# 278503181 Mercury MerCruiser Gasket | Genuine Quicksilver OEM Part

🔧 Product Description

  

Genuine Quicksilver Thermostat Gasket - Part Number: 27-8503181

  

A genuine Quicksilver thermostat gasket for Mercury V6 3.0L and 3.2L EFI / DFI outboards and SportJet Jet Drive applications. This gasket seals the thermostat cover area in high-output outboard cooling systems and is replaced during thermostat inspection or cooling-system service.

  

⚙️ Key Features

  

• Genuine Quicksilver OEM thermostat gasket

• Correct Mercury part number 27-8503181

• Used on Mercury 200HP, 225HP, 250HP and 300HP V6 EFI / DFI applications where specified

• Also used on 250 DFI Jet Drive and 250 DFI M2 Jet Drive applications

• Important thermostat cover gasket for 3.0L and 3.2L Mercury V6 cooling systems

  

🔄 Supersession & Cross Reference

  

OEM Supersession Chain:

  

• 27-8503181 current OEM service reference

  

OEM / Related Numbers:

  

• 27-8503181

• 8503181

• 278503181

  

Aftermarket / Verified Equivalents:

  

• No aftermarket equivalent

  

🚤 Compatibility

  

Commonly used on:

  

• Mercury V6 EFI and DFI / OptiMax thermostat gasket applications

• Mercury 3.0L and 3.2L high-output outboard cooling systems where 27-8503181 is specified

  

Typically suits:

  

• Engine models:

• Mercury 250 DFI Jet Drive powerhead - serial 0E407100 and up

• Mercury 250 DFI Jet Drive pump - serial 0E407100 and up

• Mercury 250 DFI M2 Jet Drive powerhead - serial 0E407100 and up

• Mercury 250 DFI M2 Jet Drive pump - serial 0E407100 and up

• Mercury 225 Sport XS - serial 1E002584 and up

• Mercury 225 Sport XS 3.0L - serial 1E000797 to 1E002583

• Mercury 225 XS - serial 1E002584 and up

• Mercury 250 Sport XS - serial 1E002342 to 1E051823

• Mercury 250 Sport XS - serial 1E051824 and up

• Mercury 250XS 3.0L DFI - serial 0T651945 to 0T818042

• Mercury 250XS 3.0L DFI - serial 0T818043 to 0T997973

• Mercury 250XS 3.0L DFI - serial 0T997974 to 1E000796

• Mercury 250XS 3.0L DFI - serial 1E000797 to 1E002341

• Mercury 250XS 3.0L DFI - serial 1E002342 to 1E051113

• Mercury 300X 3.0L EFI Pro Max - serial 0T235084 to 0T429939

• Mercury 300X 3.0L EFI Pro Max - serial 0T429940 to 0T999587

• Mercury 300XS 3.2L DFI - serial 1E001867 to 1E052057

• Mercury JP 3.0L DFI - serial 0T997974 to 1E003045

• Mercury JP 3.0L DFI - serial 1E003046 and up

• Mercury 200 3.0L DFI DTS - serial 0T980000 to 1B417701

• Mercury 200 3.0L DFI DTS - serial 1B417702 to 1B504988

• Mercury 200 3.0L DFI DTS - serial 1B504989 and up

• Mercury 200 3.0L EFI - serial 0T750164 to 0T800999

• Mercury 200 3.0L EFI - serial 0T801000 to 1B417701

• Mercury 200 3.0L EFI - serial 1B417702 to 1B504988

• Mercury 200 3.0L EFI - serial 1B504989 and up

• Mercury 200 DFI - serial 0G760300 to 0G960499

• Mercury 200 DFI - serial 0G960500 to 0T178499

• Mercury 200 DFI - serial 0T178500 to 0T598999

• Mercury 200 DFI - serial 0T599000 to 0T800999

• Mercury 200 DFI 3.0L - serial 0T801000 to 1B417701

• Mercury 200 DFI 3.0L - serial 1B417702 to 1B504988

• Mercury 200 DFI 3.0L - serial 1B504989 to 1B912785

• Mercury 200 DFI 3.0L - serial 1B912786 and up

• Mercury 200 Pro XS DFI 3.0L - serial 1B504989 to 1B912785

• Mercury 200 Pro XS DFI 3.0L - serial 1B912786 and up

• Mercury 225 3.0L EFI - serial 0T409000 to 0T800999

• Mercury 225 3.0L EFI - serial 0T801000 to 1B417701

• Mercury 225 3.0L EFI - serial 1B417702 to 1B504988

• Mercury 225 3.0L EFI - serial 1B504989 and up

• Mercury 225 3.0L EFI Marathon - serial 0T801000 to 1B417701

• Mercury 225 3.0L EFI SeaPro - serial 0T801000 to 1B417701

• Mercury 225 DFI 3.0L - serial 0T801000 to 1B417701

• Mercury 225 DFI 3.0L - serial 1B417702 to 1B504988

• Mercury 225 DFI 3.0L - serial 1B504989 and up

• Mercury 225 Pro XS 3.0L DFI - serial 1B104549 to 1B426560

• Mercury 225 Pro XS 3.0L DFI - serial 1B426561 to 1B752546

• Mercury 225 Pro XS 3.0L DFI - serial 1B752547 and up

• Mercury 250 3.0L EFI - serial 0T409000 to 0T800999

• Mercury 250 3.0L EFI - serial 0T801000 to 1B417701

• Mercury 250 3.0L EFI - serial 1B417702 to 1B504988

• Mercury 250 3.0L EFI - serial 1B504989 and up

• Mercury 250 DFI 3.0L - serial 1B528615 and up

• Mercury 250 Long 3.0L EFI - serial 0T861319 and up

• Mercury 250 Pro XS 3.0L DFI - serial 1B426561 to 1B752546

• Mercury 250 Pro XS 3.0L DFI - serial 1B752547 and up

• Mercury 3.0L EFI Marathon - serial 0T409000 to 0T800999

• Mercury 3.0L EFI SeaPro - serial 0T409000 to 0T800999

  

• HP Range: commonly 200HP - 300HP where specified

• Engine Type: Mercury V6 3.0L / 3.2L EFI and DFI outboard

• System Type: Thermostat gasket / cooling-system cover gasket

  

🔌 Function

  

The thermostat gasket seals the thermostat cover area so the cooling system can regulate engine temperature without leakage or pressure loss at the thermostat joint.

  

Common signs of failure:

  

• Water leak around thermostat cover

• Salt build-up near thermostat housing

• Overheating or unstable operating temperature

• Gasket tearing during thermostat service

• Replacement required after thermostat cover removal

  

📦 Condition

  

• Genuine Quicksilver part

• Brand new

• Supplied in original or equivalent packaging

## Details

- **Price:** 7.9 AUD
- **Vendor:** Quicksilver
- **Tags:** Quicksilver Marine Parts | Oils Service Kits & Engine Components

## Variants

| Variant | Price | Available |
|---------|-------|-----------|
| Default Title | 7.90 AUD | In stock |

## Images

- 278503181 Mercury MerCruiser Gasket | Genuine Quicksilver OEM Part

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> Source: [Sawley's Auto and Marine](www.sawleysautoandmarine.com.au/products/278503181-mercury-mercruiser-gasket-genuine-quicksilver-oem-part)
> Updated: 2026-05-17