How to Install Your Mercruiser Propeller

Installing a Mercruiser propeller correctly requires consideration of several key steps, as outlined below.

Steps

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    Read your Owner's Manual.
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    Inspect your prop blades for damage.
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    Inspect your prop center hub.
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    Disconnect the engine battery or turn off the battery switch.
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    Gather together all prop installation items such as your Thrust Washer, Hub Kit, Locking Tab Washer, Splined Washer and Nut.
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    Size your prop nut and get the correct size wrench. Most Mercruiser Alpha and Bravo One drives use a 1-1/16" size wrench. A deep socket with a breaker bar works very well.
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    Clean your propeller shaft making sure to clean out each and every spline groove.
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    Inspect your propshaft seals for fishing string, rips, corrosion damage or oil leaks.
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    Slip your thrust washer up onto the propeller shaft so it neatly seats up against the propshaft chamfer .
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    Grease your propshaft with Mercruiser Anti-Corrosion Grease, Mercruiser 2-4-C grease or Special Lube 101.
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    Insert FloTorque Plastic sleeve if so equipped.
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    Insert the FloTorque II splined hub.
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    Install the prop onto the propshaft until it goes all the way forward against the thrust washer.
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    Install a new locking tab washer.
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    Install the prop nut using the correct wrench.
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    Torque the prop nut (Alpha and Bravo One to 55 feet (16.8 m) pounds. You can use a board between the prop and the cavitation plate to keep the prop from turning. Use care not to crack the plate.
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    Spin the prop by hand to make sure it clears the trim tab anode and that it is not binding or rubbing the case.

Tips

  • Keep a spare Flotorque II hub sleeve kit on board as well as a propeller wrench in case you "spin" a prop hub from impact.
  • Cleaning and greasing the propshaft will make it easy to remove later on. failure to grease the shaft can cause the prop to be stuck on the shaft.
  • Bravo III props require a special Propeller nut Tool to remove and install the large forward propnut. Email sterndrives.com for the proper part number of the tool.
  • Mercruiser sells a neat floating propnut wrench which is good to keep on board.
  • Grease your propshaft every season.
  • Only install a good prop. A bad prop can have poor performance and it can ruin your drive.
  • Make sure your prop allows your engine to reach it's rated WOT (wide open throttle) RPM's. Check your engine manual for the correct RPM specification.
  • Inspect your propshaft seals before installing the prop. Fishing string can get around your shaft and ruin the seals. Have an experienced Mercruiser shop replace the seals if needed.
  • Stainless props cost more money but usually perform better and last much longer.
  • Not all props have the easily replaceable FloTorque II sleeve. Some have a rubber hub pressed into place at the factory. A good repair shop can install a new hub if needed.
  • Use a good grease such as Special Lube 101, Mercruiser 2-4-C or Mercruiser Anti-Corrosion Grease.
  • Test run the boat and make sure there is no vibration.

Warnings

  • Disconnect the boats battery(s) or turn off the battery switch before servicing the prop.
  • Never start the motor until you are sure the prop is clear and no people or children are close by.
  • Never start the motor with swimmers in the water.
  • Abide by all safety precautions in your manual.
  • Propellers can be sharp. Use gloves to prevent cuts.
  • Read your owners manual.

Article Info

Categories: Boat Motors and Marine Engines