Sierra 18-8911 Impeller-Yamaha 2.5-3Hp 1988 & Up

Why Your Yamaha Outboard Needs a Reliable Impeller Like the Sierra 18-8911

Keeping your Yamaha 2.5-3HP outboard motor running cool and strong starts with the heart of its water pump: the impeller. Over time, these rubber components wear down from constant exposure to water, sand, and debris, leading to overheating that can spell disaster on the water. The Sierra 18-8911 steps in as a trusted replacement, designed specifically for Yamaha engines from 1988 and newer. Boat owners swear by it for restoring peak cooling performance without the hassle of sourcing originals.

Unlike stock parts that might flake or lose flexibility after a season, this impeller holds up under real-world abuse. It's crafted from high-quality neoprene elastomer, offering superior resistance to heat, oil, and chemicals—common culprits in marine environments. Whether you're trailering to the lake or pushing through choppy bays, it delivers consistent water flow to prevent engine damage.

Perfect Fit for Your Yamaha 2.5-3HP Models

Engineered as a direct OEM-style replacement, the Sierra 18-8911 slots right into Yamaha 2.5HP and 3HP two-stroke outboards produced from 1988 onward. Think models like the 2.5A, 2.5B, 3A, and their variants—check your service manual for exact matches, but it's a go-to for most setups in that range. No modifications needed; it uses the factory mounting hardware and seals for a leak-free install.

Pro tip: Pair it with a fresh pump housing gasket during replacement to maximize longevity. Many mechanics recommend inspecting the entire water pump assembly while you're in there, as wear on one part often signals issues elsewhere.

Effortless Installation and Maintenance Insights

Swapping out an impeller doesn't have to be a weekend project. With basic tools—a flathead screwdriver, pliers, and some soapy water for lubrication—you can do it in under an hour. Start by disconnecting the fuel line and tilting the motor for access. Gently twist the old impeller out counterclockwise, clean the housing thoroughly, then lube and insert the new one clockwise until it seats fully. Reassemble, prime the pump by running in a barrel of water, and you're back on the water.

• Prep tip: Warm the engine slightly to soften the old impeller for easier removal.
• Lube choice: Use marine-specific lubricant or a 50/50 glycerin-water mix—avoid petroleum-based products that degrade rubber.
• Seasonal check: Inspect annually or every 100 hours; replace if vanes are chipped, swollen, or glazed.

Regular maintenance like this not only extends engine life but also boosts resale value. Skip it, and you risk vapor lock or seized pistons from poor cooling.

Real Benefits Backed by Boaters

Choosing Sierra means reliability without compromise. This impeller spins up full water pressure quickly, even in low-RPM scenarios, ensuring your Yamaha idles cool during trolling or docking. It's a favorite among weekend warriors and charter captains alike for its balance of durability and affordability. No more guessing if your cooling system's up to snuff—install one and feel the difference in smooth, worry-free runs.