A lot of good gear oil gets thrown out.----No need to change it often if seals are keeping the water out.----If water is getting in you need a complete seal kit !!
???-----Poppit valve must open at higher throttle settings.----These 3 cylinder motors have enuff cooling issues already.----Do not ignore a leak there !
There is a vent hole in some covers.----It allows the poppit diaphragm to move.----If water leaks out ,the diaphragm has a hole or is not sealed properly.