Re: 25hp 2 stroke mercury water pump change
No expert but I've done my own. I don't have a diagram but I can give you some steps.
1. Put in forward, Remove the air resonator off the carb....8mm deep well socket, 2 bolts. Remove the starter, 2 bolts...10mm I believe. Disconnect the wire underneath the starter and remove it.
2. Coming through the bottem of the coweling is the shift rod, right beneath the carb. On the side of the cam holding the rod is a bolt, remove it..10mm. Slide the bolt side if the cam off with a flathead screwdriver...DON'T FORCE IT OR DAMAGE IT. Be gentle with it.
3. Slide the shift rod off the little steel pin that runs through the cam.
4. On the lower unit is 2 bolts on each side, and one on the top of the lower holding the annode in place. Remove them while you hold pressure on the lower unit. After this there is nothing else holding it in place.
5. Slide the Lower unit down. May have to tap it with a rubber hammer to break it lose. Remove the water pump cup (around the driveshaft) and replace the impellar. Add a little grease to new impellar and inside the cup to reduce friction when re-installing. Inspect all O-rings and gaskets in the water pump assembly for possible replacement. Re-install the new pump (make sure you re-install the waterpump key also).
6. Carefully raise the lower unit back in postion. Make sure the water inlet tube follows the canal by the exhaust tube so it will guide it's self back into the grommet. May have to spin the prop to make the drive shaft teeth align with the teeth in the powerhead while you steadily apply pressure. When it mates with the midsection, replace the mounting bolts. NO LOKTITE. re-intall the shift shaft to the cam and replace the re-intall the other parts.
Start her up and check the water pressure. It's actually a pretty simple job and good luck.
