Here are a few reasons why the overflow bottle might be boiling hot:
1. Excessive Pressure: If the pressure in the cooling system becomes too high, it can cause the coolant to boil at a lower temperature than normal. This can happen due to a faulty radiator cap or a clogged pressure relief valve within the cooling system.
2. Coolant Leak: A leak in the cooling system, such as a damaged radiator hose or a faulty water pump, can lead to a loss of coolant and cause the remaining coolant to overheat. As the coolant level drops, the temperature in the system increases, causing the coolant in the overflow bottle to boil.
3. Malfunctioning Thermostat: A stuck thermostat can prevent the coolant from circulating properly, causing the engine to overheat and the coolant to boil in the overflow bottle.
4. Faulty Radiator Fan: If the radiator fan is not functioning correctly or is obstructed, it won't be able to dissipate heat effectively, leading to overheating of the coolant and boiling in the overflow bottle.
5. Air in the Cooling System: Air pockets or bubbles trapped in the cooling system can cause localized hot spots and result in boiling of the coolant in the overflow bottle.
It is crucial to address the issue as soon as possible if you notice that the overflow bottle is boiling hot. Overheating can cause serious damage to the engine and other components, such as head gasket failure, warped cylinder heads, or even engine seizure.
If you have limited knowledge about car maintenance, it is recommended to take your vehicle to a qualified mechanic or service center to diagnose and resolve the underlying problem before further damage occurs.
