Mercury/Mariner 4–10 HP Impeller – Heavy-Duty 6-Blade Cooling Rotor

The Mercury/Mariner 4–10 HP impeller is built for reliable performance in older series outboard motors, where proper cooling is crucial to the engine’s longevity. This model covers various horsepower ratings (4 HP, 4.5 HP, 7.5 HP, 9.8 HP, 10 HP) common to Mercury/Mariner engines of the 1970s, 1980s, and 1990s. With its six blades of highly durable neoprene, the impeller provides strong coolant flow, keeping engine temperatures within optimal limits. Even at high RPM or in warm weather, your classic engine will stay cool and protected.

Replacing the impeller is straightforward – its design mirrors the original (equivalent to Mercury OEM #47-65957 and #47-89981), ensuring a perfect fit. This is especially important for older engines, where precise parts compatibility is key to trouble-free operation. During replacement, it’s advisable to also check the condition of gaskets and the water pump housing to ensure the entire system is in good order. Regular maintenance that includes changing the impeller every 1–2 years is an inexpensive way to keep these vintage motors running.

Mercury/Mariner 7.5–10 HP engines were once popular on boats around 4–5 meters in length, and 4–5 HP engines were used on smaller dinghies and tenders. Many of these motors are still in service today by enthusiasts and classic boat owners. For them, this impeller is indispensable – it breathes new life into the cooling system. Whether you’re restoring a vintage motor or maintaining one in regular use, this spare impeller will ensure your engine doesn’t overheat. Having a backup impeller is a smart practice, especially when taking a classic motor on a long cruise or to a show – it can be the difference between a successful outing and a breakdown.

• Saving the Classics: Meant for retro Mercury/Mariner motors where OEM parts might be scarce – this impeller provides the same effectiveness as the original.
• High RPM, No Worries: Reinforced construction allows the impeller to perform reliably even when the engine is at full throttle, maintaining optimal cooling.
• For Collectors & Hobbyists: Ideal for those who upkeep classic boats and engines – it gives confidence that the cooling system is up to par.
• Preventive Replacement: For older engines that may have sat unused, swapping the impeller before the season’s first run is highly recommended.
• Handles Harsh Conditions: Whether in shallow rivers or salty bays, the impeller’s material withstands sand, silt, and salt, retaining its flexibility.