Sierra 18-1211 Two-Piece Rear Main Seal for 3.8L Marine Engines

The Sierra 18-1211 is a two-piece rear main crankshaft seal designed to seal the rear of the crankshaft where it exits the engine block on applicable marine engines. It is built to meet or exceed the fit, form, and function of the original equipment seal it replaces, giving boat owners a dependable option when rebuilding an engine or addressing a rear main oil leak. The two-piece construction allows the seal to be installed around the crankshaft without full engine disassembly in many rebuild situations, which is a common design advantage over full-circle, one-piece seals that require the crankshaft to be pulled.

This seal is used on 3.8L marine engines, where it is paired with a separate oil pan gasket during a rear main seal service. It also cross-references to a wide range of OMC, Evinrude/Johnson, Mercruiser, GLM, and Mallory rear main seal part numbers, making it a straightforward replacement for engines originally fitted with those components. As with all rear main seal jobs, a proper installation is important to prevent oil leaks at the rear of the crankcase, and the corresponding rear main crankshaft seal housing or block surface should be clean and free of damage before installation.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-1211
• Part Type: Rear Main Seal
• Design: Two-Piece
• Auto Part Position: Rear
• Included Components: Rear Main Seal
• Quantity: 1
• Weight: 0.07 pounds

Fitment

• 3.8L marine engine models

Replaces (OEM)

• GLM 85490
• Evinrude/Johnson 473423
• Mallory 9-61620
• Mercruiser FI5110041
• Mercruiser FI5110027
• Mercruiser FI5110026
• Mercruiser 26-49947
• Mercruiser 26-58203
• Mercruiser 26-814622
• OMC 473424

Frequently Asked Questions

What engines does the Sierra 18-1211 rear main seal fit? The Sierra 18-1211 is designed for 3.8L marine engine models.

Is the 18-1211 a one-piece or two-piece seal? It is a two-piece rear main seal, which allows installation around the crankshaft without requiring full engine disassembly in many rebuild scenarios.

What OEM part numbers does the Sierra 18-1211 replace? This seal cross-references to GLM 85490, Evinrude/Johnson 473423, Mallory 9-61620, Mercruiser FI5110041, FI5110027, FI5110026, 26-49947, 26-58203, and 26-814622, and OMC 473424.

Do I need any other gaskets when installing the 18-1211? On 3.8L models, the 18-1211 rear crank seal is used along with a separate oil pan gasket, part number 18-0362.

How much does the Sierra 18-1211 rear main seal weigh? The Sierra 18-1211 weighs 0.07 pounds.

Is the Sierra 18-1211 a genuine Sierra part or aftermarket equivalent? The 18-1211 is a Sierra-brand rear main seal manufactured to meet or exceed the original equipment part it replaces.

What comes included with part number 18-1211? The package includes one rear main seal, sold as a single unit (quantity 1).

Where is this seal located on the engine? The Sierra 18-1211 is installed at the rear position of the crankshaft, sealing the point where the crankshaft exits the rear of the engine block.

Can the Sierra 18-1211 replace a Mercruiser rear main seal? Yes, the 18-1211 cross-references to several Mercruiser part numbers, including FI5110041, FI5110027, FI5110026, 26-49947, 26-58203, and 26-814622.

Does the Sierra 18-1211 fit OMC or Evinrude/Johnson engines? It cross-references to OMC 473424 and Evinrude/Johnson 473423, so it fits engines that originally used those rear main seals.