Mercury - Heavy Duty Sea Water Pump Impeller Repair Kit MerCruiser 4.5L & 6.2L Composite & Elastomer 8M0137221. Overview. When you spend enough days on the water, you learn to appreciate parts that simply do their job without a fuss. That steady reliability becomes part of the boating experience-one less thing to worry about when you're watching the horizon or drifting into your favorite cove. The Mercury 8M0137221 Heavy Duty Sea Water Pump Impeller Repair Kit is one of those behind-the-scenes c