M156 (C63) making a loud high pitched noise
A few weeks back I got my first M156 in the form of a C63 (2014) with just around 40k kilometres (~25k miles). It has only driven maybe 25 kilometres (~15 miles) after buying - to a warm garage and then after a couple of days from there to a different parking space. During the initial test drive (before buying) and these two drives everything seemed totally fine. However, after sitting in the second parking space (under a roof, but outside in around 0°C or 32°F) for a week I started the car and at first didn't pick up on anything weird and went inside to let it run for a bit. After a few minutes I go outside and hear a loud high pitched noise (video attached) coming from the engine bay. Has anyone had a similar issue or knows what this could be?
Thanks!
Last edited by ranc; Jan 3, 2023 at 11:11 AM.


