This post describes how to replace the water pump.
All parts were purchased from my friend Andy at Shipyard Island Marine Engine Parts.
The parts that were used are all included in the Yamaha Water Pump Kit.
Andy, thanks for the great moral support and great price on these parts!!
Thanks to TrollnHeel for taking the pictures, getting me beers, and helping GET-R-DONE.
Thanks to THE BOAT MONKEY for his supervision and comic relief.
Be sure the engine is in neutral.
Remove the lower unit cowling. There are 6 hex bolts total. You do not have to perform this step, but I did not want to damage the cowling.
Be sure to keep up with the "tab nuts" that may fall out of the slots in the cowling. They are located in the 2 bottom holes on the front side of the cowling.
Remove the rubber plug to access the trim tab bolt.
Tilt the motor up and remove the prop.
Make note of the location of the tab.
Remove the trim tab bolt.
Remove the other two bolts from under the lower unit.
Remove the other 6 bolts from the lower unit, 3 on each side.
Carefully work the unit up and down while pulling outward; the lower unit should come free. There is no speedometer tube that you have to disconnect.
My Black and Decker Workhorse provided a stable platform to perform the work.
Remove the 4 water pump housing bolts.
Remove the housing.
Remove the o-rings.
Remove the SS driveshaft cover. I used a large screwdriver and worked around the cover.
Slide the plastic compression ring off.
Remove the SS impeller housing.
Remove the three SS washers. I kept them in the same order for re-install.
Remove the impeller.
Remove the woodruff key. I used an awl, worked perfectly.
Remove the SS bottom plate.
Remove the gasket.
Clean off any gasket material you see.
Blow the area clean.
Remove the old dowel pins.
Install the new dowel pins.
Install the new gasket.
Install the new bottom plate.
Install new woodruff key.
Install the new impeller. The side with the dots is up and the side with the slashes is down. Slide it down the shaft and align the slot in the impeller with the key. You should be able to push it all the way down with your hands, although it may take a little effort.
Clean and re-install the SS washers.
Install the new impeller housing. It will help to put some grease around the walls of the housing. Use one hand to bend the fins of the impeller while you carefully push down with the other hand. Remember, the shaft turns clockwise, so the fins need to be bent accordingly. The center of the opening at the bottom of the housing should be pointing to about 4 o'clock if you look at it from the prop-end of the lower unit.
Clean and re-install the plastic compression ring.
Clean and re-install the SS driveshaft cover. I used an adjustable wrench for this. I opened up the jaws of the wrench until it would clear the driveshaft, then let it rest on the SS cover and used a hammer to gently bump it down.
Clean the water pump housing. I applied some grease to the slots for the o-rings to help hold them in place.
Re-install the water pump housing. Be sure the o-rings stay in place. As you slide the housing down, rotate the driveshaft to align the impeller housing with the pump housing until it slides all the way down over the dowel pins.
Apply some anti-seize compound to the threads of the new bolts and install them.
Be sure to apply some grease to the fittings for the water pump inlet and the speedometer tube. Apply grease to the driveshaft splines and shifter splines.
While you have the lower unit off, now is a good time to blow out the speedometer tube. Mine had stopped working several months ago. TrollnHeel unplugged the tube from the back of the speedometer and used the compressor to blow out the trash.
Re-install the lower unit in the reverse order. Before you put all the bolts back in, make sure the prop shaft turns freely to ensure that the shift rod did not move while you were sliding the unit back on. If it does not spin freely, or if you hear a "clicking" sound, the shift rod is out of alignment and you will need to remove the lower unit, adjust the rod, and re-install the lower unit. When the shift rod is in the NEUTRAL position, the prop should spin FREELY. Be sure to apply some anti-seize compound to every bolt.
Before re-installing the prop, remove the thrust washer and inspect it for wear, re-install it and grease the prop shaft splines.
I hope this article helps someone.