Sierra 18-3017 Mercury/Mariner Impeller Repair Kit

Revitalize Your Outboard's Cooling System with Reliable Impeller Repair

Keeping your Mercury or Mariner outboard motor running cool and efficient is crucial for those long days on the water. The impeller in your water pump takes a beating from sand, debris, and constant use, leading to overheating risks if it fails. This repair kit steps in as a cost-effective solution, providing all the essential components to restore proper water flow without a full pump overhaul.

Unlike temporary fixes, this kit delivers durable materials that match or exceed original equipment standards, ensuring your engine stays protected season after season. Boat owners rave about the straightforward rebuild process that gets them back on the water quickly.

Key Components and What They Do

• High-Quality Impeller: Precision-molded rubber with flexible vanes that grip and pump water efficiently, resisting wear from abrasive environments.
• Drive Key: Ensures positive engagement between the impeller and driveshaft, preventing slippage during high-RPM operation.
• O-Rings and Gaskets: Create a watertight seal to eliminate leaks and maintain optimal pressure.
• Hardware Essentials: Includes necessary screws and fittings for a complete, hassle-free assembly.

These parts work together to mimic factory performance, delivering the cooling capacity your engine demands in saltwater, freshwater, or muddy conditions.

Perfect Fit for Mercury and Mariner Models

Engineered specifically for a wide range of Mercury and Mariner outboards, this kit fits seamlessly into popular powerheads. Always cross-reference your engine's serial number with the full application guide to confirm compatibility—covering everything from 2-stroke to 4-stroke setups commonly found in 40HP to 125HP ranges.

Whether you're maintaining a classic workhorse or a modern recreational rig, this repair restores factory-spec water pump function, helping prevent costly engine damage from overheating.

Step-by-Step Installation Guide

Replacing a worn impeller doesn't require a marine mechanic's expertise. With basic tools like pliers, a screwdriver, and some soapy water for lubrication, most DIYers complete the job in under an hour.

1. Disconnect the fuel line and tilt the outboard for access to the lower unit.
2. Drain the gear lube and remove the water pump housing—note the orientation of the old impeller.
3. Clean the housing thoroughly to remove debris, then install the new drive key.
4. Lubricate and twist the impeller onto the driveshaft (install the key first for alignment).
5. Reassemble with fresh O-rings and gaskets, torque to spec, and test-run in a barrel of water.

Pro tip: Mark your calendar for annual inspections, especially if you frequent shallow or silty waters. Fresh gear lube during the process extends the life of related components.

Why This Kit Outshines Basic Replacements

Boat maintenance pros choose this for its superior rubber compound that stays pliable in extreme temperatures, from icy launches to scorching summers. It reduces cavitation risks and maintains consistent water pressure, directly impacting fuel efficiency and engine longevity.

Users report fewer breakdowns and smoother idling post-install, making it a smart upgrade for trailered boats, fishing charters, or family cruisers. Invest in reliability that handles real-world abuse.

Spotting Impeller Failure Early

Don't wait for steam rising from your cowling. Watch for these red flags:

• Telltale stream weakens or stops after warmup.
• Engine temperature climbs despite good airflow.
• Unusual noises from the lower unit during throttle-up.
• Visible chunks in the pee stream or gear lube.

Addressing these promptly with a fresh kit keeps adventures uninterrupted and repair bills low.