Install Your Mercruiser Propeller

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

Steps

Read your Owner's Manual.
Inspect your prop blades for damage.
Inspect your prop center hub.
Disconnect the engine battery or turn off the battery switch.
Gather together all prop installation items such as your Thrust Washer, Hub Kit, Locking Tab Washer, Splined Washer and Nut.
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.
Clean your propeller shaft making sure to clean out each and every spline groove.
Inspect your propshaft seals for fishing string, rips, corrosion damage or oil leaks.
Slip your thrust washer up onto the propeller shaft so it neatly seats up against the propshaft chamfer .
Grease your propshaft with Mercruiser Anti-Corrosion Grease, Mercruiser 2-4-C grease or Special Lube 101.
Insert FloTorque Plastic sleeve if so equipped.
Insert the FloTorque II splined hub.
Install the prop onto the propshaft until it goes all the way forward against the thrust washer.
Install a new locking tab washer.
Install the prop nut using the correct wrench.
Torque the prop nut (Alpha and Bravo One to {{safesubst:#invoke:convert|convert}} 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.
Spin the prop by hand to make sure it clears the trim tab anode and that it is not binding or rubbing the case.

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.
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.
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.

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.