Frozen Engine Blocks Cause Overheating | Joe & Tony’s Service Inc.
Unfortunately, it happens that car owners dilute their cooling systems by adding water to the coolant reservoir or directly to the radiator over the warmer months. This can happen when a hose is replaced or by mistakenly topping off the system with water instead of coolant.
When this occurs the cooling system becomes vulnerable to freezing up during a sudden dip in the outside temperature. Most systems should be protected to minus 20 degrees Fahrenheit to avoid this from happening. The strength of the anti-freeze/coolant can be checked with a hydrometer made for this purpose or a repair shop can check it.
Surprisingly, the symptom of a poorly protected cooling system that has become frozen is for the car to overheat. The reason for this is that the ice in the engine block or radiator is blocking coolant flow and as a result the engine temperature rises rapidly to a dangerous level.
The only real solution to this condition is to remove the frozen vehicle to a warmer location and very slowly warm it up. Then the vehicle can be started and very closely monitored as it approaches operating temperature and the thermostat opens.