Water Pump Repair Kit – Fits Mercury & Mariner Outboards 30-70 HP (Replaces 77177A3)

Water Pump Repair Kit – Fits Mercury & Mariner Outboards 30-70 HP (Replaces 77177A3)

This comprehensive water pump repair kit is designed for Mercury and Mariner 2-cycle outboards from 30 HP through 70 HP, manufactured between 1977 and 1997. It provides all necessary components for a complete and reliable water pump service.

This kit is a direct replacement for multiple OEM and aftermarket part numbers, ensuring broad compatibility for the specified engine models.

• Includes key components such as the impeller, housing, face plate, and all required gaskets and seals.
• Engineered to meet or exceed original equipment specifications for performance and longevity.
• Installation requires the removal of the lower unit.

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 Water Pump Impeller (89983T)
• 1 x Upper Housing
• 1 x Lower Housing
• 1 x Face Plate
• 1 x Face Seal
• 1 x Seal Carrier
• 1 x Water Tube Coupling
• 1 x Drive Key
• Multiple gaskets (quantity varies by manufacturer)

Installation Guide

1. Disconnect Power: Disconnect the battery cables to prevent accidental starting.
2. Position the Engine: Tilt the engine up and secure it. Place a drain pan under the lower unit.
3. Drain Gear Lube: Remove the upper and lower drain screws from the gearcase and allow the lubricant to drain completely.
4. Remove the Lower Unit: Remove the bolts securing the lower unit to the engine. Carefully lower it from the drive shaft housing.
5. Access the Water Pump: The water pump is located on top of the lower unit. Remove the bolts to disassemble the housing.
6. Replace Components: Carefully note the order of all parts. Remove the old impeller, gaskets, seals, and wear plate, and replace them with the new parts from the kit. Lightly grease the new impeller.
7. Reassemble Pump: Reinstall the housing components, ensuring the impeller vanes are oriented correctly (typically by twisting the driveshaft in a clockwise direction). Torque bolts to specification.
8. Reinstall Lower Unit: Guide the lower unit back into place, aligning the driveshaft, shift shaft, and water tube. Secure with bolts.
9. Refill Gear Lube: Fill the gearcase with fresh lubricant from the bottom drain hole until it seeps out the top hole. Reinstall and tighten both screws.
10. Test Operation: Reconnect the battery. Start the engine using a water supply (flushing muffs) and check for a strong, steady stream from the tell-tale outlet.

Troubleshooting & FAQ

Q: How do I confirm this kit fits my specific engine model?

A: The most reliable method is to match your engine's serial number to the ranges listed in our "Compatible Engine Models" table. For Mercury/Mariner owners, use the linked serial number guide to find your number and confirm it falls within the specified range (e.g., "USA 0C159200-0G589999"). Cross-referencing the OEM part number (77177A3) is also a highly effective verification method.

Q: What are the common signs of a failing water pump?

A: The most common indicators include the engine overheating at idle or low speeds, and a weak or non-existent water stream from the "tell-tale" outlet port. A brittle or cracked impeller can no longer pump water effectively, leading to poor engine cooling.

Q: How often should the water pump impeller be replaced?

A: For preventative maintenance, it is recommended to replace your water pump impeller and gaskets annually or every 100 hours of operation, whichever comes first. This is especially important for boats used in saltwater, as salt can accelerate the degradation of rubber components.

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.