8M0251126 Maintenance Kit for Mercury 40HP 50HP 3 Cylinder | JLM Marine

8M0251126 Maintenance Kit for Mercury 40HP 50HP 3 Cylinder | JLM Marine

This comprehensive maintenance kit is engineered for Mercury 40-50HP 3-cylinder outboard engines manufactured between 1994 and 2011 (serial number range 0G590000 to 2B999999). It consolidates essential service components—including water pump parts, thermostats, fuel filters, and lubrication accessories—into one package to simplify routine maintenance and extend engine life.

OEM Part Number: 8M0251126. This aftermarket kit delivers direct-fit replacement components that meet or exceed original equipment specifications, providing a cost-effective solution for scheduled service intervals.

• Complete cooling system refresh: impeller, gaskets, thermostat, and water tubes
• Includes fuel filter and gear oil pump for comprehensive drivetrain maintenance
• All components designed for precise fit on USA-model Mercury 3-cylinder engines

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 maintenance kit includes the following components:

• 47-85089-10 Water Pump Impeller × 1
• 8M0032838 / 85119 Impeller Key × 1
• 821354-2 Wear Plate × 1
• 27-822189 Gasket × 1
• 27-822217 Gasket × 1
• 12-86645-1 Washer × 2
• 823547 1 Water Tube × 1
• 43023 Water Tube × 1
• 850055001 Thermostat × 1
• 27-827284 Thermostat Gasket × 1
• 35-877565T1 Fuel Filter × 1
• 12-191833 Drain Screw Gasket × 3
• 27-828816 Oil Drain Screw Gasket × 1
• 24OP149 Gear Oil Pump × 1

Important: Verify all components match your engine's service manual specifications before installation.

Installation Guide

1. Preparation: Disconnect the battery and ensure the engine is cool. Gather necessary tools including screwdrivers, wrenches, and a torque wrench.
2. Access the Lower Unit: Remove the propeller and drain the gear oil using the drain screws. Replace drain screw gaskets (12-191833) during reassembly.
3. Remove Water Pump Housing: Unbolt the water pump housing from the lower unit. Carefully separate it to expose the old impeller and wear plate.
4. Replace Impeller & Wear Plate: Remove the old impeller (47-85089-10) and impeller key (8M0032838). Install the new wear plate (821354-2), then insert the new impeller with key aligned.
5. Install Gaskets: Replace all pump housing gaskets (27-822189, 27-822217) with new ones. Ensure mating surfaces are clean and free of old gasket material.
6. Replace Water Tubes: Install new water tubes (823547 1 and 43023) into their respective ports. Verify secure seating to prevent coolant leaks.
7. Thermostat Replacement: Locate the thermostat housing on the cylinder head. Remove the old thermostat (850055001) and gasket (27-827284), then install new components.
8. Fuel Filter Service: Replace the inline fuel filter (35-877565T1) in the fuel line. Ensure fuel flow direction matches the arrow on the filter housing.
9. Reassemble Water Pump: Torque all water pump housing bolts to manufacturer specifications. Install washers (12-86645-1) as directed in your service manual.
10. Refill Gear Oil: Use the included gear oil pump (24OP149) to refill the lower unit through the bottom drain hole. Fill until oil appears at the upper vent hole, then replace both drain plugs with new oil drain screw gasket (27-828816).
11. Final Checks: Reinstall the propeller and reconnect the battery. Run the engine in a test tank or on-water to verify proper cooling system operation and check for leaks.
12. Documentation: Record the service date and hours in your maintenance log. Dispose of used oil and filters according to local regulations.

Troubleshooting & FAQ

How do I confirm this kit fits my Mercury engine?
Verify your engine's serial number falls within the range 0G590000 to 2B999999 and that it is a USA-model 40-50HP 3-cylinder outboard manufactured between 1994 and 2011. Cross-reference with your owner's manual or use the Mercury serial number guide linked above.

How often should I replace the water pump impeller?
Mercury recommends replacing the water pump impeller every 2-3 years or 200-300 hours of operation, whichever comes first. Engines operated in sandy or silty water may require more frequent service.

What are the signs that my cooling system needs service?
Watch for reduced water stream from the telltale (pee hole), engine overheating alarms, steam from the engine, or poor performance. These symptoms often indicate impeller failure or thermostat issues.

Can I reuse the old gaskets if they look intact?
No, always replace all gaskets during service even if they appear undamaged. Used gaskets compress and lose their sealing ability, which can lead to coolant leaks and overheating.

What's the difference between this kit and the OEM Mercury kit?
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.

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.