Amel Super Maramu 2000
After 8 months, the impeller would have lost its blades.
I have spare water pump, I just swap them and keep going.
Dec 2014, the water pump started to leak, so I hire someone to teach me to rebuild it.
To clean started with small screw driver to remove the big build up, then sand paper (280), then finishing with (800).
October 2015: 10 months later. No problem.
To my surprise the 10 month old impeller still has all its blades and they came back in straight position (still usable - so I kept as a spare)
Pictures 6, 7, 8 and 9 are the spare water pump.
(Below) After 10 months, can see the build up. The impeller still has all its blades.
Since they come back in straight position it is still usable and I keep as a spare.
(Below) Back up water pump before and after cleaning.