What causes the abnormal noise in the Mercedes-Benz E300L?
2 Answers
Reasons for abnormal noise in the Mercedes-Benz E300L: Uneven engine cooling: After driving for a period, the engine temperature becomes very high. When the engine is turned off, the temperature of various components decreases, and thermal expansion and contraction cannot occur uniformly. This inevitably leads to gaps between internal metal parts due to cooling contraction, resulting in friction and abnormal noise. Cooling noise from the exhaust pipe: Generally, the temperature of the exhaust pipe during cold idle is around 200 degrees Celsius. Under high load or when the mixture burns in the exhaust pipe, the temperature can be even higher. Therefore, the exhaust pipe also undergoes thermal expansion and contraction, producing abnormal noise. Cooling noise from the three-way catalytic converter: The normal operating temperature of the three-way catalytic converter is between 400-800 degrees Celsius. After the engine is turned off, its operation gradually stops, and the temperature decreases. The internal metal parts then undergo thermal expansion and contraction, leading to abnormal noise.
I've been driving a Mercedes-Benz E300L for three years, and recently I've been hearing a clunking noise from the front when going over speed bumps. It feels like some part has come loose. I asked a few experienced drivers, and they said it might be a suspension issue, such as rust on the front shock absorber top mount or wear on the ball joint, especially since luxury cars like Mercedes-Benz are prone to aging after long-term use. I checked the undercarriage myself and didn't find anything major, but the noise persisted, making me worry it might affect cornering stability and tire lifespan over time. Later, I took it to a repair shop, where the mechanic diagnosed it with professional tools and said the suspension components had developed excessive play, requiring replacement parts. After the repair, the noise was gone. My advice is not to delay if you encounter similar issues—the sooner you fix it, the better, as safety comes first.
