Lexus GS350 loud knocking noise in the motor on Lexus GS350

Some Lexus GS350 owners report experiencing a loud knocking noise in the engine, which may indicate engine knocking caused by an improper air-fuel mixture. This knocking can resemble marbles rolling inside the engine, particularly in severe cases. Additionally, other owners have noted that improper fuel octane, carbon buildup in the combustion chamber, or incorrect ignition timing can also lead to knocking or pinging noises. If the knocking is more pronounced at the bottom of the motor, it may signal a serious issue that could necessitate a new engine block. Some owners have observed that the knocking noise is more noticeable when the engine is cold, but it can persist even after warming up. It is recommended that owners have their vehicles inspected by a qualified mechanic to diagnose and address these potential issues promptly.