Without a GM Thermostat, what adverse effects might occur on the engine's operating temperature and performance?

Overheating: One of the main functions of a GM Thermostat is to allow more coolant to flow through when the engine temperature is too high to reduce the temperature. Without a thermostat, the coolant may continue to circulate at maximum flow, but in some cases, this may prevent the engine from quickly reaching and maintaining the optimal operating temperature. When running at high loads or speeds, without sufficient coolant flow increase, the engine may overheat, which may damage components such as seals, gaskets and bearings, and even cause deformation of the engine block or cylinder head.
Reduced fuel economy: Running the engine at too high or too low a temperature will reduce fuel efficiency. In the cold engine state, fuel requires more energy to evaporate and mix with air to form a combustible mixture. However, due to the low engine temperature, the fuel evaporates more slowly and the mixture is not formed evenly, resulting in some fuel not being fully burned and discharged, thereby increasing fuel consumption. In addition, when the engine is cold, more fuel is required to maintain a stable idle speed and acceleration, which further exacerbates the fuel consumption problem. Lack of a thermostat may cause the engine to run too long in a cold state and fail to reach the optimal operating temperature in time, which will continue to affect fuel economy.
Emissions: At too low or too high temperatures, the combustion process of the fuel may be incomplete, resulting in a large amount of unburned or partially burned fuel entering the exhaust system. These incompletely burned fuels will react with oxygen in the air at high temperatures to produce harmful gases such as carbon monoxide (CO) and hydrocarbons (HC). At the same time, high temperatures will also cause nitrogen in the air to react with oxygen to produce nitrogen oxides (NOx). These harmful substances not only pollute the environment, but may also harm human health.
Increased engine wear: Metal parts inside the engine will be subject to additional wear at too high or too low temperatures. For example, overheated engine oil will lose its lubricating properties, resulting in increased friction between internal engine parts, thereby accelerating wear. Overcooled engine oil may not be able to effectively cover all lubricating surfaces due to poor fluidity, which will also cause wear.
Poor driving experience: Due to large fluctuations in engine temperature, its output power and torque will also change accordingly, resulting in unstable vehicle acceleration, idle jitter and other phenomena. In a cold engine state, the engine needs more time to reach the optimal operating temperature, so its power output will be limited. In addition, overheating may also cause the engine power to drop, because measures such as delaying the ignition time or reducing the compression ratio to prevent knocking will reduce the engine's output power. In cold weather, an engine without a thermostat may take longer to warm up and reach the normal operating temperature range. This can cause problems such as difficult cold starts and unstable idle speed after starting.
The thermostat is an indispensable component in the engine cooling system. It ensures that the engine operates within the optimal temperature range by precisely controlling the flow of coolant, thereby protecting the engine from damage, improving fuel economy, reducing pollutant emissions and improving the driving experience.