Sierra 18-4258 Pipe Plug, 3/4 Inch Thread, Steel, Replaces Mercruiser 22-33198A1

The Sierra 18-4258 is a steel pipe plug with a 3/4 inch thread, built to seal unused ports on marine exhaust manifolds and related engine components. It is designed for use with the Sierra 18-1949 manifold spacer and is a common replacement item for boat owners servicing exhaust manifold assemblies. The plug is machined from steel and finished in silver, matching the quality and dimensions of the original equipment part it replaces. Because it threads directly into standard 3/4 inch NPT-style ports, it is a straightforward swap during manifold service, riser replacement, or general maintenance work where a factory pipe plug has corroded, stripped, or gone missing.

Sierra manufactures this plug to meet or exceed original equipment specifications, so fit, thread engagement, and sealing performance match what the factory part delivers. It is sold as a single item (one plug) and ships with the UPC 030999875709 for easy identification at checkout or in parts lookup systems.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-4258
• Thread Size: 3/4 inch
• Material: Steel
• Color: Silver
• Weight: 0.1 pounds
• UPC: 030999875709
• Compatible Manifold Spacer: 18-1949
• Number of Items: 1

Fitment

• Designed for use with the Sierra 18-1949 manifold spacer.

Replaces (OEM)

• Crusader 113186
• GLM 21892
• Mallory 9-41205
• Mercruiser 22-33198A1
• Mercruiser 22-41622
• Mercruiser 22-46754
• Mercruiser 22-33198
• Osco 1016012

Frequently Asked Questions

What thread size does the Sierra 18-4258 pipe plug have? The Sierra 18-4258 pipe plug has a 3/4 inch thread.

Is the Sierra 18-4258 a genuine Sierra part or an aftermarket copy? The 18-4258 is a genuine Sierra part, manufactured by Sierra to meet or exceed the original equipment specifications of the parts it replaces.

What OEM numbers does the Sierra 18-4258 pipe plug cross-reference to? It is interchangeable with Crusader 113186, GLM 21892, Mallory 9-41205, Mercruiser 22-33198A1, 22-41622, 22-46754, and 22-33198, as well as Osco 1016012.

What is the Sierra 18-4258 made of? Steel is the material used for the Sierra 18-4258 pipe plug, finished in silver.

How much does the 18-4258 pipe plug weigh? The Sierra 18-4258 pipe plug weighs 0.1 pounds.

What other part is the 18-4258 used with? The 18-4258 pipe plug is designed for use with the Sierra 18-1949 manifold spacer.

How many plugs come in one order of the 18-4258? One order of the Sierra 18-4258 includes a single pipe plug (quantity of 1).

Does the Sierra 18-4258 replace a Mercruiser pipe plug? Yes, the Sierra 18-4258 replaces Mercruiser pipe plugs 22-33198A1, 22-41622, 22-46754, and 22-33198.

What is the UPC for the Sierra 18-4258 pipe plug? The UPC for the Sierra 18-4258 pipe plug is 030999875709.

Can the Sierra 18-4258 be used to replace a Mallory pipe plug? Yes, the Sierra 18-4258 is interchangeable with Mallory part number 9-41205.