Mercedes-Benz C300 grinding noise on startup resolved by replacing chain tensioner on Mercedes-Benz C300

Some Mercedes-Benz C300 owners report experiencing a grinding noise on startup, particularly during cold starts, which may be linked to the chain tensioner. This grinding noise can be attributed to oil circulation delays or worn timing chains, resulting in improper oil flow through the engine. Additionally, some owners note that the noise resembles metal parts grinding, potentially indicating that the starter teeth are not fully engaging with the flywheel teeth. In certain driving conditions, such as making sharp right turns after a cold start, the noise may also appear. It is crucial for owners to ensure that the starter engages fully to prevent damage to components like the flexdisc and starter gear over time. If the grinding noise persists, it is advisable to have the chain tensioner inspected and possibly replaced to effectively resolve the issue.