How to Change a Propeller on a Johnson 70-Horse Outboard

The Evinrude and Johnson motors are close cousins, using the same parts.

When you need or want to change the propeller on a 70-horse Johnson outboard motor, perhaps because your boating needs have changed, you'll find the task no more onerous than removing the propeller for winter storage. The 70-horse Johnson is a four-stroke outboard built by Bombardier Motor Corporation, the successor to OMC, Ole Evinrude's Outboard Motor Corporation that produced Johnson and Evinrude motors from 1929 until just past the turn of the century. Even with new ownership, though, the basics of the Johnson outboard haven't changed.

Things You'll Need

• Pliers
• Plank or block of wood
• Box/open-end wrench
• White marine grease
• Torque wrench
• Pipe

Instructions

1. Move the engine's shifter into neutral. Twist the connectors to the spark plugs and remove the wire from each plug to keep the engine from being started accidentally.

2. Insert a piece of scrap wood between one of the blades of the propeller and the anti-cavitation plate above the propeller, to keep the propeller shaft from turning as you remove the propeller nut. Remember that you'll be turning the nut counterclockwise, so turn the propeller blade counterclockwise to jamb the wood in place, as well.

3. Use a wrench, box end or open end, to remove the propeller nut, removing the scrap wood when the nut is loosened. Slide the washer, spacer, propeller and thrust washer from the propeller shaft. Remove any fishing lines, weeds or other things that may have accumulated on the propeller shaft and at the face of the gear case, and grease the propeller shaft with white marine grease.

4. Slide the new thrust washer onto the shaft with its raised shoulder facing away from the gear case. Slide the propeller onto the shaft so that it fits onto the splines of the propeller shaft and is seated against the surface of the thrust washer. Slide the spacer onto the shaft, over the shaft's splines and finally, slip the washer onto the shaft.

5. Jam the propeller in place with the scrap wood once more and thread the propeller nut onto the propeller shaft. Use a torque wrench to tighten the propeller nut to 36 foot-pounds of torque; tighten the nut further, until you see that the hole in the propeller shaft and the nut slots on the propeller nut are aligned, without exceeding 43 foot-pounds of torque. Slip the cotter pin through the nut and shaft and spread its split ends with your pliers.

Tips & Warnings

• Since the propeller nut was torqued into place, you may find it easier to slide a length of pipe over the handle of the wrench to effectively lengthen the wrench's handle and reduce the effort need to remove the nut. Remember that mechanically, a wrench is a form of lever: the longer the lever, the easier it is to move things.

• Although statistics on propeller-strike injuries are hard to find, if you work on your outboard motor when your boat is on its trailer, or your motor is on a storage stand, remove the propeller: pull the cotter pin from the propeller nut, remove the propeller nut with a wrench and slide the thrust hub, propeller and washers from the propeller shaft. Failure to remove a propeller before operating an outboard out of the water is an invitation to a propeller-strike injury, which can maim or kill. The Johnson 70 Operator's Guide says it best: "Damage to your boat and outboard can be fixed in a short period of time, but injury or death has a lasting effect."

References

• Bombardier Recreational Products: Operator's Guides -- Johnson 4-Stroke 60/70 Horsepower
• Funding Universe: Outboard Marine Corporation
• Reference for Business: Bombardier Inc. -- Company Profile