Johnson Seahorse revival

[burnt clutch]

Hey there I just acquired this Johnson Seahorse model TN-28. When I was inspecting it I noticed that there was liquid in its gas tank. I emptied the tank into a old coffee can and the liquid that came out was milky and smelled sort of like weak turpentine. I looked into the tank and saw some thick milky residue so I put some pea gravel in the tank, filled it with water, put the gas cap back on and then I sloshed the tank around for several minutes to break the residue up. I emptied and repeated this a few times and as far as I can tell the gunk is out of the tank. Is it possible that the stuff that I found is just old gas that had broken down? Since this tank is aluminum should I re-use it as it is or should I treat the inside of it with a epoxy to seal/protect the aluminum. Also is there a online source for manuals for this engine? I want to take the carb apart and see how much of this gunk is inside of it. Thanks in advance for your help!
-Karl

 

[1946Zephyr]

Re: Johnson Seahorse revival

Cool. You found an old TN. I happen to own a TN-26 and a TN-27.

Yep, you guessed it. Antique gas and it's the nastiest stuff on earth. You likely will need to pull your carb apart, unless the previous owners were smart enough to shut of the petcock and drain the carb. A lot of us aren't that lucky, but you can put fresh new gas in the tank and see what happens. Just pump the primer (push down on the high speed knob) and you should see fuel mix come out the front, where the low speed needle is, then giver 'er a pull. I got my TN-26 running the other day, after just filing the points and puting fresh gas in it, so you might get as lucky.

The TN-28 uses the unversal style ignition, which is found on all OMC twins and singles, from 1951(52) on to in the mid '70's You'll most likely need a new impeller too.

 

[HighTrim]

Re: Johnson Seahorse revival

The impeller you can order from F_R on this forum, PM him for details. They do not make it any longer.

This page will help with the TN, quite educational.

http://www.pochefamily.org/outboard/

I would start with a compression test first, let us know what you find.

 

[1946Zephyr]

Re: Johnson Seahorse revival

You want to make sure the mix on those are at 16:1. The TD/TN/HD series motors will have trouble idling right, if they have been ran for any length of time, with too lean of a mix. The premature wear on the main journals will allow leakage between cylinders and create issues with a low idle. Although compression is important, this issue is too. Not to worry though, there are bunches of these motors out there and finding a parts motor will be quite simple. The AOMCI is a great place to get parts if you need them.

Thanks for that info, Chris. I may give F_R a shout for a couple of those soon. And thanks for posting that link.

 

[HighTrim]

Re: Johnson Seahorse revival

Here is Franks website. It does not mention the impeller but he sells them.

http://mysite.verizon.net/respdyk0/

 

[burnt clutch]

Re: Johnson Seahorse revival

Thanks for the replies and the links- that info was exactly what I was looking for! About that screen in the fuel tank petcock. The screen fell off when I was cleaning the tank and I guess I need to glue that back in. Are there any other products that I can do this with other than the CA-glue gel that he references? I was thinking of using a fuel resistant RTV gasket compound but wanted to run that by you all first .
-Karl

 

[burnt clutch]

Re: Johnson Seahorse revival

I figured out that the CA glue is really superglue so I got some and glued the fuel tank screen into the petcock. I got everything assembled ? added some fresh 16:1 gas but she won?t run. I?m not getting any spark so I guess my coils are shot. My next question ? in order to get the flywheel off do I need to remove this center nut, or is that just part of the crankshaft? I?m getting a flywheel puller from the FLAPS on the way home to get this torn down.

 

[HighTrim]

Re: Johnson Seahorse revival

You need to remove the nut, then thread the puller bolts into the 3 holes you see. The little TN flywheels usually pop off pretty easy with a home made knocker tool though.

By the way, your coils are most definately shot, I can see them through the inspection port, they are original and cracked.

 

[burnt clutch]

Re: Johnson Seahorse revival

You need to remove the nut, then thread the puller bolts into the 3 holes you see. The little TN flywheels usually pop off pretty easy with a home made knocker tool though.

By the way, your coils are most definately shot, I can see them through the inspection port, they are original and cracked.

Yeah, they are pretty crumbly. What is the best method for breaking the nut loose? I can't find anything to hold the flywheel in place. Is this nut torqued down pretty tight?
-Karl

 

[HighTrim]

Re: Johnson Seahorse revival

I use an air impact gun, but if you do not have a compressor and tools, either use a wrench while someone holds the flywheel by hand, or with a strap wrench, or an old belt. Another option is to put a wrench on it, and give it a quick wrap with a hammer. That will loosen the nut for you.

When all done, retorque flywheel to 40 ft/lbs

 

[bonzoscott]

Re: Johnson Seahorse revival

Stuff soft rope in a cylinder (piston down) and turn the crank nut until it seizes up to break the nut free - reverse for torquing it back down (40lbs).

 

[burnt clutch]

Re: Johnson Seahorse revival

I'll try the rope trick tonight. As for replacement coils, what brand is the best? Are the Sierra ones any good?
-Karl

 

[bonzoscott]

Re: Johnson Seahorse revival

From everything I've read on here, people are satisfied with the Sierra coils. I would just get the OMC (BRP) coils. Maybe only a Buck more - around $18 each. PM me your email and I'll send you a bunch of files/pics involved with my TN28.

 

[burnt clutch]

Re: Johnson Seahorse revival

From everything I've read on here, people are satisfied with the Sierra coils. I would just get the OMC (BRP) coils. Maybe only a Buck more - around $18 each. PM me your email and I'll send you a bunch of files/pics involved with my TN28.

I jumped the gun and bought the sierra coils from iboats as I didnt see any negative reviews on them. I finally got the flywheel off last night and the rest of the setup looks complete (no broken wires, or rusty points). From pictures of the replacement coils it looks like one of the mounting holes is elongated so the coil postion can be adjusted, but with the lip of the flywheel I dont see how. Do you adjust these through the inspection hole in the flywheel?
-Karl

 

[HighTrim]

Re: Johnson Seahorse revival

They are adjustable. It is the coil to magnet air gap. You want the laminations flush with the mounting boss. Run your nail across them, if they are out too far, they will hit the flywheel, too far in, weak or no spark.

 

[kfa4303]

Re: Johnson Seahorse revival

Can't help much with the motor, but it's good to see another Karl ( with a "K") in the forums Sprechen Sie Deutsch?

 

[burnt clutch]

Re: Johnson Seahorse revival

Nein, just what little I know of from working on VW's. Here's the latest -I installed the coils and got everything looking like this ?

I squirted some starting fluid into the Carb and was able to get it to fire so I think I am good on ignition. I got the leather seals for the primer pump and re-assembled the Carb without issue. I decided to go all the way and check on the impellor and lower unit before test running the engine. I tore into it yesterday and this is what I ran into

The impellor is shot ? yay!

I have a replacement impellor on order from the FLAPS and it should be in tomorrow. My next question is what do I need to remove to get to it? Does the shock absorber/spring need to come off?

 

[burnt clutch]

Re: Johnson Seahorse revival

Here's the latest - I got the new impellor installed and lower unit re-assembled and oiled. The motor will run if I prime it heavily but it wont run for more than 2-3 seconds at a time. On top of that I have a leak in the gas tank! I've stripped the carb apart and boiled the carb body in water clean any junk out of it but that is the extent of my carb work. (I boiled the thing because I couldnt get the primer washers out and I was afraid that it I dipped the carb in any cleaning chemicals that I might damage the leather washers) When I did a compression test I got readings of 45 and 48 PSI - would that be working against getting it to run? I'm stumped on what my nexst course of action should be - short of overhauling the powerhead. Also what would be the simplest way to find a leak in the gas tank?
-Karl

 

[Chinewalker]

Re: Johnson Seahorse revival

Stuff soft rope in a cylinder (piston down) and turn the crank nut until it seizes up to break the nut free - reverse for torquing it back down (40lbs).

I know this is a couple weeks old, but please do not use the rope trick on these older motors! They have aluminum rods that are easily bent if you're hurking the flywheel while holding the piston from moving... It's doable on motors with steel rods, but the older ones with cast aluminum rods don't do well with it...

 

[nwcove]

Re: Johnson Seahorse revival

the compression numbers are on the low side, but should improve if you can get it to stay running. i also notice that the black wire on the coils isnt tucked back tight against the coil and could, or maybe already did chafe through the insulation from rubbing on the flywheel. cant really see the green wires , but they also need to be tucked away from the rotating assembly.