How to Install a Mercruiser Propeller

If you let a marine mechanic install a Mercruiser propeller on your boat engine, not only is it expensive, but you also miss the chance to show your family how handy you are. Even Gilligan from “Gilligan’s Island” can perform this easy, do-it-yourself boat maintenance project without upsetting the Skipper. You don’t need patients to install a Mercruiser propeller; you only need a few minutes and some common household tools.

Difficulty: Easy

Instructions

Things You'll Need:

• Leather gloves
• Marine lubricant
• Pliers
• Torque wrench

1. Place the throttle in neutral (N) position. Next, disconnect the spark plug wires from the spark plugs to prevent the engine from starting. Pull the spark plug wires from the spark plugs one at a time and label each pair with a matching number to ensure proper reinstallation.

2. Apply a thin coat of waterproof grease to the propeller shaft. This prevents the propeller hub from corroding and seizing.

3. Install the thrust washer, propeller, continuity washer, thrust hub and then the propeller nut retainer and propeller nut onto the propeller shaft. Be sure to install them in the order they’re listed.

4. Position a block of wood between the gear casing and the propeller to lock the propeller in place. Tighten the propeller nut by turning it clockwise with a torque wrench. Torque the propeller nut to 75 Nm or 55 foot-pounds.

5. Bend three of the tabs on the propeller nut retainer into the notches of the thrust hub groves to secure the propeller nut. Then reconnect the spark plug wires to complete the Mercruiser propeller installation.

Tips & Warnings

• Never rotate the Mercruiser propeller while the engine is in gear. Doing so starts the engine and can cause serious injury.

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