1980 Johnson 115 J115MLCSA impeller

[cbmma1978]

New to the forum..thanks in advance for the help.
I have the motor listed above....How bad a job is it to change the impeller? Is this something I can do myself? Do I need to pull the lower unit off? What, if anything will fall out if I do pull the lower unit? Advice? Should I plan on getting a waterpump rebuild kit, or can I get away with just getting an impeller? Any seals or o-rings I should get? I am pretty good with mecanical things, but my experience is with cars and motorcycles..not boat motors.
Help.....

 

[Joe Reeves]

Re: 1980 Johnson 115 J115MLCSA impeller

The water pump sits directly on top of the lower unit. THere are times where one can get away with replacing just the impeller BUT I would suggest that you install the complete water pump kit (inclides everything). This eliminates any possible problem that might exist in other areas of the pump that might go undetected.

Obviously the lower unit needs to be dropped. If you intend to keep that engine for awhile, doing your own work, it would be a good idea to purchase a servive manual to avoid possible expensive mistakes.

 

[cbmma1978]

Re: 1980 Johnson 115 J115MLCSA impeller

Thanks to the advice of several list members, I bought a manual, and a full waterpump repair kit. My buddy and I had at the lower unit. Getting the pin out of the shift rod was a bit tricky, but after that, the lower unit came off easily. When off, we were shocked to find that the reason we were getting no water out the **** hole was that there was NO WATER PUMP on the motor. Appearantely, the P.O. had removed it, planning on replacing it, but sold the motor before he did. Good thing we had not run the motor for more than a few seconds..... Anyway, we put in the new waterpump, button her up, and fired her up for about 3 seconds...NO WATER circulation. What????? Took her apart again, and found that the woodruff key had fallen out when we put the waterpump on. DUHHHH...
Ok, let's try again.....Got the water pump reinstalled, with the woodruff key in place. Tested the lower unit in a sink to make sure the pump is now pumping..didn't get water out, but we could not turn the shaft fast enough by hand. The good news is that we could hear the impeller trying to suck water. Tomorrow, we put the lower unit back on, and try it again. Wish me luck....

 

[cbmma1978]

Re: 1980 Johnson 115 J115MLCSA impeller

Today, we put the lower unit back on the motor. Fired her up...SHE LIVES! Pumps water great. Motor ran a little rough at first (hey, it was all of 38F out, and the motor hadn't been run in at least 3 years)...when she warmed up, it settled right down to a nice steady idle. Took throttle well, with no balk or stutter. Could not go WOT, as we were running in a plastic tub of water, but I believe she will really rip.
After running her for about 15 mins at idle, we shut her down, and pulled the plugs and ran a compression test. Top two cly each had 120 lbs. Bottom two both had 118 lbs. Sounds good to me.
Then ran a leak-down test. NO problems there either.
I believe we have a winner.
Next weekend we take her out on the lake for a shake-down run.
Thanks for the help, everyone.