Hello folks. I have a 2005 c230k 69000 miles and religiously serviced. I have noticed a strange noise in the engine bay that lasts about 2 seconds. It occurs occasionally when starting the car hot, not cold. After driving the car to operating temperature then letting it sit for a a couple hours, when starting, it will make this rumble type sound. It doesn't sound like a metallic noise, more of a rumble or flutter. I have read all the threads about cold start noise and the timing chain. Has anyone heard of this noise during a hot start. I have listened to the timing chain case while the engine is running and there is no abnormal noise from that area. No check engine light on or drive ability problems. No difficulty starting either. I'm thinking that perhaps the timing chain hydraulic tensioner may be bleeding down. Thoughts? Thanks!

 

Thank you for your response. I have driven the car several times today and no noise. Yesterday it made the noise on 2 out of 3 starts only when hot. Do you think it would be worth changing the tensioner?