8M0120836 Maintenance Kit for Mercury Mariner Quicksilver 4HP 5HP 6HP | JLM Marine

Maintenance Kit for Mercury Mariner Quicksilver 4HP 5HP 6HP – OEM 8M0120836

This comprehensive maintenance kit is designed for Mercury Mariner Quicksilver 4HP, 5HP, and 6HP 4-Stroke outboard motors. It provides essential service components including a water pump impeller, thermostat, fuel filter, seals, and gaskets—everything you need for routine maintenance in one convenient package.

Direct replacement for Mercury OEM part number 8M0120836, this kit fits models 0R411837 and below as well as 0R411838 and above, ensuring broad compatibility across the 4/5/6 HP 4-stroke series.

• Complete maintenance solution with 10+ components for comprehensive service
• Includes critical wear items: water pump impeller, thermostat, fuel filter, and seals
• Fits both early and late model Mercury 4/5/6 HP 4-stroke outboards

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 (Part No. 47-16154-3)
• 1× Cotter Pin (Part No. 815026)
• 1× Pin Key (Part No. 28-16155)
• 1× Thermostat (Part No. 804540)
• 1× Thermostat Gasket (Part No. 27-8M0214960)
• 1× O-ring (Part No. 25-16131)
• 1× Oil Seal (Part No. 16130 / 26-16130)
• 1× Fuel Filter (Part No. 35-8M0157133)
• 3× Drain Gaskets (Part No. 12-8035161 & 8M0075255)

Installation Guide

1. Prepare the engine: Disconnect the fuel line and remove the engine cowling to access the powerhead and lower unit.
2. Remove the lower unit: Drain the gear oil, then unbolt and carefully separate the lower unit from the mid-section.
3. Replace the water pump impeller: Remove the old impeller housing, install the new impeller (Part No. 47-16154-3) with key and pin, and reassemble the housing with fresh gaskets.
4. Install new seals and O-rings: Replace the oil seal (Part No. 26-16130) and O-ring (Part No. 25-16131) in the lower unit.
5. Replace drain gaskets: Install new drain gaskets (Part No. 12-8035161 & 8M0075255) on both drain plugs before refilling gear oil.
6. Reinstall the lower unit: Align the driveshaft and water tube, then bolt the lower unit back onto the mid-section.
7. Replace the thermostat: Remove the thermostat cover on the powerhead, install the new thermostat (Part No. 804540) with its gasket (Part No. 27-8M0214960), and torque the cover bolts to specification.
8. Install the fuel filter: Disconnect the fuel line, remove the old filter, and install the new fuel filter (Part No. 35-8M0157133) ensuring proper flow direction.
9. Refill fluids: Add fresh lower unit gear oil through the bottom drain hole until it flows from the top vent, then install both drain plugs with new gaskets.
10. Reconnect and test: Reattach the fuel line, reinstall the cowling, and run the engine in a test tank to verify proper cooling water flow and no leaks.

Troubleshooting & FAQ

Q: How do I confirm this kit fits my Mercury outboard?
A: Check your engine's serial number plate; this kit fits Mercury/Mariner/Quicksilver 4HP, 5HP, and 6HP 4-stroke models with serial numbers 0R411837 and below, as well as 0R411838 and above. Verify your model against the compatibility table above.

Q: How often should I perform this maintenance?
A: Mercury recommends servicing the water pump impeller annually or every 100 hours of operation, whichever comes first. The thermostat and fuel filter should be inspected during this service and replaced as needed or every 2–3 years.

Q: What are the signs that my water pump or thermostat needs replacement?
A: Common symptoms include overheating, weak water flow from the telltale (pee hole), steam from the engine, or inconsistent operating temperature. If you notice any of these, inspect and replace the impeller and thermostat immediately.

Q: Can I install this kit myself or do I need a mechanic?
A: If you have basic mechanical skills and the right tools, you can perform this maintenance yourself following the service manual. However, professional installation is recommended if you're unfamiliar with lower unit removal or torque specifications.

Q: Does this kit include all the gaskets I need?
A: This kit includes the thermostat gasket, drain gaskets, O-ring, and oil seal. Depending on your engine's condition, you may need additional gaskets (such as lower unit housing gaskets), which are typically sold separately.

Q: Is this an OEM or aftermarket kit?
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.