Mercury/Mariner 3.3–6 HP Impeller – High-Efficiency Small Engine Impeller

This Mercury/Mariner 3.3–6 HP impeller is ideal for small portable motors that often serve as the primary or auxiliary engine on tiny boats. It fits a wide range of models – from the older 2-stroke Mercury 3.3 HP to the popular 4-5-6 HP four-stroke engines co-produced with Tohatsu. The impeller features 6 flexible blades made of a special neoprene composite, delivering excellent pump performance. The even flow of cooling water through the motor prevents dangerous overheating, even when the engine runs at high RPM on a hot summer day.

Installing the new impeller is straightforward – it matches the original size and profile of the factory part (replaces OEM numbers 47-16154-3 / 47-16154-B for Mercury). This means it fits snugly on the pump’s keyed shaft and provides secure drive without slipping. It’s recommended to replace this impeller as a preventive measure at least once per season or every ~50–100 engine hours, since small engines often operate at high speeds which put stress on the impeller. A new impeller restores the full volume of water flow and ensures optimal cooling.

Mercury/Mariner engines from 3.3 to 6 HP are widely used for small inflatables (2–3 m), folding fishing boats, motorized canoes, or as auxiliary kickers on larger vessels. In such cases, cooling reliability is critical – overheating a small engine can quickly lead to failure. That’s where this impeller proves its worth: it’s designed to perform effectively at both low and high RPM, giving you peace of mind on the water. Carrying a spare impeller is wise, especially if you frequently operate in shallow sandy or silty waters – abrasive particles can wear the blades faster, but with this affordable spare part you’ll always be prepared.

• Tohatsu Compatible: Since many Mercury 4–6 HP models are built by Tohatsu, this impeller also fits the equivalent Tohatsu/Nissan engines, ensuring the same cooling performance.
• Light and Portable: Small engines are often carried and stored after use – this impeller is designed to withstand frequent start/stop cycles and the periodic stowing of the motor.
• For Fishing & Camping: Delivers reliable engine operation during extended fishing trips or camping voyages where the motor is a lifeline.
• Quick Emergency Fix: If you notice a reduced or lost water tell-tale (a sign of a bad impeller), having this spare impeller allows a boater to quickly restore cooling and continue the journey.
• Safety and Confidence: With a well-functioning impeller, your small outboard runs smoothly and reliably – essential for your safety when far from shore.