Got it running like new
October 22, 2013 at 9:51pm
Well, after researching the subject and determining that it was not worth it to pay a mechanic to work on it, this was my project for the past 3 weeks and I thought I would share the story with you. I was considering buying a new 4 stroke or slightly used 2 stroke 15 hp for my recently acquired 16 ft jon boat. I was asking around at work and some I work with said he had a 1974 Johnson 15 hp I could have for free if I wanted it. It was his deceased Uncle's kicker on his cabin cruiser and had sat for at least the last 10 years unused in his garage. He gave it to me along with the original 6 gallon metal gas can. It appeared that it had been fogged and stored properly, because it turned over fine and the plugs were oily. Brought it home and checked compression. 110 PSI in each cylinder, which is exceptional and a good indicator of the quality of an outboard. So, determining that it was worth sinking some money into it, I bought an original service manual off of Ebay and got to work. Here's what I did.
1. Pulled the flywheel and cleaned/set points (ignition parts were in excellent condition)
2. Replaced fuel pump (there was a tear in diaphragm of the old one)
3. Rebuilt carburetor and replaced spark plugs
4. Replaced all fuel lines
5. Replaced water pump and thermostat
-While dropping the lower unit to replace water pump, discovered the drive-shaft was stuck/rusted up in the powerhead so I had to put it upside down for 3 days and spray penetrating oil down there to soak it. Finally got it unstuck with vise grips and a big hammer!
6. Retrofitted a water telltale for it by drilling into the water
jacket and installing an elbow and hose. (74-76 models didn't have the water indicator)
It now runs like the day it came off the assembly line in 1974! I took it out this past Sunday on the river and in the swamp around our house and ran it for 3 hours on the boat. Pushes the boat about 20mph with 3 people. I was skeptical of how
well it would turn out, but am tickled pink with the results.
Total investment was about $300 in parts and lots of labor. These old motors are engineering marvels and are incredibly reliable, but as you all know, no one will work on them anymore. Mostly because today's mechanics haven't seen them before and don't know anything about them. And it's just not worth it financially to the owner. Anyway, just thought I'd share this story with ya'll. Quality old motors can be just as good or better than new ones if you have the skills to repair and maintain them.