Sierra 18-0515 Oil Seal, Replaces Mercury 26-30530, for Outboard Powerhead Crankshaft

The Sierra 18-0515 is a round oil seal designed for Mercury outboard powerhead crankshaft applications. It seals the crankshaft bore to keep lubricating oil contained within the powerhead while preventing water and contaminants from entering, protecting internal engine components from leaks and premature wear. The seal is finished in white and is built to Sierra's standard fit and function for this position.

This seal carries precise dimensions of 0.540 inch shaft size, 1.004 inch outside diameter, and 0.303 inch width, matching the profile of the Mercury OEM oil seal it replaces. Because oil seals in this size range are used across multiple engine positions, always confirm these three measurements against your old seal or your engine's parts diagram before ordering to ensure a correct fit.

Sierra International supplies replacement parts for marine engines, and the 18-0515 is cataloged specifically as a Mercury outboard powerhead crankshaft seal, making it a straightforward like-for-like replacement for the corresponding Mercury OEM part. It is sold as a single seal.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-0515
• OEM Cross Reference: 26-30530
• Shaft Size: 0.540 inches
• Outside Diameter: 1.004 inches
• Width: 0.303 inches
• Shape: Round
• Color: White
• Weight: 0.01 pounds
• UPC: 030999874276
• Application: Mercury outboard powerhead crankshaft seal

Fitment

Designed for Mercury outboard powerhead crankshaft applications requiring an oil seal with a 0.540 inch shaft size, 1.004 inch outside diameter, and 0.303 inch width. Verify these dimensions against your existing seal before purchase.

Replaces (OEM)

• 26-30530

Frequently Asked Questions

What does the Sierra 18-0515 oil seal fit? The Sierra 18-0515 is cataloged for Mercury outboard powerhead crankshaft applications, sealing the crankshaft bore to retain lubricating oil and keep out contaminants.

Is the Sierra 18-0515 the same as Mercury 26-30530? Yes, the 18-0515 is Sierra's direct replacement for Mercury OEM oil seal 26-30530, matching its shaft size, outside diameter, and width.

What are the dimensions of the 18-0515 oil seal? This seal measures 0.540 inches at the shaft, 1.004 inches on the outside diameter, and 0.303 inches wide.

What color is the Sierra 18-0515 oil seal? It is white, as manufactured by Sierra International.

How much does the 18-0515 oil seal weigh? The Sierra 18-0515 weighs 0.01 pounds.

How do I know if this seal will fit my engine? Compare the shaft size, outside diameter, and width of your existing seal to the 18-0515 specs of 0.540 inches, 1.004 inches, and 0.303 inches respectively, since seals in this size range can be used in more than one engine position.

Is the Sierra 18-0515 a genuine Mercury part or aftermarket? The 18-0515 is a Sierra-manufactured aftermarket seal built to replace Mercury OEM part 26-30530, not a genuine Mercury-branded component.

What shape is the 18-0515 seal? The Sierra 18-0515 oil seal is round in shape.

What comes in the package with the 18-0515? The package includes one Sierra 18-0515 oil seal.

What is the UPC for the Sierra 18-0515 oil seal? The UPC for this Sierra oil seal is 030999874276.

What category of part is the 18-0515? The 18-0515 is classified as a Mercury outboard powerhead crankshaft seal.