Not sure if the R25 is the same as our R27 but if it is I've attached Mike Rizzo's detailed instructions, hopefully this will help. If the R25 is different I'll bet someone else will let us know.
Good luck,
R-27 Impeller change
by knotflying on Wed Feb 06, 2013 12:28 pm
I just changed my impeller on my R-27. It took me 1.5 hours with the help of another person. Below are the steps I took:
Tools
22 mm socket 3/8 drive
6 mm hex male 3/8 drive
3” extension
3/8 drive ratchet
Long needle nose plier
¼ inch drift pin or Phillips screwdriver of same diameter
Paper towel
• Shut seacock valve
• Turn off engine switch
• Disconnect engine positive wire
• Remove interior panel that has 110 and 12 V outlet. This makes sliding and removing slide panel easier and allows for better vision from side into engine
• Remove Impeller pulley belt – From cockpit side have one person push on belt at bottom of impeller pulley. Have 2nd person in cockpit on port. Reach into crankshaft pulley with 22mm socket, extension and ratchet. Turn engine clockwise (as if you were looking aft) and belt will work off.
• The following work is from cockpit side. Having 2nd person looking from inside helps a bit
• Turn impeller pulley so that pulley slots allow access to hex bolts
• Put a piece of paper towel on male end of extension and force hex socket onto extension. This will prevent the socket from falling off.
• Feel your way to the hex bolt and insert drive into bolt and then attach ratchet. Just loosen bolt, do not remove.
• Do this same procedure for the three remaining bolts.
• Now put a piece of paper towel on the end of the hex drive and force that into the hex bolt. If you loosened your bolts enough you can screw them out with just the extension and no ratchet.
• Once all the bolts are out you can slide the pulley and housing out and the person inside can handle it through the step access.
• Get a good set of straight needle nose pliers and insert them with one end in shaft hole and one end between blades and yank. Once you have it out half way you can turn clockwise while pulling out and you should have it in hand.
• There is a small O-ring type washer on the motor side housing. Mine looked good so I did not replace it.
• Insert new impeller by working it in turning it clockwise and inward pressure. Once started push it in.
• Now insert pulley and shaft assembly. Line up holes using the drift pin in one of the holes.
• Do the paper towel trick, using only the extension and screw in like you would a screwdriver and be careful not to cross thread the bolts. First turn counterclockwise then clockwise so as to be sure you are not cross threading and hand tighten. Do this for the remaining bolts.
• Now remove the paper towel piece in between the 6mm drive and the bolt and now tighten all the bolts using the ratchet.
• Now with the help of the 2nd person. Place the belt around the drive pulley and start it on the impeller pulley at the bottom
• Go back to your removal positions and turn the engine clockwise while the impeller person works the belt on.
• Visually inspect from the inside to be sure belt is on both pulleys appropriately.
• Reconnect engine power cable, turn on engine battery switch and open the seacock.
• Check for any leaks.
• Start engine, check that water is discharging, and look for leaks.
• Hi five and have a beer.
