- A faulty thermostat may also lead to coolant bubbling in the reservoir.
- When the thermostat fails to open properly or at the correct temperature, the coolant becomes trapped within the system, overheating, and causing the coolant to bubble.
2. Blown Head Gasket:
- A blown head gasket can introduce combustion gases into the cooling system.
- These gases may cause the coolant to bubble, appear discoloured, and emit a sweet smell.
3. Faulty Radiator Cap:
- A faulty radiator cap that doesn't hold or release pressure as intended can cause the coolant to boil and bubble.
4. Air Pockets:
- trapped air pockets in the cooling system can cause the coolant to bubble.
5. Engine Overheating:
- If the engine overheats, it can cause the coolant to boil and bubble in the reservoir.
