Sierra Seal 18-0558, 44mm ID x 7mm Width Marine Shaft Seal

The Sierra 18-0558 is a marine oil seal built to keep water and contaminants out while retaining lubrication in rotating shaft applications on inboard and sterndrive engines. It is engineered to meet the demands of high-horsepower marine engines and to hold up in the harsh marine environment, where constant exposure to saltwater, vibration, and heat cycling causes ordinary seals to fail prematurely. Sierra states that this seal meets or exceeds the performance of the original equipment part it replaces, making it a dependable choice when a shaft seal needs replacing during an engine rebuild, lower-unit service, or routine maintenance.

The seal has a machined exterior finish for a precise, consistent fit against its mating bore, and it is sized with a 44 mm inside diameter and a 7 mm width. Its compact size and light weight make it easy to install as part of a broader engine or drive service without adding measurable bulk to the assembly. Sierra supplies parts like this one to OEM engine manufacturers and boat builders, so the 18-0558 is manufactured to the same quality standard used in original production.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-0558
• Product Name: Seal
• Inside Diameter: 44 mm
• Width: 7 mm
• Exterior Finish: Machined
• Weight: 0.04 pounds
• UPC: 808282265427

Frequently Asked Questions

What are the dimensions of the Sierra 18-0558 seal? The Sierra 18-0558 seal has a 44 mm inside diameter and a 7 mm width.

How much does the 18-0558 seal weigh? It weighs 0.04 pounds, a lightweight component sized for shaft seal applications.

Is the Sierra 18-0558 an OEM-equivalent part? Yes, Sierra states this seal meets or exceeds the performance of the original equipment part it replaces.

What finish does the 18-0558 seal have? A machined exterior finish is used on the Sierra 18-0558 to ensure a precise, consistent fit in its mating bore.

What is included when I order part number 18-0558? The order includes one Sierra 18-0558 seal; no additional hardware or gaskets are bundled with it.

Can the 18-0558 seal be used in marine engine or drive service? Yes, it is designed for use as a shaft seal in marine engine and drive applications where water and contaminant exclusion is required.

Does Sierra manufacture the 18-0558 to OEM standards? Sierra supplies parts to OEM engine manufacturers and boat builders, and the 18-0558 seal is produced to that same quality standard.

Is the 18-0558 seal still in production? Yes, the Sierra 18-0558 seal is an active, currently produced part number.

How is the 18-0558 different from a generic aftermarket seal? The 18-0558 is manufactured by Sierra to meet or exceed the original equipment part's specifications, rather than being a generic universal-fit substitute.

What is the inside diameter of the 18-0558 shaft seal? The inside diameter of the Sierra 18-0558 is 44 mm, sized to seat around the shaft it seals.