right behind the prop, on the same shaft
The impeller on a 9.8 Mercury outboard boat motor can be easily changed. Remove the retaining bolt. The impeller will come off. Reverse the process to install the new impeller.
The water pump impeller on a 7.5 hp Mercury outboard, is located on top of the gearcase, and is driven by the driveshaft.
What year? It may require special tools.
Synthetic Rubber
You will probably have to drop the lower end of the outboard. Its sound hard but really it is usually quite simple. The pump is nothing more than rubber impeller on a brass collet.
Propeller is external (outboard motor on a boat) Impeller is internal (vehicle water pump).
Change the water pump impeller, they get old and need replacing every 5 years or so depending on wear.
This is how to fix the impeller on a Chrysler 25 HP outboard motor. Disconnect the coupling that's on the outside of the leg, flip the housing and twist in impeller.
What year is Mercury Outboard with serial # 5863149
what does a 1991 mercury 150 outboard weigh
hat year is this Mercury outboard 7.5h.p seal #704818
see this site http://sites.google.com/site/bf50impellernotes/