I know this has been discussed a million times with multiple suggestions. Have a 1275 with the air pump, etc. removed with a frustrating leak at rear main bearing area). Tried everything, with and without PCV valve, vent from time chain cover, several different connections. Even tried Gerard's seal. Strange thing that may trigger a hint is that, while running, there is almost no leak but as soon as I turn it off it leaks a lot and for several hours. Any ideas?