I am seeing substantial blow-by on a 190e 2.3 78k engine. It is suggested that it could be valve seals. piston rings (stuck) or pcv unit. Does anyone have information or guesses as to what and where to check for the most likely causes for a 78k engine. I will say that the blow-by from an open oil cap will give you a new hairdo or g-force experience. The engine seems to have plenty of power although with intermittent rough idle which I have attributed to a relay or sensor somewhere . No engine smoke or exhaust problems other than the suspicion that my cat converter is restricted. All is too new looking for any real problem if that is of any criteria.