540i oil separator tip (behind the chain guide)
This is for those whose rear intake manifold covers (CCVs) keep clogging up with oil.
Since I'm having to replace my timing guides anyway, I'll be swapping out the oil separator for a new one, but... there is a fix for those that don't need to pull their timing guide rails. The part of the oil separator that fails is the bit of (ridiculously brittle) plastic hose which connects the main body of the separator to the outlet (which accepts the pipe that runs underneath the intake manifold to the rear manifold cover). The outlet is held in place by a small bolt on the center guide rail, and if the plastic hose is already damaged, it will come right out when that bolt is loosened. The rest of that plastic hose is very easy to knock off, and can be replaced with appropriately-sized high temp rubber hose from an auto parts store. It's a bit difficult to get in there, and I ended up having to grind down the hose, both on the outside and a bit on the inside edges to get the hose to slide over the nipple on the main body of the separator. You won't be able to clamp it, but assuming the hose is sized right, there's no way for it to come off, because it is a very short length running between two parts that are jammed in place.
I'll post a pic of the old separator as fixed next to the new part once I have it out of the car this weekend. Although it's a pain, it's not nearly as bad as pulling the timing rails and the lower timing cover. And I suspect the rubber hose could outlast the plastic hose by a wide margin.