Threlaco Outboard Motor Flusher and Gear Oil Pump Kit – Dual-Inlet 15.7" Flusher + Quart Bottle Adapters, Galvanized Steel

Threlaco’s two-piece kit pairs a dual-inlet outboard motor flusher with a lower unit gear oil pump so you can flush cooling passages and change gear oil from standard quart bottles with minimal fuss.

Keep your boat’s outboard running cleaner and more reliable with a compact maintenance combo that fits most marine engines. The kit combines a 15.7-inch external flusher featuring two water inlets and a lower-unit gear oil pump with multiple adapters so you can extract and supply gear oil from common quart bottles. Built with galvanized reinforced steel, spring steel, and an extruded rubber sleeve, the components are designed for repeated dockside use and straightforward setup.

How do I use the flusher to rinse my outboard after a day on the water?

Set the rectangular rubber sleeve over the engine’s water inlet, attach your garden hose to the kit’s 5/8" quick-connect, and run water through the dual inlets to circulate fresh water through the cooling passages. The dual-inlet design increases flow and coverage, helping dislodge salt, sand, and debris that can build up after use in saltwater or silty conditions.

• Slide the rubber sleeve onto the inlet and secure the cup cover.
• Connect a garden hose to the 5/8" quick-connect valve.
• Run water at normal household pressure until clear water exits the engine.
• Flush both inlets to maximize flow and remove deposits.

Can the lower unit gear oil pump handle different bottle sizes and gear cases?

The pump is built to work with common quart bottles using its included adapters and tubing, and it delivers roughly 8cc per pump stroke for controlled oil transfer. Three adapter sizes—3/8", 8mm, and 10mm—allow the pump to mate with a range of lower-unit fill/vent fittings and bottle necks for versatile gear service.

• Includes three adapters for different fitting sizes.
• Compatible with standard quart bottles using the supplied tubes.
• Galvanized reinforced steel pump body for durability.
• Approximately 8cc per pump stroke gives predictable flow.

What materials and build details make this set reliable for marine use?

Critical wear components use corrosion-resistant materials suited for a marine environment: the adapter is galvanized reinforced steel while the sleeve assembly combines spring steel with an extruded rubber overlay for a secure, flexible seal. The robust construction helps the kit withstand repeated exposure to wet conditions and provides a stable connection during flushing or oil changes.

• Lower unit adapter: galvanized reinforced steel for corrosion resistance.
• Rectangular sleeve: spring steel core with extruded rubber for a tight seal.
• Flusher length: about 15.7 inches (40 cm) for easy reach to inlet housings.
• External thread connector and sleeve sized for broad compatibility.

How simple is installation and what should I check before using the kit?

Installation is intentionally straightforward: place the cup cover and sleeve over the inlet, attach your hose to the quick-connect, or fit the pump adapters and tubing to your oil bottle and lower unit fittings. Before starting, confirm the adapter size matches your engine’s fittings and inspect seals for wear to avoid leaks during flushing or pumping.

• Measure inlet and lower-unit fittings prior to purchase for best fit.
• Ensure rubber sleeve sits snug to prevent splashing or loss of pressure.
• Use the appropriate adapter (3/8", 8mm, or 10mm) for oil service.
• Hand-tighten connections; avoid over-torquing plastic hose fittings.

Who this is for: Boaters and marine technicians who perform routine outboard maintenance—especially saltwater anglers, rental fleets, and weekend cruisers—will appreciate Threlaco’s compact flusher and pump set. It’s tailored for anyone who wants a portable, economical way to flush cooling systems and change lower unit gear oil using standard quart bottles, with durable materials and adapters to fit a wide range of outboard motors.