replacing/checking impellers
 

New engine & FWC (mm) 04/2014. replaced raw water impeller in 2016, looking back at it, it most likely didn't need it. so now I'm going to replace both since its been 3-5 years. My question is should I clamp off the hoses to keep from dumping a bunch of fluid into the bilge. I have less than 100 hours on the engine, it runs great and starts perfect. The boat is a 68 Columbia 36,
thanks for the help

If you can somehow position an empty container near the pump, and immediately direct the hose into it when you remove it from the pump, you may be able to keep the spillage to a minimum. At 100 hours, you probably have 100 hours to go before you really need to think about replacing the impellers. To quote the instructions for the Moyer pump:
Impeller: In normal service (50 to 100 hours per year), impeller changes are recommended every 3 to 4 years, depending on the quality of the raw water in your operating area. When used in an enclosed freshwater cooling system, impeller change intervals can be increased to every 4 or 5 years.

These hose clamps work pretty well. Harbor Freight.