China Naming Network - Eight-character query< - Why after starting the engine, the water temperature is first hot in the upper water pipe and then hot in the lower water pipe?

Why after starting the engine, the water temperature is first hot in the upper water pipe and then hot in the lower water pipe?

First of all, the engine waterway cycle is divided into large cycle and small cycle. How can there be a large circulation and a small circulation? It depends on the thermostat. If you remove the thermostat, the upper tube and the lower tube will be heated together without being separated. Small cycle engine internal and cylinder head cycle. The upper pipe is connected to the cylinder head, so the upper pipe is heated immediately. The main reason is that the thermostat is installed at the buckle of the lower pipe, and the water passes through a small circulation. Then the warm air tank circulates in three links behind the co-pilot glove box. The water pump is connected to the water pipe, the water tank is connected to the water pipe, the cylinder is connected to the cylinder, and the warm air box is connected to the water pump.