Johnnyrude hydroelectric impeller tutorial

halfmoa

Ensign
Joined
Aug 19, 2011
Messages
955
I humbly submit a tutorial on how to replace the impeller on a hydroelectric shift Johnson/Evinrude outboard motor.

To start, this is a 1972 Johnson 65hp engine, model 65ESL72S, mounted on the transom of my 16' 1972 Starcraft Super Sport.

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To replace the impeller you're going to need a 3/8[SUP]ths[/SUP] drive standard socket set with 6 inch extension, liquid soap, electrical tape, about 15 feet of strong cord (I used 550 paracord but in the future I'll use 40lb mono), electrical tape, marine grease (ANY grease is better than no grease at all:) ), anti-seize, a helper, and of course a replacement impeller.

Step one is to remove the cowling and locate the solenoid control wires seen here.

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Slide the protective insulation away from the lower unit and disconnect the knife connectors. At this point you need your cord and tape handy. You're going to tape the cord to the wires that lead towards the lower unit. (If you don't know how to tape off wires to pull with a cord now would be a great time to look that up...you don't want to lose these suckers.) Tie off the pulling cord so you don't end up pulling it clear through. I also labeled the green wire. It's colored but those of us who are blue/green colorblind need it labeled. Soap up the wire loom and taped connection, and remove the loom from the hook on the reed box.

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Make a mark on the antiventilation plate indicating your trim tab position,take the four outer bolts that hold the lower to the exhaust leg completely out as well as the "hidden" bolt located under the trim tab as shown here.

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To be continued....
 

halfmoa

Ensign
Joined
Aug 19, 2011
Messages
955
Re: Johnnyrude hydroelectric impeller tutorial

After removing the "hidden" bolt remove the large bolt just behind the trim tab on the antiventilation plate. At this point your helper should be near by as the lower will separate. Go slowly and feed the wire through the top towards the lower unit. If the wire stops you're going to have to stop and tape it again minimizing the bulk of the taped connection (ask me how I know).

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The separated lower unit is shown below. The large shaft protruding upward is the drive shaft, the smaller plastic tube is a guide tube used to guide the water line into place during re-installation. If it's missing you need to check further up the water line in the exhaust leg. The water pump assembly is the piece bolted to the lower unit around the drive shaft. Take note of the wire attachment points. Also note the cord still taped to the wires.

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Free the wire from the tabs holding it in place and unbolt the water pump from the lower. When sliding the pump up the drive shaft watch for the woodruff key and grab it if it moves out of place. Shown below is the bottom side of the pump after being liberated from the lower and slid off the drive shaft with the old impeller still in place.

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Lube the inside of the housing with a little liquid soap and install the new impeller in the housing paying attention to keep the vanes turning in the same direction.

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Slide the pump assembly over the drive shaft and position the impeller over the woodruff key. I find that a little grease holds the key in place quite well. Bolt the pump back to the lower unit. Don't forget anti seize on all bolts!

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To be continued....
 

halfmoa

Ensign
Joined
Aug 19, 2011
Messages
955
Re: Johnnyrude hydroelectric impeller tutorial

Below is the lower with the pump reinstalled. Note the wire retaining tab re-installed in the same position. Also note the round passage to the lower right side of the drive shaft. That's where your guide tube goes.

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Install guide tube by sliding it into place and reattach the wires in the same position they were in when you removed the lower unit. Clean then grease the top of the drive shaft. Here's a pic of the clean shaft with a new O ring and marine grade grease in the background.

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Installation is the reverse of removal. I found that installing the large center bolt first was easiest. Use anti seize on all bolts and don't forget to properly align your trim tab with the mark you made earlier. Keep that Johnnyrude alive with a new impeller! You can do it!

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rockyrude

Lieutenant Junior Grade
Joined
Sep 10, 2007
Messages
1,120
Re: Johnnyrude hydroelectric impeller tutorial

Thanks for submitting that well documented piece. Should save a lot of frustration.
 

halfmoa

Ensign
Joined
Aug 19, 2011
Messages
955
Re: Johnnyrude hydroelectric impeller tutorial

Thanks for submitting that well documented piece. Should save a lot of frustration.

Thanks rockyrude! I know there's still boaters out there who run these engines and since the process is a bit different I thought I'd contribute.
 
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