1、 Insufficient or leaking coolant
When the car is cold, open the filler cap beside the radiator and check whether the coolant is sufficient. The coolant shall be replenished from the filling port at idle speed, and the coolant in the reservoir shall only be replenished to about 2/3 of the total capacity. Check whether the engine oil is emulsified and deteriorated. If the oil becomes white, it indicates that the coolant is leaking. The engine must be disassembled to find out the cause of the internal leakage and eliminate it. Generally, internal leakage mainly occurs at the joint of cylinder head and cylinder block, which can be solved by replacing the cylinder mattress. The proportion of the coolant varies with the area of use and the concentration of the stock solution. In addition, carefully check each water pipe joint for dirt leakage, water pipe for damage, and water pump leakage hole for water leakage.
2、 Blockage of circulation system
Check the circulation system for blockage. The radiator shall be cleaned with water tank cleaning agent every 5000km, and special attention shall be paid to whether the small circulating water pipe is twisted. Because if the small circulation is not smooth, after the engine starts, the temperature of the coolant in the cylinder head water jacket of the cylinder block increases continuously but cannot circulate, the water temperature at the thermostat cannot increase, and the thermostat cannot be opened. When the water temperature in the water jacket rises above the boiling point, the water temperature at the thermostat gradually rises with the intensification of molecular movement, the thermostat opens, and the high-temperature and high-pressure water in the water jacket rushes out of the filler cap, causing "boiling".
3、 The valve clearance is too small
In order to ensure the engine performance, there are certain requirements for the valve clearance, not the smaller the better. Because the size of the components of the domestic engine is out of tolerance or the user does not accept the valve noise, many domestic manufacturers adjust the engine valve very small when the product leaves the factory, causing the valve to not close tightly, which may extend the afterburning period of the mixed gas combustion, and most of the heat generated during the afterburning period is used to do work for heating, thus causing the engine to overheat. In fact, as long as the valve clearance is adjusted as required, slight valve noise will not affect the use.
4、 Mixture concentration is too thin
Generally, when the carburetor leaves the factory, the mixed gas concentration has been adjusted by professionals with special equipment, and Moloto does not need to adjust it. If it is determined that the overheating is caused by too thin mixture concentration, it is necessary to adjust the carburetor adjusting screw appropriately.
5、 Poor operation of thermostat
The role of the thermostat is to reduce the amount of coolant circulation after the cold start, so that the engine can reach the optimal operating temperature (about 80 ℃~95 ℃) as soon as possible. The authentic wax thermostat should start to open when the coolant temperature is about 70 ℃. If the thermostat cannot be opened normally when the coolant temperature is about 80 ℃, it will inevitably lead to poor circulation and overheating of the engine.
Post time: Dec-08-2022