1966 Johnson Seahorse 3 hp, JH-21

[Rook66]

First time poster. I just discovered this fine site while searching for parts for my old Johnson 3 hp that I inherited from my uncle back in the 80s and thought I'd drop in and say hey and show what I'm working on.

I used the old motor for a couple of years and then I was transferred on my job and didn't get a chance to use it anymore. Since then it's been sitting in storage since 1988. It was running a little rough when I put it up so now I've started working on it before I run it again.

I've rebuilt the carburetor, installed new coils, plug wires, points and condensers. I'm getting ready to install a new impeller along with anything else that looks like it needs replacing.

Here are a few photos of my progress.

I was surprised to find the carburetor didn't have any gunk inside. I had run the carb dry and dumped the remaining gas from the tank when I stored it so that evidently kept it from gumming up. Here are the parts before cleaning. They look better than some I've had after cleaning in the past.

Carb cleaned and just about ready to go back on the motor.

It looked pretty clean under the flywheel.

Here it is after replacing the coils, points and condenser along with new plug wires.

Carburetor is back on and getting ready to install the armature plate and flywheel.

I'll work on the lower unit next.

 

[raczekp1]

powerhead is mesed with crankcase oil.
upper seal is leeking

 

[racerone]

raczekp 1--------But this motor does not use a seal at the top of the crankshaft.----They have a " slinger " and that slinger does not wear out !

 

[F_R]

Tuck those coil ground wires back away from the center. The way they are, they will rub on the flywheel hub and wear in two. See the pic of the originals for how they need to be.

 

[Rook66]

Tuck those coil ground wires back away from the center. The way they are, they will rub on the flywheel hub and wear in two. See the pic of the originals for how they need to be.

Yep they will rub if left like that but I'm not finished yet. The screws holding those wires have not been tightened down yet. I'm doing that as we speak. I have a coil locating ring tool that I'm using to adjust the coils with.

 

[Crosbyman]

unless proven faulty I would keep those 2 black coils.... they are not cracked liked the old style

 

[F_R]

unless proven faulty I would keep those 2 black coils.... they are not cracked liked the old style

Agreed, they more than likely are ok.

 

[racerone]

Agreed I would test those older coils on a ---MERC-O-TRONIC----magneto analyzer before tossing them, they are likely OK.-----They do not look like original 66 coils.----The condensers with the red on top do look very old.

 

[Rook66]

unless proven faulty I would keep those 2 black coils.... they are not cracked liked the old style

Not very scientific but I checked them on my multimeter and the old ones were showing something like a 3 and the new ones were at approx. 8 so I changed them out.

 

[F_R]

Even less scientific, the (actually purple-ish) ones seem to be made from a better quality of epoxy than most. Just an observation.

 

[Chinewalker]

Yep, keep those coils. Save them for some other motor you're bound to find down the line. And, no, you're not leaking oil out the top. If you were, the mag plate would be covered in goo...

 

[Rook66]

I got the coils set which was no easy task. The Sierra coils don't fit as good as the ones that came in it. There was very little room for adjustment on those coils. Anyhoo I put the flywheel back on and there's no scrapping noise when I turned the flywheel so there's no interference. I stuck the spark plugs in the plug wires and cranked the engine with a rope and there's a good spark at each plug.

I'll try to crank it up in the next couple of days. I've got to run down to the parts store and get some new gas line that I thought I had and I'm waiting on my new fuel filter that I ordered that goes in the gas tank.

 

[Bonaventure]

I would keep the old condensers as well. Newer was are often inferior in quality. If they work hold on to them.

 

[racerone]

Toss those old condensers.-----I test them warmed up using a MERC-O-TRONIC magneto analyzer.-----Test good cold and usually fail when warmed !!

 

[Rook66]

Well the latest update is not so good. I got it all back together again and it cranked up on the third crank but it's doing the same thing that it was doing the last time I cranked it up over 29 years ago. It won't run without the choke being on. Now it's back to the drawing board.

I've got the carburetor off and disassembled again and back in the ultra sonic cleaner with some stronger cleaning fluid and it's been in there for over 24 hours. I've got to order another expansion plug since they only put one of the size I need in the carburetor kit that I just installed in it. The part is cheap but the shipping charges make it pretty expensive for a little piece of concave aluminum.

If this don't work then I guess I'll have to start ordering new parts even though the needle valve, orifice plug and nozzle look good.

 

[flyingscott]

Did you clean the tank? Especially the screen in it.

 

[Rook66]

Did you clean the tank? Especially the screen in it.

Yep and I replaced the fitting with the screen on it with a new one.

 

[racerone]

Remove the carburetor drain plug.----Turn fuel on.-----Does a steady flow of fuel come out of the plug, yes or no ?---Have you tried opening the low speed mixture needle , yes or no ?----Have you checked for a blown head gasket , yes or no ?

 

[Crosbyman]

could the reeds be defective and not openning up enough on the suction pulse or... air leaking in the crankcase due to bad seals ?

with both pistons half way and ports closed anyway of pressurizing the innards with air to see if any leaks are evident

 

[Rook66]

Remove the carburetor drain plug.----Turn fuel on.-----Does a steady flow of fuel come out of the plug, yes or no ?---Have you tried opening the low speed mixture needle , yes or no ?----Have you checked for a blown head gasket , yes or no ?

At this minute the carb is disassembled and doing another cycle in the ultra sonic cleaner. When I reassemble it and put it back on the motor I'll check and see if I get a steady stream of fuel from the plug.

Yes I tried adjusting the low speed needle valve when I had it running the other day but it didn't seem to have much effect. Of course there is no high speed needle valve on this model it has an orifice plug and stud instead (items 39 and 41 in the parts diagram exploded view).

I have not checked for a blown head gasket yet. I'll do that next if it's still doing the same thing when I reassemble the carb and reinstall it.

Thanks for your time.