# 14586 Mercury MerCruiser Thermostat 120 Degree | Genuine Quicksilver OEM Part

🔧 Product Description

  

Genuine Quicksilver 120°F Thermostat - Part Number: 14586

  

A genuine Quicksilver 120°F thermostat for Mercury and Mariner outboards. This thermostat opens at 120 degrees Fahrenheit and is used in compatible 2-stroke and 4-stroke cooling systems from small outboards through selected mid-range 125HP models where the thermostat diagram specifies 14586.

  

⚙️ Key Features

  

• Genuine Quicksilver OEM thermostat

• Correct Mercury part number 14586

• 120°F opening temperature

• Used on Mercury / Mariner outboard cooling systems

• Cross-references with Sierra 18-3549 for matched applications

  

🔄 Supersession & Cross Reference

  

OEM Supersession Chain:

  

• 14586 current OEM thermostat reference

• 14586A3 related thermostat kit reference where supplied with gaskets

  

OEM / Related Numbers:

  

• 14586

• 14586A3

• Q14586

• 14586Q

• Mercury 120°F thermostat reference

• Thermostat kit reference for Mercury / Mariner 6HP to 25HP 2-cycle applications

  

Aftermarket / Verified Equivalents:

  

• Sierra: 18-3549

• Aftermarket thermostat 120°F equivalents exist for 14586 applications where matched by engine serial number

  

🚤 Compatibility

  

Commonly used on:

  

• Mercury / Mariner 2-stroke outboard thermostat housings

• Mercury / Mariner 40HP to 60HP 4-stroke thermostat housings where specified

• Mercury / Mariner 3-cylinder and 4-cylinder cooling systems requiring 120°F thermostat 14586

  

Typically suits:

  

• Engine models:

• Mercury / Mariner 6HP - serial A197112 and up, 1986-2003 USA and Belgium models

• Mercury / Mariner 7.5HP cooling system applications where thermostat 14586 is specified

• Mercury / Mariner 8HP - serial A197112 and up, 1986-2003 USA and Belgium models

• Mercury / Mariner 9.9HP - serial A197112 and up, 1986-2003 USA and Belgium models

• Mercury / Mariner 15HP - serial 0B292414 and up, 1988-2016 USA and Belgium models

• Mercury / Mariner 18HP XD - serial 6443973 to 0B238463, 1982-1986

• Mercury / Mariner 20HP - serial 0B238464 and up, 1988-2006

• Mercury / Mariner 25HP - serial 5705532 and up, 1984-2006 USA and Belgium models

• Mercury / Mariner 40HP 4-stroke - serial 0T178500 to 0T598999, 2003-2016

• Mercury / Mariner 40HP EFI 4-stroke - serial 0T409000 and up, 2003-2016

• Mercury / Mariner 50HP 3-cylinder - serial 0D000750 to 0G589999, 1990-2015

• Mercury / Mariner 50HP 4-stroke - serial 0T178500 and up, 2003-2016

• Mercury / Mariner 60HP 3-cylinder - serial 0D000750 and up, 1990-2015

• Mercury / Mariner 60HP 4-stroke - serial 0T178500 and up, 2003-2016

• Mercury / Mariner 75HP 3-cylinder - serial 0C222000 and up, 1988-2015

• Mercury / Mariner 90HP 3-cylinder - serial 0G760300 and up, 1989-2015

• Mercury / Mariner 100HP 4-cylinder - serial 0B209468 and up, 1988-2002

• Mercury / Mariner 115HP 4-cylinder - serial 0C100000 and up, 1988-2005

• Mercury / Mariner 125HP 4-cylinder - serial 0D283222 and up, 1988-2005

  

• HP Range: commonly 6HP - 125HP where specified

• Engine Type: Mercury / Mariner 2-stroke and selected 4-stroke outboard

• System Type: Cooling system thermostat

• Opening Temperature: 120°F / approximately 49°C

  

🔌 Function

  

The thermostat controls engine operating temperature by restricting or allowing cooling water flow as the engine warms up and runs under load.

  

Common signs of failure:

  

• Engine running too cold

• Overheating due to stuck thermostat

• Weak tell-tale flow after warm-up

• Salt or debris build-up around thermostat

• Thermostat stuck open or closed

• Temperature fluctuation at idle or under load

  

📦 Condition

  

• Genuine Quicksilver part

• Brand new

• Supplied in original or equivalent packaging

## Details

- **Price:** 72.0 AUD
- **Vendor:** Quicksilver
- **Tags:** Quicksilver Marine Parts | Oils Service Kits & Engine Components

## Variants

| Variant | Price | Available |
|---------|-------|-----------|
| Default Title | 72.00 AUD | In stock |

## Images

- 14586 Mercury MerCruiser Thermostat 120 Degree | Genuine Quicksilver OEM Part

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> Source: [Sawley's Auto and Marine](www.sawleysautoandmarine.com.au/products/14586-mercury-mercruiser-thermostat-120-degree-genuine-quicksilver-oem-part)
> Updated: 2026-05-17