# 8M0090819 Mercury MerCruiser Mercury Thermostat Assembly | Genuine Quicksilver OEM Part

🔧 Product Description

  

Genuine Quicksilver 120°F Thermostat Assembly - Part Number: 8M0090819

  

Genuine Quicksilver 120°F thermostat and housing assembly used on Mercury 75HP to 115HP 2.1L FourStroke outboards. This assembly replaces / cross-references with 892864T06-style thermostat assemblies and is used on 65 Jet, 75HP, 90HP, 100HP and 115HP EFI FourStroke models where the cooling-system diagram specifies 8M0090819.

  

⚙️ Key Features

  

• Genuine Quicksilver OEM thermostat assembly

• Correct Mercury part number 8M0090819

• 120°F / approximately 50°C thermostat assembly

• Used on Mercury 75HP to 115HP 2.1L outboards

• Includes thermostat and housing assembly configuration

• Direct replacement for supported 2.1L EFI FourStroke cooling systems

  

🔄 Supersession & Cross Reference

  

OEM Supersession Chain:

  

• 8M0090819 current OEM thermostat and housing assembly reference

• 892864T06 earlier / related thermostat assembly reference where cross-listed

  

OEM / Related Numbers:

  

• 8M0090819

• 892864T06

• Mercury thermostat assembly

• 120°F thermostat assembly

• 50°C thermostat assembly

• 2.1L FourStroke thermostat housing

• Thermostat and housing assembly

• 25-8M0005958 related O-ring family reference

• 25-8M0153609 related grommet family reference

• 8M0204709 related water pump faceplate family reference

  

Aftermarket / Verified Equivalents:

  

• Aftermarket thermostat assembly replacements for 8M0090819 / 892864T06

• YM-8M0090819 aftermarket 50°C thermostat assembly equivalent

• Aftermarket Mercury 75HP-115HP 2.1L thermostat housing assemblies where matched by OEM number

• Use complete assembly match where the housing and thermostat are supplied together

  

🚤 Compatibility

  

Commonly used on:

  

• Mercury 75HP to 115HP 2.1L EFI FourStroke outboards

• Mercury SeaPro 75HP / 90HP / 115HP 2.1L cooling systems

• Thermostat service where housing assembly 8M0090819 is specified

  

Typically suits:

  

• Engine models:

• Mercury 65 Jet EFI 2.1L FourStroke - serial 2B095049 and up

• Mercury 75HP EFI FourStroke 2.1L - serial 2B095049 and up

• Mercury 75HP EFI SeaPro 2.1L - serial 2B095049 and up

• Mercury 90HP EFI FourStroke 2.1L - serial 2B095049 and up

• Mercury 90HP EFI SeaPro 2.1L - serial 2B095049 and up

• Mercury 100HP EFI FourStroke 2.1L - serial 2B095049 and up

• Mercury 115HP EFI FourStroke 2.1L - serial 2B095049 and up

• Mercury 115HP EFI Pro XS / SeaPro 2.1L applications where 8M0090819 is specified

• Mercury 75HP to 115HP 2.1L outboard cooling-system diagrams listing thermostat assembly 8M0090819

  

• HP Range: 65 Jet, 75HP, 90HP, 100HP and 115HP where specified

• Serial Range: commonly 2B095049 and up

• Engine Type: Mercury 2.1L EFI FourStroke outboard

• System Type: Thermostat and housing assembly

• Temperature Rating: 120°F / approximately 50°C

  

🔌 Function

  

The thermostat assembly regulates engine operating temperature by controlling cooling-water flow through the engine as it warms and operates under load.

  

Common signs of failure:

  

• Engine running too cold or too hot

• Overheat warning

• Temperature fault code

• Thermostat stuck open or closed

• Corrosion or salt deposits inside thermostat housing

• Cooling-system service requiring thermostat replacement

  

📦 Condition

  

• Genuine Quicksilver part

• Brand new

• Supplied in original or equivalent packaging

## Details

- **Price:** 114.25 AUD
- **Vendor:** Quicksilver
- **Tags:** Quicksilver Marine Parts | Oils Service Kits & Engine Components

## Variants

| Variant | Price | Available |
|---------|-------|-----------|
| Default Title | 114.25 AUD | In stock |

## Images

- 8M0090819 Mercury MerCruiser Mercury Thermostat Assembly | Genuine Quicksilver OEM Part
- 8M0090819 Mercury MerCruiser Mercury Thermostat Assembly | Genuine Quicksilver OEM Part

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> Source: [Sawley's Auto and Marine](https://www.sawleysautoandmarine.com.au/products/8m0090819-mercury-mercruiser-mercury-thermostat-assembly-genuine-quicksilver-oem-part)
> Updated: 2026-07-18