A: Yes, you should take it to be repaired. I wouldn't settle for the local marina, however, unless it offers authorized Mercury service. Outboard manufacturers often make changes or discover service information that's model specific. They publish these as Service Bulletins. There may very well be one or more of these that pertain to your engine's cooling system. It doesn't sound to me as if you installed a complete water pump kit. You mention replacing the impeller and the impeller housing, but you don't say anything about the pressed-in, stainless-steel cup in the impeller housing and the stainless-steel impeller plate that's underneath the impeller. Both of these parts wear and require periodic replacement. If you operate an engine in silt- or sand-laden water, you can render these parts useless in a matter of minutes. They can become scored or develop wear overall. If this is the first impeller you've installed in this engine, you've been very fortunate. Normally, you should install a new water pump kit every other year. A complete kit includes: impeller housing and cup, impeller plate, impeller, gasket, and new hardware (fasteners, drive key, and so on). For the owners of new outboards, many dealerships are suggesting water pump overhauls after every 100 hours of operation. And be sure to get the stainless-steel parts inspected and replaced if they show any wear. It's cheap insurance compared to a fried engine.