I've got a California version OM617.952 in my 107 and since I completed the swap, I've been just dumping the raw valve cover vapor directly into the air intake just ahead of the turbo. Unlike earlier cars that have a separator that returns oil to the sump the later ones just dumped everything into the intake. Having cleaned out the intake and not wanting to do that job again, I decided to fabricate a catch can to strip out the oil from the vapors.
I've seen quite a few methods but decided to try something of my own design.
I created a mock up using cardboard to fit the space I had between the existing brackets in the engine bay. I cut and welded the box. (I was going to go use the brake but decided to use the old vice and hammer trick) Before welding on the cover, I welded in female 1/4 NPT fittings using steel air hose fittings with the barb cut off.
I filled the cavity with stainless wool to provide a good substrate for the oil to condense out on. By having the intake and exhaust on opposite ends the vapor will have to transit a good 6 inches of stainless wool that should do a pretty good job.
Here's the completed custom catch can ready to be installed.
And here is the finished product installed in the car.
My 617 has an early "smooth" pan upper oil pan, (that I needed for subframe clearance) and that has the check valve for returning oil to the sump, so I was able to just use the original oil return line for my catch can drain line. This drain line exits the bottom of the catch can at the lowest point.
I'm anxious to see how well this works, but certainly it can't be any worse that the original setup. And without the EGR my intake and turbo should be quite clean moving forward.