Tutor Auto Water Pump Repair Kit 77177A3 for Mercury & Mariner 30–70 HP — Housing, Neoprene Impeller & Seal Kit

The Tutor Auto 77177A3 Water Pump Repair Kit is a complete replacement kit with housing designed to restore cooling performance on Mercury and Mariner 2-cycle outboards from 30 HP to 70 HP.

If your two-stroke outboard is running hotter than usual or you notice reduced water flow from the telltale, a worn impeller or leaking pump housing is often the cause. This kit supplies the commonly replaced components—neoprene impeller, gaskets, seals, and housing—to rebuild the seawater pump and return the lower unit to factory-style operation. It replaces Mercury part numbers 77177A3 and 46-77177A3, and aftermarket equivalents like Sierra 18-3324 and GLM 12100.

How will this kit help my outboard’s cooling system?

Replacing the impeller and associated seals restores the pump’s ability to move cooling water through the engine, preventing overheating and maintaining consistent operating temperatures. The included housing and gasket ensure a snug, leak-free assembly that matches OEM fitment.

• Neoprene rubber impeller for flexibility and wear resistance
• Complete set of gaskets and seals to prevent leaks
• Housing replacement for worn or cracked pump bodies
• Direct-fit design for quick installation without modification

Which engines and years does this replacement kit fit?

This kit is intended for Mercury and Mariner 2-cycle outboards rated from 30 HP up to 70 HP and covers models produced roughly between the late 1970s and 1997. It’s a direct replacement where factory part numbers 77177A3, 46-77177A3, Sierra 18-3324, or GLM 12100 are specified.

• Compatible with 30, 35, 40, 45, 50, 60, 65 and 70 HP 2-stroke outboards
• Fits many models manufactured c.1977–1997—check your parts list
• Designed to conform to original pump geometry for correct flow

What’s included and why is it better than replacing only the impeller?

Rather than swapping just the impeller, this repair kit bundles the critical wear parts so the entire wet side of the pump is renewed. A fresh housing and complete gasket/seal set eliminate common failure points that a lone impeller replacement can’t fix.

• Pre-assembled kit saves time sourcing individual parts
• Materials meet or exceed OEM specifications for durability
• Eliminates hidden leaks or damaged housing issues during reassembly

How do I install this kit and what tools are typically needed?

Installation requires basic marine mechanic tools and moderate mechanical skill: remove the lower unit, disassemble the pump, swap the impeller and housing, and torque fasteners to spec. If you’re comfortable with routine lower-unit service, this is a straightforward job; otherwise a marine shop can fit it quickly.

• Common tools: socket set, screwdrivers, seal puller, torque wrench
• Follow engine manual for lower-unit removal and torque values
• Inspect driveshaft and water passages while the unit is open

Who is this for: Boaters, DIY mechanics, and marine technicians who operate or service Mercury/Mariner 2-stroke outboards between 30 and 70 HP and want a cost-effective, OEM-fit pump rebuild. This kit suits owners performing scheduled maintenance, preparing a boat for season, or repairing a pump after impeller failure. Tutor Auto backs the product with a lifetime warranty and offers replacement or refund if parts are unsatisfactory, making it a practical choice for reliable cooling system restoration.