Water Pump Impeller Kit – Fits Mercury/Mariner 65-220HP & MerCruiser Alpha One (Replaces 46-96148A8, 46-96148Q8, 46-96148T8)

Product Details

This complete Water Pump Impeller Kit provides everything needed for a full service of the lower unit water pump on a wide range of Mercury/Mariner outboards and MerCruiser sterndrives. It is designed for Mercury/Mariner 65–220HP 2-stroke models (4-cylinder through V6 with short-vane impellers) and MerCruiser Pre-Alpha (1970–1983), Alpha One (1983–1990), MC-1, R, and MR drives with serial numbers between 2491586 and 0D469858.

This kit is a direct interchange for Mercury part numbers 46-96148A8, 46-96148Q8, and 46-96148T8, as well as Sierra 18-3217 and Quicksilver 96148Q8. It also replaces Sierra 18-3316 when a complete housing is required.

• Engineered for direct-fit installation, matching OEM specifications.
• Features a durable plastic housing and a high-performance neoprene impeller.
• Includes the impeller, housing, wear plate, and all necessary gaskets and seals for a comprehensive rebuild.

Part Number Matrix

Use this matrix to confirm equivalent references across OEM and aftermarket.

Engine & Model Compatibility

Confirm your engine model and serial number in the tables below. Compatibility depends on the serial number range for many models.

Mercury/Mariner Outboards: Designed for 2-stroke, 4-cylinder through V6 models equipped with short-vane impellers.

MerCruiser Sterndrives: Fits Pre-Alpha, Alpha One, MC-1, R, and MR models within the specified serial number ranges.

Technical Specs

Product Type

Water Pump Impeller Repair Kit

Installation

Direct Replacement

Materials

Plastic (Housing), Neoprene (Impeller)

Impeller Design

Short-vane

Weight

0.37 kg (0.8 lb)

What’s in the Box

• 1 x Water Pump Impeller (47-89984T4)
• 1 x Pump Housing Assembly (46-96148A1)
• 1 x Wear Plate (32435)
• 1 x Water Tube Gasket (23-29804)
• 1 x Grommet (26-38970)
• 1 x Face Seal (26-45577)
• 7 x Assorted Gaskets (27-42631-1, 26-20260, 12-19183, 27-85610-1, 27-85608-1, 27-85609-1, 27-32438)

Installation Notes

1. Disconnect Power: Disconnect the battery and shift the outboard into neutral gear.
2. Drain Gearcase: Place a drain pan under the lower unit and remove the drain/fill plugs to empty the gearcase oil.
3. Remove Lower Unit: Loosen and remove the bolts securing the lower unit (gearcase) to the engine's midsection. Carefully separate the lower unit.
4. Access the Pump: With the lower unit removed, locate and unbolt the water pump housing.
5. Replace Components: Remove the old impeller, housing, wear plate, and gaskets. Clean all mating surfaces thoroughly.
6. Install New Kit: Install the new components in reverse order. Lightly grease the new impeller and insert it while turning the driveshaft clockwise to bend the vanes correctly.
7. Reassemble: Reinstall the water pump housing, ensuring all seals and gaskets are correctly seated. Torque bolts to manufacturer specifications.
8. Reattach Lower Unit: Guide the lower unit back into place, ensuring the driveshaft, shift shaft, and water tube align. Secure with bolts.
9. Refill and Test: Refill the gearcase with fresh oil. Reconnect the battery. Start the engine using a water supply (flushing muffs) and check for a steady stream of water from the tell-tale port.

Troubleshooting & FAQ

Safety & Important Info

• Verify images/specifications vs your original part. If anything differs—even if your model appears compatible—do not purchase.
• This is an aftermarket replacement, not an OEM component.
• Professional installation is recommended for safety and performance.

About Sea Sierra

• Pro-Grade Standards — We supply marine parts engineered to OEM-level tolerances and tested for real-world conditions.
• Fast Global Fulfillment — Free standard delivery to most regions in 5–15 days.
• Manufacturer-Direct Value — Fair pricing without compromising on materials or QC.