Good morning. Question: Do I need to drain the gear case (I just changed the lube a few days ago) and undo the shift rod if I’m just rebuilding the water pump?
In theory you should not need to drain the gear-case..... provided the drive shaft pulls easily from the crankshaft and stays in position in the lower unit.
You do have to disconnect the joint between the upper and lower shift rods.
As said above you should be looking for a telltale "pee stream" from the hose coming from the exhaust manifold cover, and which exits via a grommet in the rear starboard corner of the lower engine cover, to show that the pump is pumping.
Fastbullet says there is no pressure control but ITYWF that the thermostat also acts as the pressure control valve. . I guess he means no separate pressure control valve
You may find the manual on the Boatinfo website helpful