804085 Mercury Cover | Genuine Used Part

🔧 Product Description

Genuine Mercury Cylinder Head Water-Jacket Anode Cover - Part Number: 804085

A genuine used Mercury cylinder-head cooling-passage cover for Yamaha-built 75HP, 80HP, 90HP, 100HP and 115HP four-stroke outboards.

The cover closes an internal water-jacket opening and carries the sacrificial corrosion-protection anode used inside the cylinder-head cooling circuit. Mercury replaced the original loose cover reference with complete cover kit 804085A01.

⚙️ Key Features

• Genuine Mercury cylinder-head water-jacket cover
• Correct original part number 804085
• Current service replacement is cover and anode kit 804085A01
• Used on Yamaha-built Mercury and Mariner four-stroke engines
• Protects and seals an internal cooling-water and sacrificial-anode chamber

🚤 Compatibility

Commonly used on

• Mercury and Mariner Yamaha-built four-stroke cylinder heads
• Internal water-jacket and sacrificial-anode cover locations
• Carburetted and EFI 75HP to 115HP four-stroke outboards

Typically suits

• Engine models:
• Mercury / Mariner 75HP four-stroke - serial 0G960500 to 0T800999
• Mercury / Mariner 75HP four-stroke - serial 0T801000 to 1B226999
• Mercury / Mariner 80HP EFI four-stroke applications using cover 804085
• Mercury / Mariner 90HP four-stroke - serial 0G960500 to 0T800999
• Mercury / Mariner 90HP four-stroke - serial 0T801000 to 1B226999
• Mercury / Mariner 100HP EFI four-stroke applications using cover 804085
• Mercury / Mariner 115HP EFI four-stroke - serial 0T178500 to 0T800999
• Mercury / Mariner 115HP EFI four-stroke - serial 0T801000 to 1B226999
• Mercury / Mariner 115HP EFI four-stroke - serial 1B227000 to 1B366822
• Corresponding Yamaha-built 75HP, 80HP, 90HP, 100HP and 115HP four-stroke powerheads using the same cover-and-anode arrangement
• HP Range: 75HP - 115HP
• Engine Type: Mercury / Mariner EFI and carburetted inline 4-cylinder four-stroke outboard
• Year Range: Approximately late 1990s - 2006

🔌 Function

The cover seals a cylinder-head cooling-water passage and holds the internal sacrificial anode. The anode corrodes preferentially to help protect the aluminium cylinder head and water jacket from galvanic attack.

⚠️ Common Signs of Failure

• Water leakage or salt staining around the cover
• Cover heavily corroded or pitted internally
• Sacrificial anode fully consumed
• Gasket surface distorted or damaged
• Mounting bolts seize, break or strip in the cylinder head

🔄 Supersession & Cross Reference

OEM Supersession Chain

• 804085A01 → Supersedes 804085
• 804085 original Mercury cover reference

OEM / Related Numbers

• 804085A01
• 804085
• 97-804085A01 - Complete anode-holder kit reference
• 25-804086 - Related grommet
• 10-827207 - Related mounting bolt
• 27-8041151 - Related gasket
• 23-804116 / 23-8M0070515 - Related collar
• 804118T2 - Related early cover kit
• 881313T1 - Related later cover kit

Aftermarket / Verified Equivalents

• DAM Marine: 97-804085A01 Complete Anode Holder Kit
• Yamaha / Mercury aftermarket complete anode-cover kit replacing 804085A01
• Direct-replacement cover and anode assembly referencing Mercury 804085 / 804085A01

📦 Condition

• Genuine used part
• Removed from running engine where applicable
• In good working condition unless otherwise stated