47-42038 Water Pump Impeller for Mercury Mariner | JLM Marine

Water Pump Impeller for Mercury Mariner 6, 8, 9.9, 10, 15 HP Outboard Motors

This high-performance water pump impeller is engineered for Mercury Mariner outboard engines rated at 6, 8, 9.9, 10, and 15 horsepower. Built with marine-grade neoprene rubber and corrosion-resistant hardened nylon, it ensures reliable cooling system operation across a wide range of Mercury models, including Marathon, SeaPro, Magnum, Bodensee, and Viking series.

Direct replacement for OEM part numbers: 47-42038, 47-42038-2, 47-420382, 47-42038Q02. Cross-compatible with aftermarket equivalents from Sierra (18-3062), CEF (500318), and Mallory (9-45309).

• 6-blade design for optimal water flow and engine cooling
• High-performance neoprene rubber construction resists marine and chemical corrosion
• Fits gear housing assemblies with 2.00:1 gear ratio driveshaft configurations

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.

Technical Specifications

Package Contents

This package includes:

• 1 × Water Pump Impeller

Installation Guide

1. Disconnect the fuel line and remove the engine cowling to access the lower unit. Ensure the outboard is in the upright position on a stable surface.
2. Drain the gear oil from the lower unit by removing the drain and vent plugs. Dispose of old oil properly.
3. Remove the propeller, cotter pin, and propeller nut to access the lower unit. Set hardware aside in a clean container.
4. Unbolt and separate the lower unit from the mid-section by removing the securing bolts. Carefully slide the unit away from the driveshaft.
5. Locate and remove the water pump housing cover by unscrewing the retaining bolts. Keep gaskets and seals for inspection.
6. Extract the old impeller from the pump housing using needle-nose pliers or a pick tool. Note the blade orientation for correct installation.
7. Clean the pump housing and inspect for damage or corrosion. Replace the housing if cracks or excessive wear are present.
8. Lubricate the new impeller blades with glycerin or soapy water (never petroleum-based products). Insert the impeller, aligning blades in the correct rotation direction.
9. Install a new gasket and reattach the pump housing cover. Torque bolts to manufacturer specifications in a cross pattern.
10. Reassemble the lower unit to the mid-section, ensuring the driveshaft engages properly. Reinstall and torque all mounting bolts.
11. Refill the lower unit with fresh gear oil through the bottom plug until oil flows from the top vent hole. Replace both plugs securely.
12. Reinstall the propeller, fuel line, and cowling. Test the engine in water to confirm proper cooling flow from the telltale outlet.

Troubleshooting & FAQ

How do I confirm this impeller fits my Mercury engine?
Verify your engine's serial number and horsepower rating against the compatibility table above. Cross-reference your original impeller part number (47-42038 or equivalents) to ensure an exact match.

How often should I replace the water pump impeller?
Replace the impeller annually or every 100–300 operating hours, whichever comes first. Inspect it more frequently if the engine operates in sandy, silty, or debris-laden water.

What are the signs of a failing impeller?
Common symptoms include weak or absent water flow from the telltale outlet, engine overheating, steam from the cowling, or a high-temperature alarm. Replace the impeller immediately if any of these occur.

Can I install this impeller myself, or do I need a mechanic?
If you have basic mechanical skills and tools, you can replace the impeller following the installation guide. However, professional installation is recommended if you're unfamiliar with lower unit service or lack proper torque tools.

What's the difference between this aftermarket impeller and the OEM version?
This 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.

How fast do you ship and how much does it cost?
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.

What is your warranty and return policy?
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.