Mercury – Impeller for 3.4L Carbureted Two Stroke Outboards | Cooling System Component | Flexible Marine Polymer | 85647

Overview
If you’ve spent enough weekends on the water, you know there are certain parts you never take for granted. An engine can sound strong, feel powerful, and look clean—but none of that matters if it can’t stay cool. That’s why the Mercury Marine part number 85647 Impeller gives boaters such peace of mind. It’s one of those quiet, behind-the-scenes components that keeps your trips running smooth, steady, and worry-free, whether you’re cruising at idle or running toward the next fishing spot before sunrise.

Key Features

• Maintains consistent engine cooling by circulating water through cooling passages

• Constructed from a durable, flexible marine-grade polymer

• Designed for dependable flexibility across seasonal temperature changes

• Engineered with precise vane alignment for smooth, reliable water flow

• Direct replacement for Mercury and Mariner 3.4-liter carbureted Two Stroke outboards

Engine & Boat Compatibility

• Fits Mercury and Mariner 3.4-liter Two Stroke carbureted outboard engines

• Common across mid-range and larger horsepowers built on the 3.4L platform

• Ideal for center consoles, offshore fishing boats, pontoon boats, aluminum rigs, and classic runabouts

• Compatible with cooling systems that require Mercury Marine part number 85647

Performance & Practical Benefits
A good impeller doesn’t try to impress you—you simply feel its work every time the engine holds a steady temperature. With the 85647 installed, the water pump performs with a smooth, confident rhythm. The polymer blades flex just enough to keep a strong seal inside the housing, grabbing and moving water with each rotation. That creates a more predictable cooling pattern, which translates into an engine that runs calmer and never feels like it’s fighting heat.

You’ll sense the difference the moment you ease the throttle forward. The motor stays consistent, even after long idle periods or quick jumps to higher speeds. The installation itself is clean and straightforward thanks to Mercury’s precise engineering. The part seats securely, fits tightly, and feels solid—no second-guessing, no awkward adjustments.

Longevity is another advantage boaters appreciate. The marine-grade polymer resists stiffening, cracking, and deformation, even after seasons of warm water, debris, and vibration. That means you spend more time enjoying the water and less time worrying about the cooling system. It’s the kind of reliability that seasoned boaters gravitate toward because it simplifies maintenance and keeps the engine healthy.

Why Buy OEM
When it comes to the cooling system, choosing an original Mercury Marine part is simply the smart move. The 85647 Impeller is designed by the same engineers who designed your outboard, which means the material blend, blade flexibility, and fitment were created to match your engine exactly. Aftermarket versions might mimic the shape, but they rarely deliver the same long-term durability or consistent water flow. With OEM, you get reliability, proper alignment, straightforward installation, and real value over time. It’s the kind of part you buy once and trust without hesitation.

FAQ

Q1: Which Mercury engines does the Mercury 85647 Impeller fit?
It fits Mercury and Mariner 3.4-liter carbureted Two Stroke outboards that specify this exact impeller.

Q2: What makes this part different from aftermarket alternatives?
Its polymer composition, blade design, and perfect fitment are engineered specifically for Mercury outboards, offering steadier cooling and better durability.

Q3: How do I know if this is the correct replacement?
Check your owner’s manual or existing part number. If your engine lists part number 85647, this is the correct OEM match.

Q4: Can this impeller be used in saltwater and freshwater?
Yes, it performs reliably in both environments and resists degradation from typical marine conditions.

Q5: Is installation straightforward for most boat owners?
Yes. Anyone familiar with routine maintenance will find the OEM fit clean, tight, and easy to install.