804149 Mercury Valve Plate | Genuine Used Part

🔧 Product Description

Genuine Mercury Cylinder Block Valve Plate - Part Number: 804149

A genuine Mercury valve plate fitted within the cylinder-block and crankcase assembly of selected Yamaha-manufactured 75HP to 115HP four-stroke outboards.

The plate closes and supports the associated internal valve passage. Its exact location and connected valve components vary by engine version, so installation should follow the applicable cylinder-block diagram.

⚙️ Key Features

• Genuine Mercury internal engine component
• Correct part number 804149
• Identified by Mercury as a valve plate
• Used on Yamaha-built Mercury inline-four engines
• Factory-machined sealing and mounting surfaces
• Discontinued or limited-service OEM component

🚤 Compatibility

Documented on

• Mercury 75HP carburetted four-stroke, serial 0G960500-0T800999
• Mercury 75HP carburetted four-stroke, serial 0T801000-1B226999
• Mercury 75HP EFI four-stroke, serial 1B172291-1B366822
• Mercury 80HP EFI four-stroke, serial 1B227000-1B366822
• Mercury 90HP carburetted four-stroke, serial 0G960500-1B226999
• Mercury 90HP EFI four-stroke, serial 1B172291-1B366822
• Mercury 100HP EFI four-stroke, serial 1B227000-1B366822
• Mercury 115HP EFI four-stroke, serial 0T178500-1B366822
• Engine Type: Yamaha-manufactured Mercury inline-four four-stroke outboard
• Fitment Requirement: Confirm the cylinder-block diagram and plate location

🔌 Function

The plate forms part of an internal valve passage in the cylinder-block or crankcase assembly. It supports correct one-way or pressure-controlled flow through that passage and provides a sealed service surface.

⚠️ Common Signs of Failure

• Plate is warped or corroded
• Internal passage does not seal correctly
• Gasket leaks oil, vapour or cooling fluid
• Mounting threads are damaged
• Deposits restrict the associated valve passage

🔄 Supersession & Cross Reference

OEM Supersession Chain

• 804149 current documented valve-plate reference
• No direct supersession confirmed

OEM / Related Numbers

• 804149
• Related cylinder-block valve components
• Related plate gasket, screws and retainers
• Related Yamaha-manufactured crankcase assembly

Aftermarket / Verified Equivalents

• Specialist used or new-old-stock Mercury 804149 valve plate
• Used complete cylinder-block valve assembly
• No verified direct Yamaha part-number cross-reference
• No verified direct aftermarket plate

📦 Condition

• Genuine used part
• Removed from running engine where applicable
• In good working condition unless otherwise stated
• Replace the associated gasket before installation