That seems a long
time. While the outboard is running, its waterpump impeller is spinning
and pulling water up into the powerhead for cooling. There's no
auto-type radiator in an outboard, so where would all that water being
pumped up into the powerhead be stored?

hi harry, there are other 'pee holes' in the gear unit before the water gets
to the powerhead, so the water can keep flowing regardless of whether it's
flowing through the powerhead or not...
andy