What are the hazards of a faulty thermostat?

[DeJackson]

The hazards of a faulty thermostat to a car are as follows: 1. A faulty thermostat can cause the cooling water temperature to go out of control. When designing the cooling system, the maximum heat dissipation capacity is based on ensuring reliable cooling for the engine under the most challenging conditions, such as high load, low speed, and high external temperature. Obviously, under conditions of low load, high speed, and low external temperature, the heat dissipation capacity is excessive, causing the engine to overcool. Therefore, a device to regulate the cooling intensity is needed, achieved by changing the air flow of the radiator or the cooling water circulation route, ensuring the engine operates within the most suitable range. The change in the cooling water circulation route is generally automatically controlled by the thermostat based on temperature changes. When the cooling water is below 70°C, the cooling water circulates in a small loop without passing through the radiator; when the cooling water temperature is above 80°C, it circulates in a large loop through the radiator. 2. A faulty thermostat causes drastic changes in the engine's economy and durability. Without a thermostat, the engine often operates in a low-temperature state, leading to poor thermal conditions, accelerated wear of components, and increased fuel consumption. Experiments show that when the engine operates at low temperatures of 40°C~50°C, its wear increases by 30~40 times, significantly shortening its service life. The reasons are: (1) Increased fuel consumption: Due to the low temperature, excessive heat dissipation from the cylinder walls reduces the temperature and pressure of the gases in the cylinder and thermal efficiency, leading to increased fuel consumption. (2) Increased wear of parts: Poor evaporation and atomization of fuel make it difficult to form a proper air-fuel mixture, causing the mixture to become too rich, incomplete combustion, and a large amount of fuel to be wasted without effective use. This results in reduced power, increased fuel consumption, and in severe cases, some fuel in the mixture condenses on the cylinder walls, washing away the oil film and flowing into the crankcase, diluting the oil and increasing part wear. (3) Reduced engine power: At low temperatures, the viscosity of the lubricating oil increases, and its fluidity deteriorates, increasing the resistance of moving parts such as the crankshaft and bearings, and the piston and cylinder walls, leading to reduced power and increased fuel consumption. (4) Corrosion effect: Water vapor produced by combustion condenses on the cylinder walls at low temperatures and combines with combustion byproducts to form strong corrosive agents, such as sulfuric acid, nitric acid, and carbonic acid, which strongly corrode parts like the cylinder walls, pistons, and piston rings.