Sierra 18-3013 Upper Water Pump Seal, Replaces 26-821309, Fits 25/30/40/45/50 HP 4-Stroke Outboards

The Sierra 18-3013 is an upper water pump seal used to restore a tight, factory-spec seal in the water pump housing of covered outboard engines. As the pump wears, this upper seal is one of the first components to lose its sealing ability, allowing cooling water to bypass the pump and reducing water flow to the engine. Replacing it as part of a water pump rebuild helps maintain proper cooling water pressure and delivery.

Part 18-3013 is a direct equivalent to OEM number 26-821309 and is designed specifically for 4-stroke outboards rated 25, 30, 40, 45, and 50 HP with serial number OG760300 and up. Because fitment is tied to that serial number range, confirm your engine's serial number before ordering to make sure this is the correct seal for your unit. At 0.02 pounds, it is a small, lightweight component intended to be installed alongside the other water pump wear parts (impeller, gaskets, and housing) during a routine pump rebuild.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-3013
• Product Type: Upper Water Pump Seal
• OEM Cross Reference: 26-821309
• Fitment: 4-Stroke Outboards, 25/30/40/45/50 HP, serial number OG760300 and up
• Weight: 0.02 pounds
• UPC: 808282112851

Fitment

• 4-Stroke Outboards, 25/30/40/45/50 HP, serial number OG760300 and up

Replaces (OEM)

• 26-821309

Frequently Asked Questions

What OEM part number does the Sierra 18-3013 seal replace? It replaces OEM number 26-821309. The Sierra 18-3013 upper water pump seal is a direct equivalent, so you can order it using either number.

Which outboard engines fit the 18-3013 upper water pump seal? This seal is designed for 4-stroke outboards rated 25, 30, 40, 45, and 50 HP with serial number OG760300 and up.

Does the engine serial number matter when ordering this seal? Yes. The Sierra 18-3013 is fitted specifically to 4-stroke outboards with serial number OG760300 and up, so confirming your engine's serial number before ordering ensures correct fitment.

How much does the Sierra 18-3013 seal weigh? It weighs 0.02 pounds, making it a lightweight component of a water pump rebuild kit or standalone repair.

Is the 18-3013 a genuine Sierra part or aftermarket? The 18-3013 is a Sierra-branded upper water pump seal, sold under Sierra's own part number and manufactured to their specification.

What does the upper water pump seal actually do? In the water pump assembly, this seal keeps cooling water contained within the pump housing so it is delivered to the engine rather than leaking past worn components; the Sierra 18-3013 replaces this seal when it wears out.

Will the 18-3013 fit outboards outside the 25-50 HP range? Fitment for the Sierra 18-3013 is specified for 25, 30, 40, 45, and 50 HP 4-stroke outboards with serial number OG760300 and up; it is not listed for other horsepower ratings.

What is included when you order part 18-3013? Ordering Sierra part 18-3013 gets you a single upper water pump seal.

Is there more than one cross-reference number for this seal? No, the Sierra 18-3013 upper water pump seal has one listed OEM cross-reference: 26-821309.

What is the UPC for the Sierra 18-3013 seal? The UPC for the Sierra 18-3013 upper water pump seal is 808282112851.