Sea-Dog Inboard Motor Flush 521550-1 - Molded Rubber and Aluminum Lower Unit Flusher

The Sea-Dog Inboard Motor Flush (521550-1) is a molded rubber and aluminum flushing tool designed to clear salt, sand, minerals, and other contaminants out of an inboard engine's lower unit cooling system. Regular flushing with fresh water helps extend the service life of the engine by preventing buildup inside the cooling passages.

The design uses a rubber cup that fits directly over the water intake, sealing against the hull, while an extending aluminum leg holds the cup firmly in place. A standard garden hose connects to the flusher to supply fresh water directly to the intake, and no tools are required for setup or use. This makes it a practical, low-effort way to flush an inboard engine while it is out of the water.

It is well suited to routine maintenance tasks such as winterizing, spring commissioning, and general tune-ups where running the engine with a fresh water supply is needed. The molded rubber and aluminum construction is built to hold a seal against the hull while withstanding repeated hose connections.

Specifications

• Brand: Sea-Dog
• Manufacturer Part Number: 521550-1
• Material: Molded Rubber/Aluminum
• Dimension A: 15-1/2 inches
• Dimension B: 27-1/2 inches
• Weight:.99 pounds
• Standard Pack: 1 each
• Mounting Type: Flush
• Recommended Use: For salt water
• UPC: 035514521451

Replaces (OEM)

• 5215501

Frequently Asked Questions

What does the Sea-Dog 521550-1 Inboard Motor Flush do? It flushes salt, sand, minerals, and other contaminants out of an inboard engine's lower unit cooling system using fresh water, which helps extend the engine's service life.

How do I use this motor flush? Fit the rubber cup of the 521550-1 over the water intake, connect a garden hose to it, and extend the aluminum leg to seal the cup against the hull; no tools are required.

Do I need any tools to install or use it? No tools are required. The Sea-Dog 521550-1 seats the rubber cup over the intake and the aluminum leg extends to hold the seal against the hull.

What is the 521550-1 made of? It is constructed of molded rubber and aluminum, combining a rubber sealing cup with an aluminum extending leg.

What are the dimensions of this motor flush? The Sea-Dog Inboard Motor Flush measures 15-1/2 inches (A) by 27-1/2 inches (B).

How much does the 521550-1 weigh? The Sea-Dog Inboard Motor Flush weighs.99 pounds.

Is this connected to a standard garden hose? Yes, the 521550-1 connects to a garden hose to supply fresh water through the cup and into the engine's cooling system.

When should I use an inboard motor flush like this? It is intended for winterizing, tune-ups, and other maintenance that requires running an inboard engine while it is out of the water.

Is the Sea-Dog 521550-1 suitable for saltwater use? Yes, the 521550-1 is recommended for use with engines operated in salt water, helping remove salt deposits from the cooling system.

Does this product have an OEM equivalent part number? Yes, the Sea-Dog 521550-1 Inboard Motor Flush has an OEM equivalent part number of 5215501.

How many units come in a pack? The Sea-Dog 521550-1 Inboard Motor Flush is sold in a standard pack of 1 each.

Does the mounting design work on any hull? The rubber cup seals against the hull around the water intake while the aluminum leg extends to hold it in place, a flush-mount design rather than a fixed hardware installation.