Water Pump Impeller Kit – Fits Mercury/Mercruiser Alpha One & Outboard Motors (Replaces 46-96148A8, 96148Q8)

Water Pump Impeller Kit – Fits Mercury/Mercruiser Alpha One & Outboard Motors

This water pump impeller repair kit is designed for Mercury/Mercruiser Alpha One sterndrive units (1983–1990) and a wide range of Mercury outboard motors from 65 HP to 220 HP that use short-vane impellers. It serves as a comprehensive solution for replacing worn or damaged water pump components to prevent engine overheating.

This kit is a direct replacement for multiple OEM and aftermarket part numbers, including Mercury 46-96148A8, 96148Q8, 46-96148T8, 46-96148A5, 46-42579A4, 46-44292A4, 46-48747A3, Sierra 18-3320, GLM 12120, and Mallory 9-48307.

• Includes a durable neoprene impeller and PA66 nylon housing.
• Engineered as a direct-fit replacement for straightforward installation.
• Complete with all necessary gaskets, seals, and o-rings for a full service.

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.

Confirm your engine model/year in the table below. For Johnson/Evinrude owners, here’s a guide to help you identify your engine’s serial/model: Johnson/Evinrude Serial Number Guide.

Mercury Outboard Motors

Mercury MerCruiser Stern Drives

Johnson/Evinrude Applications

Technical Specifications

Package Contents

• 1 x Water Pump Impeller
• 1 x Pump Housing (Upper)
• 1 x Face Plate
• 1 x Drive Key (or Pin)
• 1 x Face Seal
• 1 x Seal Carrier
• 1 x Water Tube Coupling
• 1 x Set of Gaskets
• 1 x Set of O-Rings
• 2 x Gearlube Fill & Vent Screw Seals

Note: Pump base assembly is not included in this kit.

Installation Guide

1. Safety First: Disconnect the boat's battery before beginning any work.
2. Drain Lubricant: Place a drain pan under the lower unit and remove the drain/fill screws to empty the gearcase lubricant.
3. Remove Lower Unit: Unbolt and carefully detach the lower unit (gearcase) from the engine's upper assembly.
4. Access Pump: Unscrew the bolts securing the water pump housing to the lower unit.
5. Remove Old Components: Lift off the old housing. Remove the impeller, wear plate, and gaskets. Note their orientation.
6. Clean Surfaces: Thoroughly clean the mounting surface on the gearcase, removing any old gasket material or debris.
7. Install New Kit: Place the new gasket and wear plate. Slide the new impeller onto the drive shaft (turn clockwise) and install the drive key.
8. Reassemble Pump: Fit the new housing over the impeller and bolt it down to the specified torque.
9. Reattach Lower Unit: Guide the lower unit back into place, ensuring the driveshaft, shift shaft, and water tube align correctly. Secure with bolts.
10. Refill Lubricant: Fill the gearcase with the recommended marine gear lubricant from the bottom hole until it emerges from the top hole. Re-install both screw seals.
11. Test Operation: Reconnect the battery. Safely start the engine in water and confirm a steady stream of water from the "tell-tale" exhaust port.

Troubleshooting & FAQ

Q: How do I confirm this kit fits my engine?
A: This kit is designed for Mercury/Mercruiser Alpha One sterndrives (1983-1990) and various 65-220 HP outboards. Please check your model against the compatible engine tables and verify your serial number falls within the specified range (2491586 to 0D469858 for many Mercruiser models).

Q: Is the pump base included?
A: No, the base assembly is not included in this kit. This kit contains the upper plastic housing, impeller, face plate, gaskets, and related seals as listed in the 'Package Contents' section.

Q: What are common signs that my impeller needs replacing?
A: Common indicators include engine overheating, a weak or non-existent stream of water from the "tell-tale" outlet, or visible damage like cracked, stiff, or brittle impeller vanes found during inspection.

Q: What is the difference between this kit and the OEM part?
A: This is an aftermarket replacement part built to meet or exceed original equipment specifications using high-quality neoprene rubber for the impeller and PA66 nylon for the housing. It serves as a direct replacement for multiple OEM part numbers, including 46-96148A8 and 96148Q8.

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.