Mercedes-Benz released the 9th generation of their E Class, the W212, at the Geneva Motor Show in 2009 and began selling to consumers in 2010. The car included a bundle of luxury features, such as Night View Assist Plus, Lane Keeping Assist, and Pre-Safe with Attention Assist. Some W212 owners experience a starting noise or a rattling sound coming from the engine.
The sound can be best described as a wooden rattling or clicking. Some owners claim that it is very loud, some say that it is quieter, but it always begins shortly after the car is started if the car is started cold. The rattling only lasts for a few seconds, between three and four, and then it completely dies away. Owners also say it does not happen every time they start their car cold, making it hard to pin down and show to a mechanic. What is consistent from owner to owner is the sound itself, which rises prominently above the growl of the engine.
Sometimes, this sound is a completely normal result of cold oil being pulled into the engine, but it could also indicate that there is poor oil circulation due to clogged lines. There is also a chance that the timing chain needs to be recalibrated or replaced. Most often, the sound is simply due to the hydraulic lifter that is employed to make the direct injection system function correctly. Regardless, it is worth paying attention to and trying to sort out.
This is why we highly recommend taking your W212 over to a nearby Mercedes-Benz repair technician who is highly experienced in identifying and solving all sorts of issues similar to the one you may be experiencing. Taking your car to a professional will ease your mind and return your faith in your vehicle.
Search for a local, independent Mercedes-Benz repair shop with Mercedes-Benz mechanics that have dealer-level expertise at a fraction of the expense.