8M0120867 Maintenance Kit for Mercury 8HP 9.9HP 15HP 20HP Command Thrust | JLM Marine

8M0120867 Maintenance Kit for Mercury 8HP 9.9HP 15HP 20HP Command Thrust | JLM Marine

This comprehensive maintenance kit is engineered for Mercury 8HP, 9.9HP, 15HP, and 20HP Command Thrust outboard engines within the serial range 0R235949-0R833819. It consolidates all essential service components—impeller, thermostats, filters, gaskets, and anodes—into one complete package, streamlining routine maintenance and ensuring optimal engine performance.

Direct Replacement: OEM part number 8M0120867. This aftermarket kit matches OEM specifications, delivering reliable performance at a competitive price point.

• Complete Service Solution: Includes impeller, thermostat assembly, fuel & oil filters, gaskets, anode, and gear oil pump—everything needed for a full maintenance cycle.
• Wide HP Range: Fits 8HP through 20HP Command Thrust models within the specified serial range.
• OEM-Spec Construction: Manufactured to meet Mercury's dimensional and material standards for drop-in compatibility.

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:

• 8M0075040 – Gasket × 1
• 803753 – Guide Plate × 1
• 803751 – Insert × 1
• 803749 – Key × 1
• 803748 – Impeller × 1
• 823042046 – Screw × 3
• 8M0119207 – Thermostat × 1
• 27-853702005 – Thermostat Gasket × 1
• 35-8M0157133 – Fuel Filter × 1
• 35-822626Q03 – Oil Filter × 1
• 12-895146 – Gasket × 1
• 12-191833 – Drain Gasket × 2
• 27-95220 – Drain Gasket × 2
• 8150264 – Cotter Pin × 1
• 823912 – Anode × 1
• 24OP149 – Gear Oil Pump × 1

Installation Guide

1. Preparation: Disconnect the fuel line and place the engine in an upright, stable position. Gather necessary tools including screwdrivers, wrenches, and a drain pan.
2. Remove Lower Unit: Drain the gear oil using the drain screws and collect it in a pan. Unbolt and carefully separate the lower unit from the mid-section.
3. Access Water Pump Housing: Remove the water pump housing cover by unscrewing the retaining bolts. Take note of the orientation of components for reassembly.
4. Replace Impeller: Remove the old impeller, insert, key, and guide plate. Install the new key (803749), insert (803751), impeller (803748), and guide plate (803753) in the correct orientation.
5. Install Gaskets: Replace all old gaskets with the new ones provided (8M0075040, 12-895146, 12-191833, 27-95220). Ensure mating surfaces are clean and free of debris.
6. Replace Thermostat: Locate the thermostat housing, remove the old thermostat, and install the new thermostat (8M0119207) along with its gasket (27-853702005).
7. Change Fuel & Oil Filters: Replace the fuel filter (35-8M0157133) in the fuel line and the oil filter (35-822626Q03) at its mounting location. Hand-tighten securely.
8. Install Anode: Replace the sacrificial anode (823912) on the lower unit or engine bracket. This protects metal components from galvanic corrosion.
9. Reassemble Water Pump: Secure the water pump housing with the provided screws (823042046) and tighten in a crisscross pattern to ensure even sealing.
10. Reattach Lower Unit: Using the gear oil pump (24OP149), refill the lower unit with the manufacturer-recommended gear oil until it flows from the upper vent. Reinstall drain gaskets and secure the lower unit to the mid-section.
11. Reconnect & Test: Reconnect the fuel line, check all fasteners for tightness, and inspect for any leaks. Start the engine in a test tank or on-water and confirm proper water flow from the tell-tale.
12. Final Inspection: Run the engine at idle for several minutes, then increase throttle gradually. Monitor for overheating, unusual vibrations, or leaks and address any issues immediately.

Troubleshooting & FAQ

Q: How do I confirm this kit fits my Mercury outboard?
A: Verify your engine's serial number falls within the range 0R235949-0R833819 and that your engine is an 8HP, 9.9HP, 15HP, or 20HP Command Thrust model. Cross-reference with the Compatible Engine Models table above or consult your engine's service manual.

Q: How often should I replace the components in this maintenance kit?
A: Mercury recommends inspecting the impeller annually and replacing it every 2–3 years or 200–300 operating hours, whichever comes first. Thermostats, filters, and anodes should be replaced at similar intervals or whenever signs of wear, corrosion, or clogging are observed.

Q: What are the signs that my impeller or thermostat needs replacement?
A: Impeller failure typically shows as reduced water flow from the tell-tale, overheating alarms, or visible damage (cracked/missing vanes). A faulty thermostat may cause the engine to run too cool (poor fuel economy, sluggish performance) or overheat (steam, alarm).

Q: Can I reuse any of the old gaskets or filters?
A: No. Gaskets compress and deform during initial installation, and reusing them can lead to leaks. Filters accumulate contaminants over time and must be replaced to maintain proper fuel and oil flow.

Q: Do I need any special tools to install this maintenance kit?
A: Basic hand tools (screwdrivers, socket set, pliers) are sufficient for most steps. The included gear oil pump (24OP149) simplifies lower unit refilling. A service manual for your specific engine model is highly recommended.

Q: Is this an OEM or aftermarket part?
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.