What is the method for diagnosing valve noise faults?

[AndrewDella]

The method for diagnosing valve noise faults is: Remove the valve cover, let the engine idle, and insert a feeler gauge into the gap between the valve tip and the tappet, testing each one individually. If the noise weakens or disappears when the feeler gauge is inserted into a particular valve gap, it indicates an issue. If the noise reduces but does not disappear after inserting the feeler gauge, use a screwdriver to pry the valve stem. If the noise disappears, it is caused by excessive valve clearance due to wear in the valve stem guide. When the engine ages or when oil circuit faults cause abnormal lubrication system pressure, the engine oil pressure cannot meet the required standard during operation. This prevents the valve tappet from adjusting the valve clearance properly. As a result, even when the engine reaches normal operating temperature, the valves may still produce continuous abnormal noise, indicating a fault. The function of the valves is to input air into the engine and expel exhaust gases after combustion. Structurally, the engine has intake valves and exhaust valves.