Mercury - Water Pump Impeller Cooling System Elastomer Construction 952892. Overview. On a small outboard, every sound and vibration feels personal. You hear the rhythm of the engine, feel the push of the prop, and count on that little powerhead to move you across the water without complaint. That's why a healthy cooling system matters so much. The Mercury 952892 Water Pump Impeller brings back the confidence you expect from a well-tuned 3.3hp Mercury or Mariner outboard. It restores that steady