Quick Verdict
If your boat has no engine and you need a complete way to get on the water, the 3.5HP-7HP outboard motor is the whole package. If you already have a Caterpillar CAT 3412 or C32 marine engine, the water pump impeller is the maintenance part that keeps its cooling system working. The outboard lists at USD 187.75, the impeller at USD 83.24, a gap of about USD 104.51.
At a Glance
| Product | Listed Price | What It Does | Best For | Price Bar |
|---|---|---|---|---|
| 3.5HP-7HP Outboard Motor | USD 187.75 | Complete two-stroke outboard with water cooling | Small boats that need a new motor | |
| Caterpillar CAT 3412/C32 Impeller | USD 83.24 | Spline-drive impeller for CAT cooling pumps | Replacing an impeller in an existing CAT engine |
Where Each Product Wins
- Choose the outboard motor when you're buying a self-contained source of propulsion. The 3.5HP configuration produces a maximum 2.5kW output, has a 4000-5000 r/min full-throttle range, and uses a 6.7-inch three-blade propeller to move the boat.
- Choose the impeller when you're servicing an engine, not replacing one. It fits CAT 3412/C32 cooling pumps and uses a brass insert, which makes it a direct replacement rather than a universal part.
Product Notes
3.5HP-7HP Outboard Boat Motor
The title lists several horsepower options, but the specs describe the 3.5HP version specifically: a two-stroke engine with 2.5kW maximum output, a 4000-5000 r/min operating range, and a 27/13 gear ratio. The description highlights a streamlined 6.7-inch three-blade propeller intended to reduce water resistance, which is a useful feature for moving through varied water conditions. This is the purchase to make when you don't have an existing motor and want a complete outboard package rather than a component. One limitation to keep in mind is that the labeled 4, 6, or 7HP variants may have different performance numbers from the ones listed, so the 3.5HP specs shouldn't be assumed to apply to every version.
Caterpillar CAT 3412/C32 Water Pump Impeller
This replacement impeller is designed for the cooling pump on Caterpillar CAT 3412 and C32 marine engines. It lines up with OEM part numbers 1539123 and 1566892, and the fitment information covers CAT pump models 147-7850 and 212-7264. The spline drive and brass insert give it the specific mechanical fit that a generic replacement lacks. This is the right choice when your existing engine is healthy but its cooling pump needs a new impeller to circulate water properly. The limitation is that it's only one component: if you need a motor that produces thrust on its own, this kit won't do that. It exists to protect the engine you already have, not to replace it.
Final Choice by Use Case
For a boat sitting without power, the complete outboard motor is the option that gets you moving immediately, because it bundles the engine, cooling, and propeller into one purchase. For a boat with a Caterpillar CAT 3412 or C32 engine in place, the impeller is the practical buy that restores the cooling system's critical function. Let your current setup decide: no engine means choose the outboard; an engine with a tired impeller means choose the replacement part.
