19-865866 Mercury MerCruiser Seal | Genuine Quicksilver OEM Part

🔧 Product Description

Genuine Quicksilver Bravo Shift Shaft Oil Seal Plug - Part Number: 19-865866

A genuine Quicksilver shift-cavity seal plug for selected Mercury MerCruiser Bravo sterndrive housings.

The formed plug fits into the designated shift-shaft oil passage in the revised Bravo housing design. It forms part of the drive sealing system, helping retain gear lubricant and prevent water entering through the shift-shaft cavity.

Mercury introduced this plug-style arrangement from Bravo drive serial number 0W258350, replacing the earlier O-ring-style sealing arrangement used in preceding housings.

⚙️ Key Features

• Genuine Quicksilver OEM shift-cavity seal plug
• Correct Mercury part number 19-865866
• Used in revised Bravo shift-shaft housing assemblies
• Plug-style design introduced from drive serial 0W258350
• Helps retain gear lubricant and prevent water intrusion

🚤 Compatibility

Commonly used on

• Mercury MerCruiser Bravo sterndrive shift-shaft cavities
• Revised plug-style Bravo driveshaft housing assemblies
• Standard, X-series and XR performance drives where the housing diagram specifies 19-865866

Typically suits

• Drive models:
• MerCruiser Bravo One
• MerCruiser Bravo Two
• MerCruiser Bravo Three
• MerCruiser Bravo X One
• MerCruiser Bravo X Two
• MerCruiser Bravo X Three
• MerCruiser Bravo XR One
• MerCruiser Bravo XR Three
• MerCruiser Bravo XR SportMaster
• Mercury Racing Bravo XR Sport applications
• Integrated transom and high-performance Bravo assemblies using the revised shift-cavity plug
• Bravo One catalogue families beginning at serial 0W250000 where the later housing diagram specifies 19-865866
• Bravo Two catalogue families beginning at serial 0W250000 where the later housing diagram specifies 19-865866
• Bravo XR catalogue families beginning at serial 0W240000 where the later housing diagram specifies 19-865866
• Revised plug-style Bravo housing applications from serial 0W258350
• Drive Type: MerCruiser Bravo One, Bravo Two, Bravo Three, Bravo X and Bravo XR
• Serial Range: Revised seal-plug design introduced from 0W258350
• System Type: Shift-shaft cavity and driveshaft housing sealing system
• Year Range: Serial-number controlled; revised plug-style design introduced during 2006 production

🔌 Function

The seal plug closes the designated shift-shaft oil passage in the Bravo drive housing. It helps retain sterndrive gear lubricant, prevent water entry and maintain the housing's ability to pass pressure and vacuum testing.

⚠️ Common Signs of Failure

• Gear lubricant around the shift-shaft cavity
• Unexplained drop in drive-lubricant reservoir level
• Water-contaminated or milky gear lubricant
• Sterndrive fails pressure or vacuum testing
• Seal plug damaged, loose, deteriorated or missing

🔄 Supersession & Cross Reference

OEM Supersession Chain

• 19-865866 current plug-style shift-cavity seal reference
• 25-62705 earlier O-ring sealing arrangement used before drive serial 0W258350

OEM / Related Numbers

• 19-865866
• 865866
• 19865866
• 25-62705 earlier shift-cavity O-ring
• 62705
• 23-861209A1 related shift-shaft bushing kit
• 26-127091 related shift-shaft seal
• 806552A1 related shift yoke and cam assembly
• 745061655249

Aftermarket / Verified Equivalents

• No aftermarket equivalent

📦 Condition

• Genuine Quicksilver part
• Brand new
• Supplied in original or equivalent packaging