878587A1 Mercury Bottom Cowling (Port) | Genuine Used Part

🔧 Product Description

Genuine Mercury Port Lower Cowling Assembly - Part Number: 878587A1

A genuine Mercury and Mariner port-side lower engine cowling for selected 75HP to 115HP four-stroke outboards.

The cover forms the port half of the lower cowling beneath the removable top cover. It protects the lower powerhead, wiring, fuel-system components and engine rigging while joining the matching starboard cover to complete the lower engine enclosure.

Part number 878587A1 has been replaced by current Mercury lower-cowling reference 8M0107315.

⚙️ Key Features

• Genuine Mercury / Mariner port lower cowling
• Correct original part number 878587A1
• Superseded by current Mercury part number 8M0107315
• Used on selected Yamaha-based Mercury four-stroke outboards
• Matches the corresponding starboard lower-cowling assembly

🚤 Compatibility

Commonly used on

• Mercury and Mariner Yamaha-based four-stroke lower-cowling assemblies
• Port-side engine-pan applications using split lower covers

Typically suits

• Engine models:
• Mercury / Mariner 75HP FourStroke - serial 0G960500 to 0T800999
• Mercury / Mariner 75HP FourStroke - serial 0T801000 to 1B226999
• Mercury 80HP EFI FourStroke - serial 1B227000 to 1B366822
• Mercury / Mariner 90HP FourStroke - serial 0G960500 to 0T800999
• Mercury / Mariner 90HP FourStroke - serial 0T801000 to 1B226999
• Mercury 100HP EFI FourStroke - serial 1B227000 to 1B366822
• Mercury / Mariner 115HP EFI FourStroke - serial 0T178500 to 0T800999
• Mercury / Mariner 115HP EFI FourStroke - serial 0T801000 to 1B226999
• Mercury / Mariner 115HP EFI FourStroke - serial 1B227000 to 1B366822
• HP Range: 75HP - 115HP
• Engine Type: Mercury / Mariner inline four-cylinder EFI four-stroke outboard
• Year Range: Approximately 2000 - 2006

🔌 Function

The port lower cowling encloses the port side of the lower powerhead and provides the mounting and sealing surfaces required for the complete engine-cover assembly.

⚠️ Common Signs of Failure

• Cracks around mounting screws or latch points
• Broken mating edge between the lower covers
• Distortion prevents the top cowling from sealing correctly
• Damaged seal channel allows water into the engine compartment
• Missing mounting points cause vibration or movement

🔄 Supersession & Cross Reference

OEM Supersession Chain

• 8M0107315 → Supersedes 878587A1
• 878587A1 earlier Mercury port lower-cowling reference

OEM / Related Numbers

• 8M0107315
• 878587A1
• 878587
• 8M0113913 matching current starboard lower cowling
• 858743A2 earlier starboard lower cowling
• 8M0039078 related lower-cowling grommet
• 859251 earlier grommet reference
• 8M0109217 related lower-cowling seal
• 8253181 earlier lower-cowling seal reference

Aftermarket / Verified Equivalents

• No aftermarket equivalent

📦 Condition

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