Bought 1962 Johnson 10HP - now what?

Just bought a 1962 Johnson 10HP outboard (QD-23) and I'm going to start reconditioning it for use at our summer place. I've got the service manual and watched tons of YouTube videos and read chats.


Where do I start? Family I bought it from said it hasn't been run in perhaps 15 years, but was stored indoors.


Starter rope won't pull (double checked in neutral), but I haven't "leaned" on it. Pull the plugs and get some lubrication going in the cylinders?
I plan to replace the water pump impeller for sure, and replace lower unit lubrication, and probably fuel lines, plugs.
Then I was going to try starting it just to see where things stood.


Thanks for any suggestions!

Pull the plugs and get some lubrication going in the cylinders?

Click to expand...

Spray a 3-5 second blast into the spark plug holes and tilt the plug holes up. Reinstall the spark plugs loosely to keep dirt out. Let it soak a day or so and then remove the plugs and try to pull it over.

Remove recoil starter and see if you can turn the flywheel .----Gently apply some pressure on the flywheel nut.--------You may be able to inspect ignition coils through the inspection port in the flywheel.If they are original they will need to be replaced.--------Pull the driveshaft out of the lower unit and inspect the bearing area just above the lower spline.

Things are going well. After just two nights of spraying into the cylinders with SeaFoam "Deep" and adding some Marvel Mystery oil I was able to put a socket on the flywheel nut and easily turn it (clockwise!) by hand. Once moving, I added some more Marvel oil, and eventually it was dripping out the exhaust port - figured this was good.

Buoyed by this, I further inspected the magneto. Points looked clean, coils look original and are cracking - sounds like this is to be expected. I plugged in one of the plugs and clamped it to the engine; turned it by hand and got a blue/white spark - great news! Same for other plug wire.

The grease/oil in the lower unit is shiny black and smells OK; I'll be cleaning/flushing the lower unit with ATF and then refilling with proper oil.

I cleaned the throttle gears and connecting shafts with WD-40; the gears are meshing properly but there is something still sticking. I disconnected the linkage between the throttle and the magneto (easy to do) and the stickiness is still there, like its hanging up on something. Once I get that resolved, I'll do a compression test and then I'm planning on starting it with a 20;1 mix (I know normal is like 24:1, some forums suggested 16:1 for initial start of an engine that has sat idle).

I don't want to jinx it, but so far I'm pretty darn happy with how this is going.

Pull the driveshaft out for inspection !

OK - will do - the goal is to examine the end that goes into the lower unit before putting any load on it? Thanks.

Latest news - its running!

Bought a compression tester and found it was a little low (50 or 60) but fairly even. I read somewhere that you need to pull "like you're mad at it" to get an honest compression reading; I figured it was low but good enough to press on and try to get it running.

Once I flushed the lower unit with ATF and refilled with proper lube, I then bought a bunch of new parts (details below) and replaced the water pump. I decided to replace the entire pump, impeller, cover, and bottom plate. The replacement was cheap enough and I figured why not. Probably only needed to replace the impeller. Remember to open the little cover on the side/middle of the piece that goes between the powerhead and the lower unit and to loosen the shift rod coupling. At first, I couldn't figure out why the lower unit wouldn't just drop out - that was why (dumb move on my part). I was very careful to not do anything that would pull the driveshaft out of the lower unit. The top of the driveshaft looked fine (splines), water pump kit came with new grease for the top, but not a new o-ring. Got one at the hardware store; the old one was in surprisingly good shape.

At that point, I wanted to try starting it so that when I replaced the coils, points, etc. I could tell if I did something or if there was a bigger mystery to solve. I took one of the old 55 gallon drums from under my swim float (it was leaking a little anyway), cut the top off, and mounted a short pieced of pressure-treated 2x12 horizontally using 1 1/2 exterior wood screws and washers, and attached 4 1x1 pieces of pressure treated wood horizontally extending at a right angle from the 2x12 to tie the 2x12 into the side of the drum. This gave me a very firm mounting point, filled the tank with water, connected the new plastic tank and hose, made a 50:1 mix (give it extra lube starting up), and primed the fuel system. Fuel started leaking out of the mouth of the carburetor - figured a stuck float. Decided to try starting anyway.

The rope starter thing on top has a metal spring coiled inside, and that was a little stiff and would rub on the concentric circles, making a very scary (but benign) noise when retracting the rope. Squirted some sea foam in there, and it sounded much better.

The needle valve on top (high-speed) was turning, but not the one on the bottom (low speed). I put on the choke and started pulling. After a few pulls, it started to catch - wow. At this point, the carburetor had stopped leaking, but my sense was it was still flooded. I took the choke off, pulled a few more times; it made some encouraging noises but wouldn't catch. Waited maybe 5 minutes, put the choke back on, and pulled some more. After a bit of trial and error, I got it to catch, but it sure did run rough, and it had to be completely choked all the time to stay running. Even got a few backfires, which sounded at first like the driveshaft was "catching" into forward despite the shift being in neutral. That worried me, since the "clunk" was pretty strong and I didn't want to damage the splines on the driveshaft. I flipped the engine around on the mount, and did a few pulls till it caught a little and watched to see if the propeller was moving - which it wasn't. Didn't want to run it too much out of water, so I flipped it around and tried again. No amount of high-speed needle valve adjustment would keep it running without choke (which makes sense given it was not running at high speed). So, I viewed my first try as a success and went on to replace what I knew needed replacing.

I knew from this and other forums that the coils needed to be replaced. At first I did a dumb think and tried to pop the flywheel off using a dead-blow hammer from the side. Ended up breaking one of the cast-aluminum brackets on the side - thank goodness MarineEngine had one! So then wised up and got the three-spoked puller at my local auto shop; the bolts were not the correct size so I got the correct sized bolts and washers at the hardware store. I didn't get anything special - should have gotten the stronger grade because the bolts did bend a little when used them to keep the flywheel from turning as I was tightening the puller. Finally got the puller tightened to where it went "pop" and the flywheel was loose. Took pictures, and replaced the coils and condenser one at a time. The points looked decent, so I avoided changing them right now - again, wanted to be able to tell if it wasn't working due to something I broke or was a deeper mystery. Putting the flywheel back on clearly showed that the coils were not aligned properly - the flywheel was binding when the magnet inside went past the coils. The manual talks about a special ring used to get the coils into the right position, but I found that ensuring they didn't stick out past the little "nubs" on the very front edge of the magneto plate was the key. Got the flywheel back on - lining up the keyway was a little scarey since the camshaft kept raising up on the spring underneath it making it hard to tell if the keyway was really lining up, but once the flywheel was seated and the space at the top of the shaft exposed above the nut looked correct, I figured it was OK. Gave it a few pulls without plugs connected to ensure there was still a spark, and called that part done.

Given the rough running and having to keep the choke on to keep it running, I figured the carb needed cleaning; that the engine was not getting enough fuel to stay idling at non-choke. I had also bought a carb rebuild kit, and went about cleaning the carb. Took lots of pictures, removed the link between the throttle plate and the assembly with the rubber wheel that is pushed by the plate under the magneto moved by the throttle - this is what sets up the carb for the 'start' position. Disconnected the choke lever (very small cotter pin, washer and pin), unbolted the carb and took it into the basement to a quiet place that I could work on it. Took more pictures, and pulled off the bowl. There was clearly crud in the bowl, sort of a white powder that had caked up a bit, and then clearly a build-up in the low-speed needle at the very bottom - explaining why the low-speed needle would not turn. The float was in surprisingly good shape, and so was pretty much everything else. High-speed need was clean and properly shaped. Low speed needle did come out, but the tip had lots of build up and crud and pitting. Drat - MarineEngine did not have one, but found one on Ebay. I disconnected all the needle valves, their packing nuts, the float, float needle valve and its orifice, and the high-speed orifice in the very center. All were easy to remove, mostly brass with nice slots for a stout screwdriver. Used carb cleaner to wash everything well, and then soaked the carb and the bowl in acetone overnight in a coffee can. More carb cleaner the next day with a toothbrush and all the openings were now looking very clear; you could only see the grey metal of the carb or bowl body - no built up stuff anywhere. I pulled the old packing out of both needle valve openings, and debated removing the welsh plug on the very top that clearly connected the high-speed adjustment to the holes that sent gas into the carb throat past the throttle just to make sure those openings into the carb body were free and clear. I decided against it based on stuff I read. Lubed up all the linkages, and after using most of the rebuild kit, I still had several O rings and welsh plugs not used/needed. The manual said to put three packing washers in each needle valve opening, but all the drawings showed two. The rebuild kit had exactly 3 for each needle valve, so I went with that. I did need to use needle-nosed pliers to bend the metal support on which the float goes in order to make it lay parallel to the carb bowl edge when the carb was upside down. Reassembled on the motor, primed it, engaged choke, and it coughed on the 2nd pull. Pushed in choke, and it fired right up and ran pretty well at idle.

I set the needle valves as described in the manual; turning clockwise until they are lightly seated, and then backing out a specific number of turns (in the manual). I've read some other procedures, and will perhaps try them at some point.

I don't know how rough it should be at idle; I may replace the points to see if that helps, and then get it onto the water to do some more running at full throttle, etc.

OK - here's a summary of costs:
Engine (or should I say motor) on craigslist - $350
Replacement parts - coils, condensers, points, water pump, carb rebuild, plugs - $150
ATF to flush lower unit, lower unit oil (still have a bunch left), sea foam, mystery oil - $20
Puller for flywheel - $30 Compression tester was $30, but now I have that for other things so I'm not counting that

Total is $550. Probably a bit more than I would have spent on a running 1962 Johnson 10HP, but this one is very clean, now has a bunch of new parts, and was a fun project (for me and my son) that should let me service this myself in the future. Lots of great advice, sometimes conflicting , on this (and a few other) forums.