Water Pump Impeller Kit with Housing – Fits Mercury/Mariner 30-70 HP (Replaces 46-77177A3, 77177A3)

Water Pump Impeller Kit with Housing – Fits Mercury/Mariner 30-70 HP (Replaces 46-77177A3, 77177A3)

This water pump impeller kit with housing is designed for Mercury/Mariner 30-70 HP 2-stroke outboard engines manufactured between 1977 and 1997. It provides a reliable solution for maintaining your engine's cooling system for optimal performance and longevity.

This kit is a direct replacement for Mercury OEM parts 46-77177A3 / 77177A3 and aftermarket parts including Sierra 18-3324, GLM 12100, and Tutorautomotive 46-01115.

• Includes all necessary components for a complete water pump overhaul, including the impeller, housing, base, plates, gaskets, and o-rings.
• Engineered as a direct OEM replacement to ensure a straightforward, hassle-free installation.
• The impeller is constructed from a high-quality, durable neoprene rubber compound for enhanced service life.

Part Number Cross-Reference

Use this table to confirm equivalent part numbers across OEM and aftermarket brands.

Compatible Engine Models

Confirm your engine model/year in the table below. For Mercury owners, here’s a guide to help you identify your engine’s serial/model: Mercury Serial Number Guide. You can also review exploded diagrams to verify part numbers: Mercury Parts Diagrams & Catalog.

Technical Specifications

Package Contents

This comprehensive kit includes the following components:

• 1 x Water Pump Impeller (47-89983/18-3007)
• 1 x Upper Pump Housing (46-77822A1/18-3118)
• 1 x Water Pump Base (46-77177A1)
• 2 x Plate (27-32770/27-19551)
• 2 x Drain Gasket (12-20260/12-19183)
• 1 x Drain Plug (12-49221)
• 3 x Water Pump Base Gasket (27-32771/27-77417/27-19552)
• 3 x O-Ring (25-26855/25-45711/25-26722)

Explosion Diagram

Installation Guide

1. Safety First: Disconnect the battery cables and disable the ignition system before beginning work.
2. Access the Lower Unit: Remove the bolts securing the gearcase (lower unit) to the engine's midsection.
3. Detach Gearcase: Carefully lower and remove the gearcase assembly. You may need to disconnect a speedometer tube or shift linkage.
4. Remove Old Pump: Unscrew the bolts on top of the water pump housing and lift it off to expose the impeller.
5. Inspect and Clean: Remove the old impeller, key, and gaskets. Thoroughly clean all mating surfaces, removing any old gasket material or debris.
6. Install New Impeller: Place the new gaskets and wear plate. Slide the new impeller key onto the driveshaft flat spot and push the new impeller down while turning the driveshaft clockwise to seat the vanes correctly.
7. Reassemble Pump: Install the new housing, gaskets, and O-rings from the kit. Tighten the housing bolts to the manufacturer's specified torque.
8. Reattach Lower Unit: Guide the gearcase back into position, ensuring the driveshaft, water tube, and shift shaft align properly.
9. Final Checks: Reinstall and tighten the gearcase bolts. Reconnect the battery.
10. Test Operation: Start the engine in water using a flush attachment or in a body of water. Confirm a steady stream of water is exiting the "tell-tale" port.

Troubleshooting & FAQ

Q: How do I confirm this kit fits my specific engine?
A: Check the compatibility table on this page, which lists Mercury/Mariner models by HP, cylinder count, and year range. Critically, you should match your engine's serial number to the ranges provided in the "Notes" column for a guaranteed fit.

Q: What are the signs of a failing water pump impeller?
A: Common signs include the engine overheating at idle or low speeds, a weak or inconsistent stream of water from the tell-tale outlet, and visible cracks or stiffness in the old impeller's rubber vanes upon inspection.

Q: How often should I replace my water pump impeller?
A: For preventative maintenance, it is recommended to inspect the impeller annually and replace it every 1-2 years or every 100-200 hours of use, depending on operating conditions (e.g., saltwater vs. freshwater).

Q: OEM vs. Aftermarket?
A: This listing is an aftermarket replacement part (not an OEM component). We build to OEM specifications using comparable-grade materials. Production is done in an ISO9002-certified facility, and each batch is inspected for consistent performance.

Q: How fast do you ship and how much does it cost?
A: We offer fast global shipping—typically 5–15 days worldwide—and standard shipping is free. Expedited options are available at checkout depending on your location.

Q: What is your warranty and return policy?
A: This product includes a 1-year warranty against manufacturing defects under normal use. If something goes wrong, contact our support team with your order details. Returns are accepted within our standard return window (unused & in original condition); please see our policy page or reach out for instructions.

Important Notes

• Verify that the product images and specifications match your original part. If discrepancies exist—even if your model is listed—do not proceed with the purchase.
• This product is an aftermarket replacement part and is not an OEM component.
• Professional installation is recommended to ensure safety and optimal performance.

Why Choose JLM MARINE?

• Quality Assured: As a trusted manufacturer for over 20 years, we supply top marine brands globally.
• Fast Global Shipping: Free delivery worldwide in 5–15 days.
• Direct from Manufacturer: Competitive pricing without compromising quality.