Re: 1967 Model#3706 c 3 hp evinrude
Drain the lower unit of its gearlube.
Remove the four bolts that retain the lower unit and drop it away from the engine.
The water pump is atop the lower unit, I assume you'll see it. Remove the pump retaining screws. If the screws are very tight, use a hand held propane torch to heat and help loosen the screws.
Clean all surfaces as needed (impeller housing, plate, lower unit surface).
Hold housing in your left hand and spin the impeller into it in a counter clockwise motion. Insert driveshaft thru the impeller and housing and make sure that the key is secured into the impeller.
Apply a little sealer to the lower unit surface and lay the impeller plate upon it.
Have the lower unit gently secured in a vice or some such item, tilted forward somewhat, then use a long screwdriver of a tool of your choosing to stick down into the lower unit so as to align the pinion gear to accept the driveshaft.
Apply some sealer to the bottom sealing surface of the impeller housing, then (making sure that the key is still secured within the impeller), slide the driveshaft and water pump/impeller assembly into the lower unit and down into the pinion gear. Aligning the pinion gear with the driveshaft may require some patience and jiggling of the propshaft, driveshaft, whatever.
Tighten the water pump screws, check to make sure that there is impeller tension when you turn the driveshaft (key in impeller?), then fill the lower unit with gearlube to its oil level screw.
When inserting the unit back to the engine, make sure that the copper water tube slides within the impeller housing grommet. That's it.
