关键词: 轻型卡车；整车水温偏高；分析验证；整改验证；优化设计

Abstract: In order to find out the reasons of the high coolant temperature performance of a light truck, combined with customer vehicle driving status and test on chassis dynamometer, comparative testing using the hub test method with precise control of boundary conditions. Analyzes the difference between engine load, fan state and thermostat state. The conclusion is that the thermostat can not be turned on in time in winter. Through simple on-site measures, the water temperature of the fully open thermostat was verified, and it was determined that the vehicle thermostat could not be opened in time in winter, so that the water temperature gauge indicated that the water temperature in winter was higher than that in summer. This conclusion can provide test support for engine product development, and remind the engine development process to pay attention to the verification of the timing of the engine thermostat opening under low load conditions.

Key words: Light truck; High coolant temperature; Analyses; Test support; Low load condition