Over heating/ coolant boiling into the overflow reservoir?

2013 CHEVROLET CRUZE
115,000 MILES • 1.4L • TURBO • AUTOMATIC
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GSCHEPKER03
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I have a 2013 Chevy Cruze 1.4L turbo and I’m looking for some diagnostic advice on an overheating/cooling system issue.

The problem started after I noticed a small coolant leak under the car. I traced it to a hose connected to the thermostat housing. I cut the end of that hose back a little, reattached it to the thermostat, tightened the clamp, and added coolant. After that I took it on a short drive to the store and it seemed fine.

Later that night, my mother drove it to the gas station and on the way back it overheated and gave an overheat warning on the dash. She pulled over, let it cool down, and then limped it back home. After that the car sat for a while and I didn’t get back to it until last week.

So far I’ve replaced the thermostat and the coolant reservoir cap. After that I took it on another short drive and noticed the radiator fan never kicked on at all. While driving, it set code P0480, which points to a cooling fan relay/control circuit malfunction. I tested replacement relays at O’Reilly and the fan still would not come on.

Current symptoms:

- Coolant is still bubbling/boiling into the overflow reservoir once the engine gets fully warmed up
- Cooling fan is not turning on at all
- Temp gauge on the dash is reading normal
- Boiling/bubbling doesn’t start until the engine is fully warm
- Oil does not appear milky
- Exhaust looks normal and I’m not seeing thick sweet-smelling white smoke

I already have a radiator fan assembly on the way and it should be here this week, but before I keep throwing parts at it I wanted to ask what you’d check next. Does this sound more like a failed fan assembly/control issue causing the overheating and coolant boil-over, or should I also be concerned about something else like air trapped in the system, poor coolant circulation, or a possible head gasket issue even though the oil/exhaust don’t currently point that way?

Also, based on these symptoms, would you consider it unsafe to drive until the fan issue is resolved and the cooling system can be tested further?

I’m mainly looking for help and ideas because I really can’t afford to take it to a mechanic right now, so I’m doing all of the work and diagnosis myself.
Jul 7, 2026 at 1:55 PM
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STRAILER
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It might still have a blown head gasket without the sweet smell or the coolant going into the engine oil. Before you go any further I would do a chemical test. Please go over this video and guide to will let us know what is going on.

https://www.youtube.com/shorts/0cCln2hgjKA

and

https://www.2carpros.com/articles/head-gasket-blown-test/

The exhaust gasses can get forced into the cooling system which gives you the bubbles, it could be the cooling fan stopped working and caused the issue. Also, the replacement cooling fan is a good idea as well, they go out. Thank you for the detained question it helps.
Jul 7, 2026 at 6:16 PM
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