1972 18hp Evinrude impeller replacement?

[Teutonics]

Hi all,

I'm trying to get my dad's old fishing boat operational again for his retirement this year. The boat has been sitting for many years, but overall is in good shape. I got the engine running, but was afraid to run too long (only a minute or so) because I am not sure of the condition of the impeller. It was spitting water out the back, so I'm assuming that it is working at least in part, but I would like to replace it for peace of mind.

Can anyone provide instructions on how to replace the impeller on this engine? I tried searching the archives here on iboats and doing a google search, but came up with nothing.

Thanks for the help!

 

[Paul Moir]

Re: 1972 18hp Evinrude impeller replacement?

It's very simple but you should get yourself a service manual. You can often borrow one from the local library if you don't wish to purchase one. If you do wish to purchase one, we can point you in the right direction.

But you're wise to replace the impeller now that you've got it to fire. May I suggest you get the water pump kit with a new wear plate & grommet in addition to the impeller if it turns out your housing is ok?

Step 1, remove the l/u. Remove the shift connector access window (2 screws) on the side of the midsection. Completely remove one of the two bolts from the shift rod connector. Remove all the bolts that hold the lower unit on. I think those have 6 easily identified ones. Pull the lower unit off.

Step 2, replace the impeller. Remove water pump housing. Do not pull up on driveshaft at this point. Remove impeller. Remove impeller key (if removable) and set aside. Remove wear plate (if replacing). Clean corrosion, etc, and examine water pump housing for gouges, wear, etc and replace if necessary. If it is necessary to replace, you'll need an entire water pump from the dealer because the new one is completely different from the old metal one and takes a different impeller. Put sealant on the mating surface between the lower unit and the wear plate (this step is optional). Place on wear plate. Place impeller key back in. Install impeller. Install housing over impeller, turning the driveshaft clockwise as you lower it over so the impeller's vanes bend into it. Screw in housing screws but before and while tightening turn the driveshaft a little to make sure the impeller doesn't get pinched. A little soap makes this task easier.

Step 3, install lower unit. Put a light coat of grease on the driveshaft splines and replace the o-ring there if bad. Install the lower unit aligning the driveshaft, shift shaft, and water pump as you do. I strongly recommend you first look up the midsection with a flashlight so you can see where the driveshaft must go. Often the driveshaft or flywheel will need to be rotated slightly.
Bolt the lower unit back on. Ensure the shift rod has completely gone into the coupler by verifying the position of the divit in it with a flashlight. Install the bolt, but just snug. It is not a clamp. Replace the access window.

All screws should be painted with sealant to prevent corrosion and make removal much easier. Replace impeller every few seasons at a minimum.


That's all there is to it.

 

[Teutonics]

Re: 1972 18hp Evinrude impeller replacement?

Outstanding! Thanks for the help!