Sierra 18-0578 One-Piece Rear Main Seal / Timing Cover Seal, Replaces 26-67388

The Sierra 18-0578 is a one-piece rear main seal and timing cover seal built for marine engine crankshaft sealing applications. Its one-piece construction combines the rear main seal and timing cover seal function into a single component, simplifying installation compared to multi-piece seal designs and reducing the number of separate parts a technician needs to fit and align during an engine rebuild or reseal job. The seal has a white finish and a compact, low-profile design measuring 5.6 x 3.7 x 0.6 inches, with a light overall weight of 0.12 pounds that keeps it easy to handle during service work.

This seal directly replaces OEM part number 26-67388, making it a straightforward drop-in option when the original equipment seal needs replacement. Each Sierra seal is built to meet or exceed the specifications of the original equipment part it replaces, giving boat owners and marine technicians a reliable aftermarket alternative for crankshaft sealing repairs. It is engineered specifically for Mercruiser crankshaft sealing applications, and is sold as a single unit.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-0578
• Category: Rear Main Seal / Timing Cover Seal
• Design: One-Piece
• Color: White
• Application: Marine Engine Crankshaft Sealing
• Country of Origin: China
• Dimensions: 5.6 x 3.7 x 0.6 inches
• Weight: 0.12 pounds
• UPC: 030999973993
• GTIN: 00030999973993
• OEM Cross Reference: 26-67388
• Unit Count: 1
• Warranty: Limited Warranty

Fitment

Engineered for Mercruiser crankshaft sealing applications as a one-piece rear main seal and timing cover seal.

Replaces (OEM)

• 26-67388

Frequently Asked Questions

What OEM part number does the Sierra 18-0578 replace? The Sierra 18-0578 replaces OEM part number 26-67388, so it is a direct fit wherever that original seal was used.

Is the Sierra 18-0578 a one-piece or two-piece seal? It is a one-piece design that combines the rear main seal and timing cover seal into a single component, which simplifies installation versus a multi-piece seal.

What color is the Sierra 18-0578 seal? It has a white finish.

How big is the Sierra 18-0578 seal? The Sierra 18-0578 measures 5.6 x 3.7 x 0.6 inches.

How much does the Sierra 18-0578 weigh? 0.12 pounds, making it easy to handle during installation.

Where is the Sierra 18-0578 manufactured? The country of origin listed for the Sierra 18-0578 is China.

Does the Sierra 18-0578 meet OEM specifications? Yes, the Sierra 18-0578 is built to meet or exceed the specifications of the original equipment seal it replaces, OEM 26-67388.

What is included when you order the Sierra 18-0578? One Sierra 18-0578 one-piece rear main seal and timing cover seal (unit count of 1).

What is the UPC for the Sierra 18-0578? The UPC is 030999973993.

What application is the Sierra 18-0578 designed for? The 18-0578 is engineered for Mercruiser crankshaft sealing applications as a rear main seal and timing cover seal.

Is the Sierra 18-0578 covered by a warranty? Yes, the Sierra 18-0578 carries a limited warranty.