Mercedes-Benz water temperature is unstable and stable. What is the reason for the fluctuation of Mercedes-Benz water thermometer?

Our general understanding is that when driving normally, the water temperature can remain unchanged when it rises to about 90℃, but the water temperature meters of many Mercedes-Benz cars are fluctuating. "The water temperature suddenly dropped from 90 to 80, and then returned to 90. Especially when driving at a high-speed fuel filler, the water temperature will change between 90-80. " I thought there was something wrong with our car when we first met. I know this car, so I want to express some opinions here. Viewpoint: Don't worry, this situation is often normal. Equipped with three-stage electronic thermostat, it can adjust the coolant temperature at each working position according to requirements (engine load, sensor parameters, etc.). I think the water temperature varies between 90 and 80, but the thermostat is in the comprehensive circulation position. The thermostat is turned on and off as needed, and the water temperature changes accordingly. I wish the water temperature didn't stay at 80 for a long time. (Mercedes-Benz coolant working circuit details 1, no circulation) Fully closed)) During cold start in fully closed position, the three-piece thermostat does not work, and the coolant circuit is closed. The static coolant is heated rapidly, and the heat is transferred to the oil through the oil heat exchanger in front of the engine. When the coolant temperature is about 70 or 45 (the outside temperature is about 12), the temperature is controlled, and the thermostat is switched from the fully closed state to the short-circuit working state. In addition, the valve plate closed from 3500 rpm is opened under the pump pressure. 2. Small cycle (short circuit operation) When the coolant temperature is around 70 or 45 (the external temperature is above 12), the control mode is switched from no cycle to short circuit cycle. In the engine warm-up stage, gradually open it until the pipeline connecting the pump is completely opened. During the short-circuit cycle, the engine and heat exchanger can be adjusted. 3. Comprehensive circulation position Once the engine is fully warmed up (the coolant temperature reaches about 98 after the engine is started), there are two circulation modes: at partial load, adjust the coolant temperature to about 100 with a three-piece thermostat. In order to prevent the occurrence of critical temperature, the heating range of coolant temperature is about 90 (the outside temperature is lower than 12) or about 80 (the outside temperature exceeds 12), the engine speed exceeds 3000r/min, and the intake temperature exceeds 38. This is the control principle that the water temperature drops to 80 when many car owners accelerate at high speed. 4. Large cycle (radiator working) position During the radiator working, the thermostat works continuously. When the temperature is higher than about 1 10, the three-piece thermostat is always in the full open position and is not controlled by work. Electronic thermometer resistance: 15.2 1.5.