Reply With QuoteChange the impellar every year whether there's been no use or lots of hours. Cheap protection for you wallet. Impellars die due to lack of lubrication (water), and they'll die due to time. Rubber doesn't last forever. Rarely will you find an actual obstruction at the vanes that'll peel the impellar. I would suggest having a drain on the motor (petcock) or a dump easily seen so you can check water flow as part of luanching. NO WATERFLOW - NO GO! Most boats are able to pick up water on plane , enough to cool the motor under usual loads, but if you loose a vane or two - and they easily get stuck in the plumbing, you'll over heat in a few short minutes. Worst part, it will not only take your motor but uncooled exhaust will burn/scorch every rubber item nearby. If it does burn through your rubber exhaust hose that's below the water line, there willl be water pouring in even if your on plane, let alone sitting on a beach waiting for the trailer.
