16159A1 Water Pump Impeller Repair Kit for Mercury 4 5 6 HP - Reliable

In this review the 16159A1 Water Pump Impeller Repair Kit is judged on fit, completeness and ease of installation for small outboard engines. It is aimed at owners of Mercury 4HP, 5HP and 6HP motors and compatible Nissan Tohatsu MFS models who need a full rebuild of the lower unit water pump. The single biggest reason to buy is the complete set of replacement parts included in one package, allowing a thorough rebuild without separate parts hunting and getting the engine operational again.

Key Features

• Complete rebuild set: The kit contains an impeller, driveshaft pin, cup liner, wear plate, gaskets, bolts and washers so a full water pump service can be done in one job.
• Wide compatibility: It fits Mercury 4HP 5HP 6HP models and Nissan Tohatsu MFS 4 5 6 HP pumps, making it useful for multiple small outboards.
• OEM cross reference: The kit covers Mercury part numbers such as 16159A03 and 16159A1 and Tohatsu part numbers like 369873221M, helping ensure correct fit when replacing worn components.
• Restores cooling reliability: Replacing the impeller and wear components refreshes water flow and reduces the risk of overheating during operation.
• Value for money: Customers report the parts match original dimensions and return engines to service without needing extra purchases.

Who It's For

This kit is for boat owners, DIY mechanics and small repair shops that maintain Mercury 4, 5 and 6 HP outboards or Nissan Tohatsu MFS 4-6 HP engines and prefer to perform a full water pump rebuild themselves. It suits anyone who wants the convenience of a matched set of parts so they can replace the impeller, liner, wear plate and fasteners in one service interval.

It is not for larger outboard owners or for engines outside the listed horsepower and part number range; those users should verify compatibility or seek a kit specific to their model. Professional technicians working on a wider range of models may also prefer OEM individual parts when exact factory sourcing is required.

Pros & Cons

Pros

• Complete collection of parts included so the water pump rebuild requires no extra components.
• Good fit to the listed Mercury and Tohatsu part numbers, matching original dimensions for a dependable repair.
• Customers report restored engine cooling and immediate return to service after installation.

Cons

• Compatibility is limited to specific Mercury and Tohatsu 4-6 HP models, so users must check part numbers before purchase.

Specifications

Product type	Water pump impeller repair kit
Compatible brands	Mercury, Nissan Tohatsu
Horsepower fit	4 HP, 5 HP, 6 HP
Included parts	Impeller, driveshaft pin, cup liner, wear plate, gaskets, bolts, washers
Mercury part numbers	16159A03, 16159T01, 16159A1, 8M0155395
Tohatsu part numbers	369873220, 369873221M, 369-87322-1, 369873222

Our Verdict

The 16159A1 water pump impeller repair kit is a practical, cost-effective solution for owners of Mercury and Nissan Tohatsu 4-6 HP outboards who need a complete pump rebuild. It delivers the essential parts in one package, fits the referenced part numbers, and restores cooling performance without extra sourcing, making it a sensible buy for DIY maintenance and routine service intervals.

Frequently Asked Questions

Will this kit fit a Mercury 5 HP outboard?
Yes, it is specified to fit Mercury 4HP, 5HP and 6HP motor models when the part numbers match.

Does the package include gaskets and hardware?
Yes, the kit contains gaskets, bolts and washers in addition to the impeller, driveshaft pin, cup liner and wear plate.

Is this compatible with Tohatsu MFS engines?
It fits Tohatsu MFS 4, 5 and 6 HP water pumps that use the listed 36987322x part numbers.