DaWhoDat

Hey Guys, I am seeking your knowledge and expertise concerning my 2017 E 400 coupe with 27k miles. I previously owned a 2015 E550 and it was an excellent car but the maintenance near 100k started adding up so I recently purchased the 2017 E 400C. Amongst other things, the 17 E 400C has a rattling noise when I am parked/idle. The noise sounds like it is definitely coming from drivers side under the hood near drive side tire. The other issue I am having is with the acceleration, when I accelerate it makes a noise that sounds like something a loose fan spinning, almost as if a fan is loose and you can hear the metal along with the fan, I only hear this noise if I really get the rpms up, otherwise the noise is not present and it shifts smoothly. When I get the rpms high and hear this sound, the engine feels to bog down and then kick back in. Can anyone shed light on what I may be experiencing? I appreciate your time and help.

Mr. Toad

My 2016 E400 coupe has made an engine-related noise at idle since the day I bought it as a CPO with just 12,000 miles, but I wouldn't call the sound a rattle. It's more like a staccato tick or thump and it comes and goes in cycles. I can predict when a cycle will end by a 2-3 tick/thump sequence that almost sounds like a muffled "bump bump bump" drumbeat, then silence. I brought it to the dealer and, although they heard what I was referring to, they considered it normal. Nonetheless, they made several unsuccessful attempts to silence the sound, including the installation of sound-deadening material on the rigid fuel lines that run all the way to the rear seat. I've just learned to live with it at this point.

I'm sorry that I have no input on your acceleration issue, which I have not experienced.