# 27803508 Mercury MerCruiser Gasket | Genuine Quicksilver OEM Part

🔧 Product Description

  

Genuine Quicksilver Cylinder Head Gasket - Part Number: 27-803508

  

A genuine Quicksilver cylinder head gasket for Mercury / Mariner 4HP, 5HP and 6HP four-stroke outboards. This gasket seals the cylinder head to the block and is replaced during cylinder head removal, top-end inspection or engine resealing.

  

⚙️ Key Features

  

• Genuine Quicksilver OEM cylinder head gasket

• Correct Mercury part number 27-803508

• Used on Mercury / Mariner 4HP, 5HP and 6HP four-stroke outboards

• Also cross-referenced with Tohatsu / Nissan small outboard gasket reference 3H6-01005-1

• Required replacement gasket when the cylinder head is removed

  

🔄 Supersession & Cross Reference

  

OEM Supersession Chain:

  

• 27-803508 current OEM service reference

  

OEM / Related Numbers:

  

• 27-803508

• 803508

• 27803508

  

Aftermarket / Verified Equivalents:

  

• Tohatsu / Nissan: 3H6-01005-1

  

🚤 Compatibility

  

Commonly used on:

  

• Mercury / Mariner 4-stroke small outboard cylinder head gasket applications

• 4HP, 5HP and 6HP cylinder block / cylinder head assemblies where 27-803508 is specified

  

Typically suits:

  

• Engine models:

• Mercury 4HP 4-stroke - serial 0P073456 to 0P400999

• Mercury 4HP 4-stroke - serial 0P401000 to 0R411837

• Mercury 4HP 4-stroke - serial 0R000001 to 0R067089

• Mercury 4HP 4-stroke - serial 0R067090 to 0R411837

• Mercury 4HP 4-stroke - serial 0R411838 and up

• Mercury 5HP 4-stroke - serial 0P073456 to 0P400999

• Mercury 5HP 4-stroke - serial 0P401000 to 0R411837

• Mercury 5HP 4-stroke - serial 0R000001 to 0R067089

• Mercury 5HP 4-stroke - serial 0R067090 to 0R411837

• Mercury 5HP 4-stroke - serial 0R411838 and up

• Mercury 5HP 4-stroke JCI - serial 0R560794 and up

• Mercury 5HP Propane - serial 0R936270 and up

• Mercury 6HP 4-stroke - serial 0P073456 to 0P400999

• Mercury 6HP 4-stroke - serial 0P401000 to 0R411837

• Mercury 6HP 4-stroke - serial 0R000001 to 0R067089

• Mercury 6HP 4-stroke - serial 0R067090 to 0R411837

• Mercury 6HP 4-stroke - serial 0R411838 and up

  

• HP Range: 4HP - 6HP

• Engine Type: Mercury / Mariner single-cylinder four-stroke outboard

• System Type: Cylinder head to block gasket

  

🔌 Function

  

The cylinder head gasket seals combustion pressure, cooling passages and oil-return areas between the cylinder head and engine block.

  

Common signs of failure:

  

• Compression loss

• Overheating

• Water or oil contamination

• Poor starting or rough running

• Gasket replacement required after cylinder head removal

  

📦 Condition

  

• Genuine Quicksilver part

• Brand new

• Supplied in original or equivalent packaging

## Details

- **Price:** 30.65 AUD
- **Vendor:** Quicksilver
- **Tags:** Quicksilver Marine Parts | Oils Service Kits & Engine Components

## Variants

| Variant | Price | Available |
|---------|-------|-----------|
| Default Title | 30.65 AUD | In stock |

## Images

- 27803508 Mercury MerCruiser Gasket | Genuine Quicksilver OEM Part

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> Source: [Sawley's Auto and Marine](www.sawleysautoandmarine.com.au/products/27803508-mercury-mercruiser-gasket-genuine-quicksilver-oem-part)
> Updated: 2026-05-17