Water Pump Impeller Kit – Fits Mercury/Mariner 2-Cycle 30-70 HP (Replaces 46-77177A3, 77177A3)

Water Pump Impeller Kit – Fits Mercury/Mariner 2-Cycle 30-70 HP (Replaces 46-77177A3, 77177A3)Water Pump Impeller Kit Fits Mercury Mariner 2 Cycle 30 70 HP This water pump impeller repair kit provides a complete solution for servicing the lower unit water pump on a wide range of Mercury and Mariner 2 stroke outboard engines from 30 HP to 70 HP (19761997). It is designed to restore cooling system performance and prevent engine overheating. Directly replaces Mercury OEM part numbers 46 77177A3 and 77177A3, as well as aftermarket parts from

Water Pump Impeller Kit – Fits Mercury/Mariner 2-Cycle 30-70 HP

This water pump impeller repair kit provides a complete solution for servicing the lower unit water pump on a wide range of Mercury and Mariner 2-stroke outboard engines from 30 HP to 70 HP (1976–1997). It is designed to restore cooling system performance and prevent engine overheating.

Directly replaces Mercury OEM part numbers 46-77177A3 and 77177A3, as well as aftermarket parts from Sierra, GLM, Mallory, and others, ensuring broad compatibility.

• Engine Compatibility: Fits various Mercury/Mariner 2-stroke 30-70 HP models, including 30 JET, 35, 40, 45, 50, 60, 65, and 70 HP.
• Complete Kit: Includes all necessary components for a full rebuild: impeller, housing, base, plates, gaskets, and hardware.
• Installation Type: Engineered as a direct OEM-equivalent replacement for a precise fit.

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

• 1 x Impeller (47-20268)
• 1 x Impeller Plate (32768)
• 1 x Impeller Key
• 1 x Water Pump Housing (46-48746A1)
• 1 x Water Pump Base (46-77177A1)
• 1 x Water Pump Base Gasket (27-32771)
• 1 x Water Pump Base Gasket (27-77417)
• 1 x Lower Water Pump Gasket (27-32769)
• 1 x Upper Water Pump Gasket (27-19551)
• 2 x Drain Screw Gasket (12-19183)
• 1 x Rubber Washer (12-49221)
• 3 x O-Ring
• 1 x Exhaust Leg Rubber Seal (37721) - Note: This part is included in some kits but not all. Please verify if needed for your specific application.

Installation Guide

1. Safety First: Disconnect the battery and remove the spark plug wires. Secure the outboard in a suitable position.
2. Access the Lower Unit: Shift the outboard into neutral. Loosen and remove the bolts securing the lower unit (gearcase) to the upper leg.
3. Remove the Old Pump: Carefully drop the lower unit. The driveshaft will come with it. Unbolt and remove the old water pump housing to expose the impeller.
4. Inspect and Clean: Remove the old impeller, key, wear plate, and gaskets. Thoroughly clean all mating surfaces, removing any old gasket material or corrosion.
5. Install New Components: Place the new gaskets and wear plate onto the gearcase. Slide the new impeller key into the driveshaft keyway.
6. Install the Impeller: Lubricate the new impeller with a marine-safe grease or soapy water. Slide the impeller onto the driveshaft, turning the shaft clockwise to bed the vanes correctly.
7. Install the Housing: Apply lubricant inside the new housing. Press the housing down over the impeller, ensuring the vanes are correctly oriented, and align the bolt holes.
8. Secure and Reassemble: Secure the new housing with the provided bolts, tightening them to the manufacturer's specified torque.
9. Reinstall Lower Unit: Carefully guide the driveshaft back into the engine, ensuring the water tube and shift shaft align. Secure the lower unit with its bolts.
10. Final Checks: Reconnect the spark plug wires and battery. Test the engine using a water source (flushing muffs or in the water) and confirm a strong, steady stream from the cooling system's tell-tale outlet.

Troubleshooting & FAQ

Q: How do I confirm this fits my engine?
A: The most reliable method is to check your engine's model, horsepower, and serial number against our "Compatible Engine Models" table. For Mercury/Mariner models, the serial number is critical for identifying the correct year and model range, as there are often overlaps.

Q: What are the signs of a failing water pump impeller?
A: Common signs include an overheating engine alarm, a weak or non-existent water stream from the "tell-tale" outlet, or finding pieces of rubber in the cooling passages. A visual inspection may also reveal cracked, brittle, or missing impeller vanes.

Q: How often should the impeller be replaced?
A: As a general maintenance rule, it is recommended to inspect the impeller annually and replace it every 1-2 years or every 100-200 hours of use. Replacement frequency should be increased if operating in saltwater or sandy/silty conditions.

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.