I am trying to assess if my 2000 740iL OSV is gone, or at least on its way to failing. I have read that if you remove the Engine Oil dipstick that there will be minor vacuum down the dipstick tube, the idle may change or become rough.
My car does have these symptoms. If I place my finger over the top of the tube, I can feel a minor suction, but not anything like what you'd call strong. If I rapidly remove my finger from the dipstick tube, there is a clearly audible sound (from the rear of the motor) like a spring loaded valve acting.
Does a failed OSV also contribute towards premature gasket failure on the rocker covers resulting in oil leaks around the covers?