3T5-87322 Water Pump Impeller Service Kit - Reliable Repair for 40/50

In this review of the 3T5-87322 Water Pump Impeller Service Kit, the bottom line is simple: it is a practical, cost-effective repair option for owners of Tohatsu, Nissan and compatible Mercury Marine 40HP and 50HP outboards who need to restore cooling performance quickly. The kit provides all core wear components encountered during a lower gearcase impeller service and gets an engine back in service without the expense of a full pump replacement. For a mechanic or a hands-on boater who values a good fit and straightforward installation, this kit answers the need.

Key Features

• Complete repair parts: The kit contains a rubber impeller, wear plate, seal gaskets and driveshaft key so the common failure points are addressed in one repair.
• Hardware included: Bolts with washers and insert cup are provided to replace corroded or lost fasteners during service, reducing the need to source additional parts.
• Multiple OEM fit numbers: Matches Tohatsu Nissan part numbers 3T5-87322-3 and 3C8-87322-3 variants, which helps confirm compatibility with several engine lines.
• Cross-fit with Mercury Marine: Also fits many Mercury Marine 40HP and 50HP lower gearcase models so it serves owners of different brands with the same repair need.
• Cost effective alternative: Buying the impeller kit is generally less expensive than replacing the entire water pump assembly, making it a sensible maintenance choice.

Who It's For

This kit is aimed at do-it-yourself boat owners, marine mechanics and maintenance yards working on Tohatsu or Nissan 40HP and 50HP 2- and 4-stroke outboards, and owners of Mercury Marine engines that share the same lower gearcase configuration. It is especially useful when a failing impeller or worn wear plate is the root cause of overheating or poor cooling flow.

Those who should look elsewhere include owners uncertain of their exact gasket profile or anyone who prefers factory-sealed pump units; the note about choosing the correct gasket means you must match the original gasket to ensure a leak-free installation.

Pros & Cons

Pros

• Parts list covers the typical wear items so a full impeller service can be completed in one visit.
• Customers report the kit restores engine cooling and fits as expected, reflecting solid fit and functionality.
• Hardware and insert cup included reduce extra trips for small fasteners, saving time.

Cons

• Installation requires choosing the correct gasket matching the original, which may confuse some buyers and lead to returns if the wrong gasket is selected.

Specifications

Product type	Impeller repair kit
Compatible engines	Tohatsu Nissan 40HP and 50HP 2/4-stroke
Also fits	Mercury Marine 40HP and 50HP lower gearcase
Included parts	Rubber impeller, wear plate, seal gaskets, driveshaft key
Additional hardware	Bolts with washers and insert cup
Common part numbers	3T5-87322-3, 3C8-87322-3 and variants

Our Verdict

The 3T5-87322 Impeller Service Kit is a practical, value-minded choice for owners who need to repair cooling on 40HP and 50HP Tohatsu, Nissan and compatible Mercury outboards. It supplies the necessary wear parts and hardware for a typical lower gearcase impeller job, fits as expected according to users, and avoids the higher cost of a full pump assembly replacement. Buy this if you can identify the correct gasket and intend to perform a focused impeller service.

Frequently Asked Questions

Will this kit fit my Mercury 50HP engine?
It fits many Mercury Marine 40HP and 50HP lower gearcase models that share the same configuration; verify part compatibility before ordering.

What comes in the package?
The package contains a rubber impeller, wear plate, seal gaskets, driveshaft key, bolts with washers and an insert cup.

Do I need extra parts to install?
Mostly no, but you must choose the gasket that matches your original gasket to ensure a proper seal during installation.