Review on 🔩 Gates 38319 Automatic Belt Drive Tensioner with DriveAlign Technology by Savoeun Ramirez

Swapped for my 2012 C300 and fits perfectly. When I removed my OEM original it was also marked "Gates". So my guess is that Gates is an OEM and a direct (read: cheaper) replacement without the Merc markup. With some mechanical experience it took me about 2 hours (remove the old one and install the new one). You should probably change the belt as well, I got the Gates version here on Amazon and it worked great. Also, there is a great YouTube video (search QY4Gp11G5tI) documenting the exchange, including the serpentine diagram. Please note that you will need some special tools like Torx E12 (female). If you are replacing an existing tensioner you will need some sort of pin to lock the old tensioner in place so you can remove the belt and pull out the old block. As you can see from the video, the old 3/16 hex wrench works great. The new block comes with a pin, but you must leave it on during installation.