Sierra Tilt/Trim Reservoir 18-6778, Replaces 883166A1, 883166A2, for Motors with 4 Screw Attachments

The Sierra 18-6778 Tilt/Trim Reservoir is a top mount reservoir designed for Oildyne power trim pumps with plastic reservoirs and tilt/trim motors that use a 4 screw attachment mounting pattern. It serves as the fluid reservoir for the outboard or sterndrive power trim system, holding the hydraulic fluid that the trim pump circulates to raise and lower the drive unit. The reservoir is constructed of plastic with a machined exterior finish for a consistent fit against the trim motor housing.

This reservoir directly replaces 883166A1 and 883166A2, making it a straightforward swap for boat owners dealing with a cracked, leaking, or worn original reservoir. Because it is built to the 4 screw attachment configuration, it is intended for trim motors that use that specific mounting style rather than universal fitment across all trim systems. Sierra manufactures this part to meet or exceed the performance of the original equipment it replaces, and it is backed by Sierra's standard customer satisfaction warranty. Boat owners performing trim system maintenance or troubleshooting fluid loss in the power trim unit can use this reservoir as a direct component-level repair rather than replacing the entire trim motor assembly.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-6778
• Product Type: Tilt/Trim Reservoir
• Mount Type: Top mount reservoir
• For Use With: Oildyne power trim pumps with plastic reservoir and tilt/trim motors with 4 screw attachments
• Material: Plastic
• Exterior Finish: Machined
• Item Dimensions: 7 x 6 x 6 inches
• Weight: 0.78 pounds
• Fuel Type Compatibility: Diesel, Gasoline
• UPC: 808282100506

Fitment

• Motors with 4 screw attachments
• Oildyne power trim pumps with plastic reservoir

Replaces (OEM)

• 883166A1
• 883166A2

Frequently Asked Questions

What does the Sierra 18-6778 tilt/trim reservoir fit? The Sierra 18-6778 fits motors with 4 screw attachments and is designed for Oildyne power trim pumps that use a plastic reservoir.

What OEM part numbers does 18-6778 replace? This reservoir directly replaces OEM part numbers 883166A1 and 883166A2.

Is the 18-6778 reservoir a genuine OEM part or aftermarket? The 18-6778 is a Sierra-manufactured aftermarket reservoir built to meet or exceed the performance of the original equipment part it replaces.

What material is the Sierra 18-6778 tilt/trim reservoir made of? It is made of plastic with a machined exterior finish.

What are the dimensions of the 18-6778 reservoir? The Sierra 18-6778 measures 7 x 6 x 6 inches.

How much does the Sierra 18-6778 tilt/trim reservoir weigh? The 18-6778 reservoir weighs 0.78 pounds.

Does the 18-6778 come with mounting hardware? The listing for 18-6778 covers the tilt/trim reservoir itself; check the mounting hardware on your existing trim motor when installing it, since the reservoir is designed for motors with a 4 screw attachment pattern.

Will the 18-6778 reservoir work with a bottom mount trim system? No, the 18-6778 is a top mount reservoir, so it is intended for trim motors that use a top mount configuration with 4 screw attachments.

Is the Sierra 18-6778 reservoir covered by a warranty? Yes, the 18-6778 is covered under Sierra's customer satisfaction warranty as part of the Sierra parts line.

What fuel types is the 18-6778 reservoir compatible with? The 18-6778 is compatible with boats running either diesel or gasoline power trim systems.

Why would I need to replace the tilt/trim reservoir on my boat? A cracked, leaking, or degraded reservoir like the original 883166A1 or 883166A2 can cause trim fluid loss and inconsistent trim operation, and the Sierra 18-6778 provides a direct replacement for that reservoir.

Does the Sierra 18-6778 include the tilt/trim motor as well? No, the 18-6778 is the reservoir component only, for motors with 4 screw attachments; it does not include a motor assembly.