Is this a sign of a clogged crankcase ventilation system? The picture is from a 2005 X3 3.Ol with 108K. I've noticed no white smoke when cranking, but it does occasional idle slightly rough.
Crap in there... There is always some crap in the system since it is supposed to draw volatile stuff out of the crankcase and into the combustion chambers to be burned up. As the engine wears it allows more blow by gasses into the crankcase and some of the stuff condense inside the system. The only real way to check is with suction and pressure (ie your mouth) to see if the valve is functioning properly. Find a piece of clear plastic tubing that fits snugly into that opening. Then remove the oil filler cap. Now test by providing suction and the valve should open and allow some air to flow through, test by blowing into it and it should close preventing air from flowing in. If it does not allow air flow either way then it is probably clogged. If it allows ample air either way then it may be stuck open. If it seems to perform its function "poorly" then it is a judgement call. You can put the oil filler cap back on and check the system for leaks if you are so inclined to "draw it down" if possible. If the valve is easy to get at then it might be best to just replace it. This information is not specific to BMW, but rather to all EGR valves. Some can be cleaned by soaking them in a suitable solvent and then blowing them out with an air jet. The problem is that "suitable solvent" may be hard to determine if the housing or components contain plastic. Kerosene is one of the best solvents I have found for oils, sludge, etc, and doesn't affect most plastics. Chuck
