could have a crack in it that is leaking under pressure
Hot water (engine coolant) expands and pushes its way back into the coolant reservoir.
There could be several answers to that question. The thermostat could be stuck closed. The reservior could be overfilled. The cooling fan may not be working. The radiator could be stopped up.
In a 2007 Chevrolet HHR, the coolant system primarily consists of the radiator, coolant reservoir, water pump, and hoses, which are located in the engine compartment. The radiator is situated at the front of the engine bay, while the coolant reservoir is typically found near the driver's side. The water pump, which circulates the coolant, is mounted on the engine. Coolant hoses connect these components, facilitating the flow of coolant throughout the engine and radiator.
Theres to much water in your reservoir bottle, theres a mark were it should be filled up to, any more and it will flow over.
most likely the sensor in the bottom of the coolant reservoir is gone change reservoirs then see
Check the sensor located at the bottom of the reservoir.
A dirty fuel filter is one possibility.
The main components of a cooling system typically include a coolant reservoir, radiator, water pump, thermostat, and cooling fans. The coolant reservoir stores the coolant fluid, while the radiator dissipates heat from the engine. The water pump circulates the coolant throughout the system, and the thermostat regulates the coolant flow based on temperature. Cooling fans help to enhance airflow through the radiator, particularly at lower speeds.
If you want to simply remove the existing coolant and replace it with new, the procedure is very simple. If the cooling system needs to be flushed, do that first and then follow these steps to change coolant. 1. Uncap the coolant reservoir. Open lower drain plug. It is located on the lower edge of the radiator on the driver's side of the vehicle. Turn the plug several times to open the plug fully. It is made of plastic, so be careful when using any tools to turn it. 2. After the coolant has completely drained, close the drain plug. 3. Pour 50/50 water/coolant mix into the coolant reservoir. It will take a while for the reservoir to empty into the engine cooling system. 4. After adding approximately one gallon, start the engine. This will pull more coolant into the system. 5. Continue adding coolant until the level reaches and remains at the "full" level. 6. Cap the coolant reservoir.
Radiator could be plugged or restricted
Either the vent cap is no longer venting, or the reservoir is overserviced. Just a thought.
Antifreeze, or coolant, is poured into the radiator or the coolant reservoir of the engine. The radiator cap is usually located on the top of the radiator, while the coolant reservoir is a translucent tank connected to the radiator. Always ensure the engine is cool before adding antifreeze to prevent burns or injury. Additionally, check the vehicle's manual for specific instructions related to your car model.