Water Pump Impeller Repair Kit – Fits Mercury/Mariner Outboards 65-225 HP & MerCruiser Alpha One Gen I

Water Pump Impeller Repair Kit – Fits Mercury/Mariner Outboards 65-225 HP & MerCruiser Alpha One Gen I (Replaces 96148Q8, 96148A8)

This water pump impeller repair kit is designed for a wide range of Mercury/Mariner Outboards and MerCruiser Stern Drives. It is compatible with 65-225 HP 2-Stroke Mercury/Mariner outboards (4-cylinder through V6 models) from the 1970s–1990s that use short vane impellers. It also fits MerCruiser I, R, MR, and Alpha One Gen I stern drives (S/N 2495186 through 0D469858) from the same era.

This kit serves as a direct replacement for multiple OEM and aftermarket part numbers, including Mercury 46-96148Q8, 96148T8, 96148A8, 96148A5, 42579A4, 44292A4, 48747A3, 32437A1, 37433A1; Sierra 18-3517; and Mallory 9-48311.

• Engineered for higher flow rates to improve cooling performance.
• Includes a plastic pump housing and all necessary components for a complete overhaul.
• Installs in the lower unit (outdrive) of the engine.

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.

Mercury/Mariner Outboards

MerCruiser Stern Drives

Technical Specifications

Package Contents

• 1 x Water Pump Impeller (89984T4)
• 1 x Plastic Pump Housing (96148A1)
• 1 x Face Plate (8M0204677)

Installation Guide

1. Disconnect Power: Disconnect the negative battery cable before beginning work.
2. Drain Gear Oil: Place a drain pan under the lower unit and remove the upper and lower drain/vent screws to drain the gearcase oil.
3. Remove Lower Unit: Remove the bolts securing the lower unit to the engine. Carefully separate the lower unit from the engine assembly.
4. Disassemble Pump: Unbolt and remove the old water pump housing to access the impeller and wear plate. Note the orientation of the old impeller vanes.
5. Clean Surfaces: Thoroughly clean the driveshaft and the mounting surfaces of any old gasket material or debris.
6. Install New Components: Install the new gaskets and face plate. Slide the new impeller onto the driveshaft, rotating it in the direction of engine rotation to correctly orient the vanes. Apply a light coat of grease to help.
7. Install New Housing: Place the new pump housing over the impeller and bolt it down to the specified torque.
8. Reinstall Lower Unit: Carefully guide the lower unit back into place, ensuring the driveshaft, water tube, and shift shaft are correctly aligned. Secure it with the mounting bolts.
9. Refill Gear Oil: Fill the gearcase with fresh marine gear lube through the bottom hole until it flows out of the top hole. Reinstall both vent and fill screws.
10. Test Operation: Reconnect the battery. Start the engine using a water supply (flushing muffs) and confirm a steady stream of water is exiting the tell-tale port.

Troubleshooting & FAQ

Q: How do I confirm this kit fits my engine?

A: To ensure compatibility, please check your engine's model, horsepower, and serial number against the models listed in our "Compatible Engine Models" table. You can also compare your existing part numbers with those in the "Part Number Cross-Reference" table. For Mercury/MerCruiser models, using the serial number is the most reliable way to verify fitment.

Q: What are the signs of a failing water pump impeller?

A: The most common signs of a worn or damaged impeller are engine overheating, especially at low speeds, and a weak or nonexistent water stream from the engine's tell-tale outlet. You may also find melted plastic pieces from the housing in the cooling system if it has severely failed.

Q: How often should the impeller be replaced?

A: As a critical preventative maintenance item, we recommend inspecting the impeller annually and replacing it every 1-2 years or every 100-200 hours of engine use. Replacement frequency should be increased for boats operating in saltwater or in water with heavy sediment.

Q: Is this an OEM part?

A: This is a high-quality aftermarket replacement part, not an OEM component. It is designed to meet or exceed OEM specifications and is manufactured in an ISO 9002-certified facility to ensure consistent performance and reliability.

Q: How fast do you ship and what are the costs?

A: We offer free standard shipping worldwide, with most orders arriving within 5-15 business days. Expedited shipping options are also available at checkout for an additional fee, depending on your location.

Q: What is your warranty and return policy?

A: This product is backed by a 1-year warranty against any manufacturing defects under normal operating conditions. If you encounter an issue, please contact our support team with your order details. We accept returns for unused items in their original packaging within our standard return period; see our policy page for more details.

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.