Thermostat (120°F/50°C) – Fits Mercury Marine 6-125 HP Outboards (Replaces 14586)

Thermostat (120°F/50°C) – Fits Mercury Marine 6-125 HP Outboards (Replaces 14586)

This thermostat is engineered to fit a wide range of Mercury Marine 6-125 HP 2-Stroke outboards from 1986–2005, including standard, Sea Pro, Marathon, and Super models. It also offers compatibility with various Johnson/Evinrude 4-Stroke engines that use a similar mounting configuration.

It serves as a direct replacement for Mercury Marine part numbers 14586, 14586A3, 75692A9, 75692A10, and 75692A11. It also cross-references with Sierra 18-3549, GLM 13120/13130, Mallory 9-43014, AM AM435491, and Johnson/Evinrude 435491/0435491/0765559.

• Precise Temperature Control: Opens at a consistent 120°F (48.9°C) to ensure optimal engine operating temperature.
• Durable Construction: Made from high-quality brass with stainless steel components for corrosion resistance and longevity.
• Direct-Fit Installation: Designed as a direct replacement for the OEM thermostat, ensuring a straightforward installation process.

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.

For Johnson/Evinrude owners, here’s a guide to help you identify your engine’s serial/model: Johnson Serial Number Guide.

Technical Specifications

Package Contents

Please check your selection carefully before ordering. This product is available in two options:

• Thermostat Only (Replaces 14586):
  • 1 x Thermostat (14586)
• Complete Kit (Replaces 14586A3):
  • 1 x Thermostat (14586)
  • 1 x Gasket (27-62386)
  • 1 x Gasket (27-14318-3)
  • 1 x Gasket (27-19205-1)

Installation Guide

Follow these general steps to replace your outboard engine's thermostat. Always consult your engine's service manual for specific instructions.

1. Safety First: Ensure the engine is completely cool and disconnected from the battery.
2. Locate Housing: Find the thermostat housing on the engine block or cylinder head.
3. Remove Cover: Loosen and remove the bolts securing the housing cover. Note their positions if they are different lengths.
4. Access Thermostat: Carefully lift the cover. The thermostat and its gasket will be visible inside.
5. Remove Old Thermostat: Take out the old thermostat. It may be helpful to note its orientation.
6. Clean Surfaces: Thoroughly clean the mating surfaces of the housing and cover, removing all old gasket material.
7. Install New Gaskets: Place the new gaskets in their correct positions. If you purchased the full kit, use the gaskets provided.
8. Insert New Thermostat: Place the new thermostat into the housing, ensuring it is correctly oriented.
9. Replace Cover: Re-seat the housing cover and tighten the bolts in a crisscross pattern to the manufacturer's specified torque.
10. Test for Leaks: Reconnect the battery, start the engine using a water supply (flushing muffs), and check for any leaks around the housing as the engine warms up.

Troubleshooting & FAQ

Q: How do I know if this thermostat will fit my specific engine?

A: The best way to ensure fitment is to check your engine's serial number against the ranges listed in the "Compatible Engine Models" table. You can also verify by matching your old part number to the ones in our "Part Number Cross-Reference" list.

Q: What are the signs of a failing thermostat?

A: Common signs include engine overheating, the engine taking too long to reach operating temperature, or erratic temperature gauge readings. A thermostat stuck open will prevent the engine from warming up properly, while one stuck closed will cause overheating.

Q: Why is the 120°F temperature rating important?

A: The temperature rating ensures your engine warms up to its optimal operating temperature quickly and maintains it. Using the correct temperature thermostat is critical for engine performance, fuel efficiency, and longevity.

Q: OEM vs. Aftermarket?

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.