Heavy Duty Truck Haowo T7H440 air-cooled car engine abnormal noise, is there a great god who has the same experience, how to solve it?

The causes of abnormal engine noise during cold start-up are: 1, and the oil can't reach the working temperature; 2. The valve rocker arm is worn, resulting in excessive valve clearance; 3. Due to the continuous accumulation of sludge and carbon deposits, the throttle valve is too dirty.

Solution: 1, clean the throttle carbon deposit; 2. Check whether the battery voltage is abnormal. The reasons for the knocking sound when the cold car starts are: 1, and the exhaust valve of the fuel tank is not easy to use; 2. The fluid in the reflux pump has influence; 3. The internal part of the fuel filter is blocked. An engine is a machine that can convert other forms of energy into mechanical energy, including internal combustion engines, external combustion engines, jet engines, motors, etc.