8M0120867 Maintenance Kit for Mercury Mariner 8HP 9.9HP Command Thrust EFI | JLM Marine

Maintenance Kit for Mercury Mariner 8HP 9.9HP Command Thrust EFI

This comprehensive maintenance kit is specifically designed for Mercury Mariner 8HP and 9.9HP Command Thrust EFI outboard motors (serial number 0R042475 and above). It includes all essential components to perform routine maintenance and ensure your engine runs at peak performance.

This kit serves as a direct replacement for OEM part numbers 8M0120867, 8M0120838, 3SA-87500-0, and 3RS-87500-0, providing a complete service solution in one convenient package.

• Includes water pump impeller, thermostat, fuel filter, oil filter, and gaskets
• Designed specifically for Command Thrust EFI models
• Complete maintenance solution for routine service intervals

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:

• 1× Water Pump Impeller (47-803748)
• 1× Key (8M0137347)
• 1× Thermostat (8M0119207)
• 1× Thermostat Gasket (27-8M0214960)
• 1× Fuel Filter (35-8M0157133)
• 1× Oil Filter (35-822626Q03)
• 1× Cotter Pin (951403-0310)
• 3× Drain Gaskets (12-895146 & 8M0075255)

Installation Guide

1. Preparation: Ensure the engine is off and cooled down completely. Gather all necessary tools including screwdrivers, wrenches, and a drain pan.
2. Oil Change: Remove the old oil filter using an oil filter wrench and drain the engine oil into a suitable container. Install the new oil filter (35-822626Q03) and replace drain gaskets before refilling with fresh oil.
3. Fuel Filter Replacement: Locate the fuel filter and disconnect fuel lines carefully. Replace with the new fuel filter (35-8M0157133) and ensure all connections are secure to prevent leaks.
4. Water Pump Service: Remove the lower unit to access the water pump housing. Carefully remove the old impeller and install the new impeller (47-803748) along with the key (8M0137347), ensuring proper orientation.
5. Thermostat Replacement: Remove the thermostat housing cover and take out the old thermostat. Install the new thermostat (8M0119207) with the new gasket (27-8M0214960) and torque the housing bolts to specification.
6. Final Assembly: Reinstall the lower unit, secure the cotter pin, and double-check all fasteners. Refill fluids to proper levels and run the engine to verify proper operation and check for leaks.

Troubleshooting & FAQ

Q: How do I confirm this maintenance kit fits my Mercury engine?
A: This kit is designed exclusively for Mercury Mariner 8HP and 9.9HP Command Thrust EFI models with serial number 0R042475 and above. Check your engine's serial number plate or consult the Mercury serial number guide linked above to verify compatibility.

Q: How often should I perform maintenance with this kit?
A: Mercury recommends performing routine maintenance every 100 hours of operation or annually, whichever comes first. For harsh operating conditions (saltwater, heavy use), consider more frequent service intervals to ensure optimal performance.

Q: Can I install this maintenance kit myself or do I need a professional?
A: While experienced boat owners with mechanical skills can perform this maintenance, professional installation is recommended to ensure proper torque specifications, impeller orientation, and leak-free assembly. Improper installation can lead to engine damage.

Q: What are signs that my water pump impeller needs replacement?
A: Common symptoms include weak water stream from the tell-tale, engine overheating, reduced cooling system performance, or visible damage to the impeller blades. Regular inspection and replacement prevent costly engine damage.

Q: Is this an OEM part or aftermarket replacement?
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.