Mercedes-Benz C240 loud knocking from driver's side of engine at idle, quieter at higher RPMs with diagnostic indicating distributor issue on Mercedes-Benz C240

Some Mercedes-Benz C240 owners report experiencing a loud knocking sound from the driver's side of the engine at idle, which quiets at higher RPMs, often linked to a distributor issue. This knocking may stem from various factors, including faulty spark plugs, excessive carbon buildup, worn bearings, poor fuel quality, or incorrect fuel octane rating. Owners have noted that distributor problems can lead to improper ignition timing, exacerbating the knocking sound. Ignoring this issue could result in major and costly engine repairs, making prompt attention essential to prevent further damage. It is recommended that owners have a qualified mechanic inspect the distributor and related components to accurately diagnose and address the knocking sound. Regular maintenance, such as checking spark plugs and monitoring fuel quality, is also advised to help prevent these issues from arising.