Johnson Seahorse TN-28

[mindspin]

Hi All,

First time post and brand new owner of a 1952 (or 1953?) Johnson Seahorse TN-28 that I just picked up from a neighbor who was cleaning out his garage. He said his father purchased it new at the time but it has been sitting around for about 20 years. He last had it running about 2 years ago. The motor isn't frozen and I'd like to use this as a learning project so my first question is, where to start? I would eventually like to paint it but first want to take it apart and rebuild what I can without dumping hundreds of dollars in to it. I'm no mechanic by any means but I feel I have enough experience to get this thing running again.

 

[mindspin]

Re: Johnson Seahorse TN-28

I'm unable to edit my post but was going to add that I read the FAQ post where it mentions to take everything apart which I will do but what is the easiest order to do all of this? I noticed the gas tank is full of white almost clay-like gunk so that will need to be cleaned out. The carb will need to be cleaned, etc. I'm not sure about the flywheel or the lower unit yet.

 

[kfa4303]

Re: Johnson Seahorse TN-28

HI mindspin. Welcome to iboats. Nice find. When you're bringing one of these old gems back to life, it's best to be systematic. I generally start by checking the compression using a proper tester. You should get around +60 psi in each cylinder and they should be within 10% of each other. Don't be surprised if it's low at first. You may want to spray a bit of PB blaster into the cylinders to help loosen them up. The compression will also improve once the motor runs and gets up to temperature. Eventually, you can perform a decarb procedure which will help even more. Even if the compression is low, it can often be remedied by changing the head gasket. Assuming the compression is ok, I would move on to the ignition. You'll need to remove the flywheel using a Harmonic balancer puller NOT a 3 jaw steering wheel puller. You should be able to get one for about $20 at most auto parts stores. Be sure to get 3 (1/4" x 20 x 3') GRADE 8 bolts to use with it as the bolts that come with the puller are usually too weak. Once the flywheel is off you can inspect the points, condensers and coils. After the ignition is ok, move on to the carb which probably just needs a good cleaning and rebuild. You can clean out the gas tank by using BBs and some gas to clean the interior after you've removed the goop that's in there now.

 

[sutor623]

Re: Johnson Seahorse TN-28

Welcome aboard! BE CAREFUL when disassembling this old fella. Parts can be a little elusive for something of this age, as you could probably guess. First thing I'd do is get a few tools needed for this type of thing. A little $20 compression tester from advanceauto, spark plug wrench, as well as a flywheel (harmonic balance) puller. If I were you I'd soak all of the nuts/bolts that you plan on removing with penetrating oil for a few days. Squirt some oil into the cylinder on the walls (3in1 or motor oil should be fine) before cranking it or you will have dry metal on dry metal. If I were you Id start by checking the compression. I always try and start every motor that I come across before I do anything. No sense in fixing something that isnt broken. That way you can usually tell where to start. Unfortunately for you you have some cleaning to do before you do so. Run it in water when you do try and start it. If the motor is getting really hot, the waterpump is probably shot.

 

[mindspin]

Re: Johnson Seahorse TN-28

Great, Thanks guys. I'll head by the auto parts store on my way home tonight.

 

[sutor623]

Re: Johnson Seahorse TN-28

Nice, didn't mean to double post there. Bad timing:redface:

 

[1946Zephyr]

Re: Johnson Seahorse TN-28

A TN-28 fortunately has a lot more available for it, than the 26's and older. Your ignition system is the universal type, used on all twins and singles from 1951 up till about 1974. The impeller is the star type, like what is used in the 5.5's but has a couple minor differences in thickness and hole diameter. If you can't find one, then the later type can be easily modified to work. I think your best bet for parts on that, is to try Sea-Way Marine, up in Seattle. They have a good stock of parts for those old Johnsons. I'm restoring a 1941 Johnson HD-20 and so far, they have helped me with everything I've needed and that includes all the innards for my powerhead. Good Luck. I hope this helps out.

 

[HighTrim]

Re: Johnson Seahorse TN-28

Unfortunately for you, a TN is probably not the best motor to learn on, they are a little different than the norm.

About the only thing "standard" on them is the ignition as Zeph stated. That is the easy part. Pull the flywheel and have a looksee, if the coils are original they will be cracked and will definately need to be replaced. The points/condensors are a judgement call upon inspection/testing. Clean up the mag plate, adjust and re torque the flywheel and you are good to go with that.

The carb is a bit different from the standard 50s OMC carbs you may be used to. These usually leak, especially at the primer plunger and the leather, (yes I said leather) seals need to be replaced. They can be bought from LLoyd Lautner of the AOMCI, PM me and Ill shoot you his contact info. Ill also post an extemely handy link for the TN motors. I read it a couple times before starting my first TN. I have 5 now I think?? There is no rebuild kit for these carbs available. If the float is shot, it will need to be made. Hopefully you will get lucky and it will just need a sanding and coat of dope.

The gearcase oil will need to be changed with new seals on the drain and vent screw. Do this before dropping the gearcase to service the impeller. This motor is not like others where the oil is self contained. Dont drain it and it will be all over your floor. The link also covers how to modify an impeller from a newer 5.5hp as Zeph also mentioned.

Read through the link and post any questions you may have. Good luck!

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

 

[HighTrim]

Re: Johnson Seahorse TN-28

Coil replacement

http://hoodad.fortunecity.com/biglures-motors.html

Gearcase Service

http://hoodad.fortunecity.com/tnlowerunit.html

 

[mindspin]

Re: Johnson Seahorse TN-28

Thanks all, I really appreciate all of the responses. I picked up a compression tester from Autozone, sprayed some PB Blaster in the cylinders and attempted to pull. I got just under 70 psi on one and ~63 or 64 psi on the other. Something sounds really awful when I pull so I'm expecting something is damaged already in the flywheel. I'll disassemble and take pictures tomorrow when it's light outside.

As for penetrating oil on bolts, etc can PB Blaster cover that as well? Is it feasible to just replace some of the bolts from Lowes?

I'm going to just rent the harmonic balancer puller tool when the time comes from O'Reilly's down the road. Everywhere I went either had steering wheel removers or really cheap bolts for the puller. O'Reilly has a "professional" grade that I can rent next week.

Good news about the impeller, if I need to, I have a really nice caliper and grinding tools that can actually be put to use.

I've read over the big lures little lures site a few times now and attempted to contact him but his email is no longer in existance. After some digging around using Google, I believe he is the guitar player "GoMez" in this band - http://www.facebook.com/Acceleratii
I haven't attempted to pester him with outboard question though

 

[HighTrim]

Re: Johnson Seahorse TN-28

Where are you from?

 

[mindspin]

Re: Johnson Seahorse TN-28

I'm in Atlanta.

 

[kfa4303]

Re: Johnson Seahorse TN-28

Hello again spin. 70 psi is actually pretty good. These are low compression motors after all. You may even see it go up a bit once its had a chance to run a bit and get warmed up. If you have the funds, I would go ahead and buy a puller. You'll end up using it more than you think and it'll save you a trip to the auto parts store to use theirs. Here's a great link for the universal magneto and a pic of how to use the puller. Keep us posted. We love pics

http://www.outboard-boat-motor-repa...on 3 HP 1952-1967 Ignition System Tune-up.htm

 

[mindspin]

Re: Johnson Seahorse TN-28

Here's some more pics taking everything apart.

Here's the first problem I see so far, broken spring, missing spring and a rusty spring.

To remove the gas tank, I had to take off the 3/8" carb primer pump nut and the fuel line.

The cleanest part of the outboard is under the gas tank.

 

[bonzoscott]

Re: Johnson Seahorse TN-28

Is that the motor that was on Craigs List in Blue Ash? If so I tried to get it. I too am re-working a TN 28, but mine is missing parts.

 

[mindspin]

Re: Johnson Seahorse TN-28

No, assuming you mean Blue Ash, OH. I'm in Georgia.

There's somebody currently on ebay selling parts from a TN-?. Look up "economymarinellc". There's also another guy selling parts from a TN-26, "gabeyb2001". I'm not sure how much of that stuff would work or not on the TN-28.

 

[mindspin]

Re: Johnson Seahorse TN-28

Does anybody have any advice how to get this flywheel off with the harmonic balancer puller? I've been trying to follow http://hoodad.fortunecity.com/biglures-motors.html but hitting it with a hammer does nothing and I don't know how I can possibly get it on any tighter.

 

[HighTrim]

Re: Johnson Seahorse TN-28

Ok so you removed thed 3/4 nut and washer right?

Silly question but have to ask.

They use the 3 grade 8 bolts that you got and thread them through the puller into the flywheel 7/16" deep equally. I mark 7/16" up the bolt with a sharpie marker so I know when to stop threading them in. Stack some washers under the heads of the grade 8 bolts, 1 thin one will twist/warp. Start tightening the main puller bolt with a wrench. I have had to add a pipe on the end of the wrench to crank on the puller bolt. She will pop. Dont let it frighten you when it does if it is your first time Dont worry, you didnt break anything! Makes it easier if you have a helper to hold the flywheel with a strap wrench while you pull on the wrench.

If you hit the top of the puller bolt with a hammer, be sure to pull UP on the flywheel before hitting it or you will damage the bearing.

 

[HighTrim]

Re: Johnson Seahorse TN-28

I'm in Atlanta.

Ah ok you are a little far from me.

 

[mindspin]

Re: Johnson Seahorse TN-28

Ok so you removed thed 3/4 nut and washer right?

Silly question but have to ask.

Yeah, that was the easiest part so far. Don't worry about silly questions since this is the first time I've ever worked on an outboard, I will probably have a ton of simple questions as I go.

They use the 3 grade 8 bolts that you got and thread them through the puller into the flywheel 7/16" deep equally. I mark 7/16" up the bolt with a sharpie marker so I know when to stop threading them in. Stack some washers under the heads of the grade 8 bolts, 1 thin one will twist/warp. Start tightening the main puller bolt with a wrench. I have had to add a pipe on the end of the wrench to crank on the puller bolt. She will pop. Dont let it frighten you when it does if it is your first time Dont worry, you didnt break anything! Makes it easier if you have a helper to hold the flywheel with a strap wrench while you pull on the wrench.

I bought three 1/4"-20 Grade 8 bolts but just guessed the thread depth and tried to get them roughly even, I'll try marking 7/16", good idea. I thought the same thing about the washers and I tried using the recoil part as demonstrated in the BigLuesLittleLures site but it easily bent so I've got 3-4 washers on each bolt now.

If you hit the top of the puller bolt with a hammer, be sure to pull UP on the flywheel before hitting it or you will damage the bearing.

Yeah... it's probably safe to assume at this point I've already damaged the bearings. :facepalm: You don't want to know what I've done to this thing already. Hopefully its not too bad.

Thanks!