Sierra 18-3742-9 Cotter Pin, OEM 314502 Replacement, Pack of 10

The Sierra 18-3742-9 Cotter Pin is a marine-grade fastener used to secure propeller nuts and other threaded hardware on outboard and stern drive lower units. Sold in a pack of 10, this pin is built to meet or exceed original equipment quality, making it a reliable choice for routine prop maintenance and hardware replacement. Each pin measures 1/8 x 1-1/4 inches and is constructed from alloy steel for corrosion resistance and durability in a marine environment.

This cotter pin is commonly paired with a prop nut and prop spacer during propeller installation, locking the nut in place to prevent it from backing off under vibration and load. It cross-references directly to OMC and Evinrude/Johnson part number 314502, so it is a straightforward replacement when servicing older Evinrude and OMC lower units. Keeping a pack on hand is useful for any boat owner who regularly removes and reinstalls a propeller, since cotter pins are a single-use fastener that should be replaced each time.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-3742-9
• Size: 1/8 x 1-1/4 inches
• Material: Alloy Steel
• Pin Type: Cotter Pin
• Pack Quantity: 10
• Weight: 0.05 pounds

Fitment

Universal fit for propeller nuts and hardware calling for a 1/8 x 1-1/4 inch cotter pin, including Evinrude/Johnson and OMC applications using OEM part number 314502.

Replaces (OEM)

• 314502

Frequently Asked Questions

What size is the Sierra 18-3742-9 cotter pin? The Sierra 18-3742-9 cotter pin measures 1/8 x 1-1/4 inches.

How many pins come in a pack? The 18-3742-9 is sold in a pack of 10 cotter pins.

What material is this cotter pin made from? It is made from alloy steel, which resists corrosion in marine use.

What OEM part number does the Sierra 18-3742-9 replace? It replaces OEM part number 314502, used on Evinrude/Johnson and OMC applications.

Is this a genuine OEM part or an aftermarket replacement? The Sierra 18-3742-9 is an aftermarket cotter pin manufactured to meet or exceed original equipment quality.

What is this cotter pin used for? It is used to secure a propeller nut and other threaded lower-unit hardware, preventing the nut from backing off under vibration.

Should cotter pins be reused after removing a propeller? No, a cotter pin such as the 18-3742-9 is a single-use fastener and should be replaced each time the propeller is removed and reinstalled.

What is included in a pack of the 18-3742-9? Each pack contains 10 alloy steel cotter pins, part number 18-3742-9.

How much does the Sierra 18-3742-9 cotter pin weigh? The pack weighs 0.05 pounds.

Does the 18-3742-9 fit both Evinrude and OMC lower units? Yes, it cross-references to OEM number 314502, which covers Evinrude/Johnson and OMC applications.