Mercury 15 EFI FourStroke, Service Manual

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1. Position a clean drain pan under the gear housing and remove the fill and vent screws with gaskets from the gear housing.
a - Vent screw
b - Fill screw
2. Inspect the gear lubricant for metal particles. Presence of a small amount of fine metal particles resembling powder
indicates normal wear. Presence of larger particles or a large quantity of fine particles indicates a need for gear housing
disassembly and component inspection.
3. Note the color of the gear lubricant. White or cream color indicates the presence of water in the lubricant. Check the drain
pan for water separation from the lubricant. Presence of water in the gear lubricant indicates the need for disassembly and
inspection of oil seals, seal surfaces, O‑rings, and gear housing components. Pressure check the gearcase prior to
disassembly.
NOTE: When draining the gearcase for the first time, lubricant may appear cream colored due to the mixing of assembly
lubricant and gear lubricant. This is not an indication of water intrusion. If, during subsequent draining of the gearcase,
lubricant appears cream colored or milky, water may be present. The gearcase should be disassembled and all gaskets,
seals, and O‑rings replaced. Inspect all components for water damage.
NOTE: Gear lubricant drained from a recently run gearcase will be a light chocolate brown in color due to agitation/
aeration. Oil that is stabilized will be a clear yellow brown in color.
Gearcase Lubricant Capacity
Approximately 460 ml (15.6 fl oz).
Gearcase Lubricant Recommendation
Mercury or Quicksilver Premium or High Performance Gear Lubricant.
Filling the Gearcase
1. Place the outboard in a vertical operating position or in the full tilt position.
2. Remove the vent plug from the vent hole.
3. Place the lubricant tube into the fill hole and add lubricant until it appears at the vent hole.
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IMPORTANT: Replace the sealing washers with new sealing washers.
4. Stop adding lubricant. Install the vent plug and sealing washer before removing the lubricant tube.
a
b
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Maintenance
90-8M0125265 eng NOVEMBER 2017 © 2018 Mercury Marine Page 1B-15