the sudden onset of the issue, I'm reluctant to say that the recently-performed work was to blame.

I parked and turned it off and seen coolant on the side of the engine that came from the reservoir which was boiling again.

The coolant is clearly hotter than what it should be, which could be due to:

  • lack of heat rejection from the coolant

    Things that typically cause this are inoperable radiator fans or a clogged radiator.

  • lack of temperature control

    This usually is the result of a stuck-closed thermostat.

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