# 128M0204722 Mercury MerCruiser 8M0204722 Washer | Genuine Quicksilver OEM Part

🔧 Product Description

  

Genuine Quicksilver Driveshaft / Impeller Washer - Part Number: 12-8M0204722

  

A genuine Quicksilver washer used in Mercury and Mariner outboard water pump assemblies. This transparent driveshaft washer fits between the impeller and driveshaft / water pump stack on compatible Mercury water pump applications and is commonly replaced during impeller or water pump service.

  

⚙️ Key Features

  

• Genuine Quicksilver OEM washer

• Correct current Mercury part number 12-8M0204722

• Supersedes 12-8M0027721 and earlier 12-86645 washer references

• Used between the impeller and driveshaft on compatible water pump assemblies

• Commonly used on Mercury / Mariner impeller applications up to 50HP where specified

  

🔄 Supersession & Cross Reference

  

OEM Supersession Chain:

  

• 12-8M0204722 → Supersedes 12-8M0027721

• 12-8M0027721 → Supersedes 12-86645

• 12-86645 earlier OEM impeller washer reference

• 12-86645-1 related formatted washer reference

  

OEM / Related Numbers:

  

• 12-8M0204722

• 8M0204722

• 128M0204722

• 12-8M0027721

• 8M0027721

• 12-86645

• 86645

• 12-86645-1

• 866451

  

Aftermarket / Verified Equivalents:

  

• Sierra: 18-2560

• Sierra: 18-2560-9

• GLM: 31210

• Mallory: 9-72009

• Chrysler / Force / US Marine: 12-866451

  

🚤 Compatibility

  

Commonly used on:

  

• Mercury / Mariner outboard water pump impeller assemblies

• Driveshaft / impeller washer positions in small to mid-range Mercury water pump housings

• Water pump repair work where the original 12-86645 / 12-8M0027721 washer has been replaced by 12-8M0204722

  

Typically suits:

  

• Engine models:

• Mercury / Mariner 9.9HP water pump applications where 12-86645 / 12-8M0204722 is specified

• Mercury / Mariner 15HP water pump applications where 12-86645 / 12-8M0204722 is specified

• Mercury / Mariner 20HP water pump applications where 12-86645 / 12-8M0204722 is specified

• Mercury / Mariner 25HP water pump applications where 12-86645 / 12-8M0204722 is specified

• Mercury / Mariner 30HP water pump applications where 12-86645 / 12-8M0204722 is specified

• Mercury / Mariner 40HP water pump applications where 12-86645 / 12-8M0204722 is specified

• Mercury / Mariner 50HP water pump applications where 12-86645 / 12-8M0204722 is specified

• Mercury / Mariner 9.9HP to 50HP 2-stroke impeller assemblies using the 47-850891 / 47-850893 / 47-8M0027792 / 47-8M0204712 impeller family

• Mercury / Mariner 40HP to 50HP 4-stroke water pump assemblies where the diagram specifies washer 12-8M0204722

  

• HP Range: commonly 9.9HP - 50HP where specified

• Engine Type: Mercury / Mariner outboard

• System Type: Water pump impeller / driveshaft washer

  

🔌 Function

  

The washer spaces and supports the impeller correctly on the driveshaft inside the water pump assembly. It helps maintain proper pump stack height and reduces incorrect contact between the impeller and surrounding water pump components.

  

Common signs of failure:

  

• Washer missing during impeller service

• Water pump stack assembled with incorrect spacing

• Impeller rubbing or premature wear

• Washer cracked, distorted or hardened

• Replacement required during water pump rebuild

  

📦 Condition

  

• Genuine Quicksilver part

• Brand new

• Supplied in original or equivalent packaging

## Details

- **Price:** 3.15 AUD
- **Vendor:** Quicksilver
- **Tags:** Quicksilver Marine Parts | Oils Service Kits & Engine Components

## Variants

| Variant | Price | Available |
|---------|-------|-----------|
| Default Title | 3.15 AUD | In stock |

## Images

- 128M0204722 Mercury MerCruiser 8M0204722 Washer | Genuine Quicksilver OEM Part

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> Source: [Sawley's Auto and Marine](www.sawleysautoandmarine.com.au/products/128m0204722-mercury-mercruiser-8m0204722-washer-genuine-quicksilver-oem-part)
> Updated: 2026-05-17