Free Late 50’s Johnson 35 HP Seahorse motor

[Slimcowboy1978]

I am picking up a 35 HP Johnson Seahorse made in the late 1950’s, looking at the pictures I assume it’s a 1957 or a 1958. I don’t know the condition of the motor, or if it even turns over. Assuming that I can get the motor to run again, can I use the electric start and remote controls off of my 1962 Johnson 18 HP to convert from tiller steer to helm steer for my 1962 MirroCraft Runabout?

 

[Piomarine]

It should already be remote steering and electric start. I’m certainly not an authority but I’m not aware that tiller steer was an option for 57-58 OMC 35s. I have a 56’ Evinrude Lark 30HP and tiller is not an option for that one.

There is a wealth of information available to you from the folks on this site. I am soon going to be getting back to work on my Lark and the guys on here have been invaluable in getting me to where I am thus far!

 

[Pappy]

You can for the most part.
You cannot use the 3-wire connector that enters the motor pan on the 18hp.
Control cables will hook up perfectly.
DO NOT lose the electric start 18hp stuff. That stuff is unobtainium these days.
24:1 fuel oil ratio and nothing less on the 35hp. Use only OEM parts for bringing it back into service or you will probably have to do it twice or more.

 

[wmk0002]

Nice! I would love if you would document your work on it on this forum. My dad has an one as well which he bought on an old Crosby sled tri-hull in the late 90's. We fished out of it a for few years while I was young and it eventually started gradually breaking down. I think it had never been taken too great of care of and then sat for a while and our semi frequent use of it for a few years took its toll. Anyways, its now sitting in my shop and I plan to get it going again. I ordered most of the basic parts a couple years ago including water pump parts, everything to rebuild the fuel pump, and some carb parts. I know the gearcase also needs resealing. And depending on if the electric start can or cant get repaired, we need the compression release system parts as this one didn't have it and would tear a shoulder off if you didn't start it just right lol.

 

[Slimcowboy1978]

You can for the most part.
You cannot use the 3-wire connector that enters the motor pan on the 18hp.
Control cables will hook up perfectly.
DO NOT lose the electric start 18hp stuff. That stuff is unobtainium these days.
24:1 fuel oil ratio and nothing less on the 35hp. Use only OEM parts for bringing it back into service or you will probably have to do it twice or more.

I won’t loose the 18hp electric parts. How much is a 1961 18hp worth with electric start in running condition?

 

[Slimcowboy1978]

Nice! I would love if you would document your work on it on this forum. My dad has an one as well which he bought on an old Crosby sled tri-hull in the late 90's. We fished out of it a for few years while I was young and it eventually started gradually breaking down. I think it had never been taken too great of care of and then sat for a while and our semi frequent use of it for a few years took its toll. Anyways, its now sitting in my shop and I plan to get it going again. I ordered most of the basic parts a couple years ago including water pump parts, everything to rebuild the fuel pump, and some carb parts. I know the gearcase also needs resealing. And depending on if the electric start can or cant get repaired, we need the compression release system parts as this one didn't have it and would tear a shoulder off if you didn't start it just right lol.

I plan on documenting the whole motor build here… this will be my second motor to tear down and fix up… my first was a 10hp Seahorse. I’m not any where as good as Pappy, when it comes to these old motors, but I can still tinker around with them pretty easily.

 

[Piomarine]

Our motors are basically identical you will get a lot of guidance from the thread I have on my 56 Lark. I did a near complete tear down stopping just short of pulling the powerhead.

 

[Slimcowboy1978]

Our motors are basically identical you will get a lot of guidance from the thread I have on my 56 Lark. I did a near complete tear down stopping just short of pulling the powerhead.

I read through your thread, your motor is going to be very nice when you get it back together. Congratulations on the twins by the way.

 

[Slimcowboy1978]

My buddy picked up the motor for me just a few minutes ago. The engine is already setup with electric start, so I will just need to see if it’s a 6v or 12v system.

My friend knows absolutely nothing about boats, so he didn’t really know what to look for… However he said the engine turns over with the pull rope and the recoil wind is working.

 

[Slimcowboy1978]

As you can see in the picture, there isn’t a prop… where is a good source for props for these old motors. And how do I gauge what prop to use (without tac) for my boat.

 

[Slimcowboy1978]

Is there a way to conver the pin drive prop to a more standard type of prop? Or is there a good source for finding these obsolete props?

I found that the prop is a 10 1/2” X 13” Johnson Part Number 384460. Marineengine.com wants $189.00 for it, and I found one on eBay for $160.00. What I would like to do is buy an original to keep as a spare (use at the boat show), and convert to something a little cheaper and easier to source if I have a prop strike.

 

[Pappy]

Hold off on the prop for a while. They are a dime a dozen still.
No, no easy way to convert from the pin drive. No need to either as prop shops will re-hub yours if necessary. They still do a million of them.
Check compression on the engine and check for a lot of oil/grease around the upper seal area when you get into the ignition servicing. Those are the two on the upper half that you need to worry about. No need to rebuild the engine if those are good.
We will be able to get very close on prop pitch when you get things that far along.

 

[Slimcowboy1978]

Hold off on the prop for a while. They are a dime a dozen still.
No, no easy way to convert from the pin drive. No need to either as prop shops will re-hub yours if necessary. They still do a million of them.
Check compression on the engine and check for a lot of oil/grease around the upper seal area when you get into the ignition servicing. Those are the two on the upper half that you need to worry about. No need to rebuild the engine if those are good.
We will be able to get very close on prop pitch when you get things that far along.

I pick up the motor on September 1st. 1st thing I plan on doing is the compression test. If compression tests out good, I see from the pictures that the gearbox is going to need to be re-sealed at a minimum (after replacing the impeller of course). Once I get my grubby hands on the motor I will be able to make a list of things needed to get it in tip top shape.
For sure though, I need to get new control cables. I broke my throttle cable at the end of the season last year and haven’t replaced it yet for this season. I have been to busy getting the tow rig back on the road after I lost the engine in it last fall.

 

[Pappy]

Here is pretty much what you will need to do to bring a Vintage engine back into service successfully. All parts need to be OEM if at all posssible.
Ignition service including condensers, coils, probably plug wires and boots. If the points are original and in good condition leave them in place, clean and adjust.
Carburetor cleaning. Thorough tear down including the welch plug on the top of the carburetor. Rebuild using an OEM kit that includes a new float and needle and seat. Other kits will not be complete.
Water pump. If grooved then a complete assembly is needed and recommended. Do not skimp on what cools the engine.
Gearcase re-seal. The one seal that I guarantee needs to be replaced is the hardest one. That is the shift rod o-ring. Replace it, the spagetti seal has to be replaced and any other seals that even remotely look suspicious. New o-ring on the propshaft bushing housing as well. Thorough cleaning and de-greasing. Inspect the drive surfaces of the clutch dog and forward gear. Any questions we will help on that.
Pressure test lightly, 3# or so will do.
There is a technique to the proper assembly of the old style cables. Failure to follow it will result in an accident in all probability. When you are at that point we will go over how to do it properly so it will stay together.

 

[Slimcowboy1978]

There is a technique to the proper assembly of the old style cables. Failure to follow it will result in an accident in all probability. When you are at that point we will go over how to do it properly so it will stay together.

This is probably going higher up on my priorities than should be… but only because my Throttle cable is broken and I have a running 1963 18 hp Johnson on the boat already. I don’t plan on this 35 hp to be ready to cruise this fall. The fall Kokanee strike is almost here, so I need the boat in the water sooner than later.

 

[Pappy]

Okay.....then am assuming you have the older cables with the removable ends?

 

[Slimcowboy1978]

Okay.....then am assuming you have the older cables with the removable ends?

I don’t have any pictures of the control box at the moment, but if I remember correctly from digging into it last year, the cable went through the rack gear and was held in place by set screw, but then again I could be totally off base with that thought. I’m heading out to the boat today to pull the cables to get measurements and so I can take them with me to the boat shop to get custom made cables next week when I pick up the 35 hp motor.

 

[Pappy]

You are going to need the cables and the ends and possibly the brass sleeves as well plus the clamps. Expensive!!

 

[Slimcowboy1978]

Can I use a newer style control box and cables and then retrofit the motor to accept the new controls?

 

[Pappy]

Yes but you absolutely have to use modern trunnion clamps. Those are what hold the black adjustable thumb screw on the new style cables. Different thicknesses so use something from the 70s on up. Do not bend and adapt. Dangerous and the cable may slip resulting in something you would not want to happen.