TOPIC: 75 hp Super Seahorse

Well after 27 years in storage I finally got the old Uniflite in the water. It ran great for about 30 minutes then I started having issues. When i would apply throttle it would die out. Then I would prime it again and apply about 1/4 throttle and it was fine, more than that it dies. I am replacing the fuel pump diaphram this week but not sure if that is all of my problem. Also when i was running it I was noticing quite a bit of steam from the shroud just above the lower unit and out of the exhaust but not a huge amount of water. The heads were hot to the touch but the overheat light did not come on. Not sure how much these old outboards should be pumping but this may be an issue too? Its a 1963 model super seahorse if that helps.

Thanks for your Help.
Nick

Replace the water pump & fuel pump. I avoid fuel pump kits. Those little white caps that go onto the little springs are just a pain. You will need to sprout a few more fingers, about the size of a 6 year old. Then maybe the kits are OK.

Jim

Heads on these engines should be warm to the touch, warm enough you wouldn't want to leave your hand on them for long. Should not be hot enough to burn your fingers. After 27 years in storage, a new water pump impeller should be considered mandatory. These engines should have quite a bit of water flowing out of the relief hole after they have been running a minute or so. As for the fuel pump, if squeezing the primer bulb when the engine starts to die out makes a difference, then that's a pretty good sign you have a fuel pump problem. I'm sure others will chime in with constructive ideas, but here is a starting point for you. Good luck!

If this were mine,(you may have done this already) every fuel component should be replaced. All fuel lines, complete carb kits, if available, fuel pump, etc.
Any tiny little piece of old gunked up oil or fuel line may decide to depart from its resting place and cause you headaches for a long time. You will be doing carb job after carb job.

Well I tore the fuel pump down and replaced the diaphram, filter and gaskets. Looked like there was a small pin hole on the vacuum inlet. I replaced all the lines before I fired it for the first time, and cleaned the carb so the fuel system should be good to go. Sooo, now on to the impeller. Not sure how big of a job this will be though. Im confident with car engines and have rebuilt several but this is my first outboard so its a bit of a learning curve.

Nick,
You're gonna do just fine with it. All it takes is a little mechanical ability and the right attitude, and you seem to have both of those. If you have a manual on the motor I suggest reading over the water pump replacement text a time or two to familiarize yourself with the procedure, (sorry I don't have any experience with that particular motor). I'm going to post a link below that contains some video on the subject I found most helpful, provided to me by a friend here. Good luck with your project, and how about posting some pics of your motor and the Uniflite when you get a chance, please. (Love those old Cabin Cruisers!)

www.fiberglassics.com/glassic-forums/j-e-g-o-s-place/1973-johnson-115esl73m-revival
(Post# 3069 contains the water pump video)

Hi Nick Nick here. I have the same Super Sea horse and rebuilt the lower unit last year. If you are going to do a lot of work on this unit yourself try getting a Parts catalog for it the diagrams have been invaluable to me. If your going to replace the impeller its an easy job and very accessible but once your in there depending on condition you may wish to replace all the seals along the shaft as well. Before you try dropping the lower unit remember to disconnect the electromatic drive cable by the power head and snake it threw the access panel on the side of the front exhaust cover. also for easy replacement use a suitably sized strong cord to follow the wires down so you can simply pull them back again. its an easy bit of work to do the impeller and you will have it done in an afternoon if no other parts need to be hunted down. I'm Having some very similar issues to yours. I had a weekend of good running out of my seahorse this spring and then it started to have some strange issues, seems like fuel supply issues but the pump was rebuilt last year and ran fine previously and on inspection looks to be good. also started overheating during prolonged idle speed operation in no wake zones and fading or stalling completely at high speed for no reason like a fuel tank was empty. I noticed you mentioned some steam visible, Is this steam from under the power head or external from the lower unit? if the steam is associated with the power head there could be a crank case gaskets leak giving lack of vacuum/pressure in the crank case and corresponding intake/exhaust issues in the cylinder regardless of compression. also check for an unnaturally clean spark plug as it could be a leak in the cooling jacket and letting water in to the cylinder. perhaps take a look and see if can spot a leak or do a soap suds test externally on the gaskets to see if you notice anything. these old gaskets are about at the end of there serviceable life span. if you come up with any ideas about the power issues your experiencing other than fuel pump let me know.

Nicholas

Nick,
Call me re engine issues.
And....Please post some pics of the Uni, that is a pretty rare beast you have, nice boat!
The only other one I've seen in person was back in 01, it had twin Bearcat outboards on it and I bought them both but didn't take the boat.

Email me its in my profile and I have all the digrams and parts number I can send you. Cheeper than buying a book.
Mike aka pathfinderz1

Well... I replaced the waterpump today. It only took about 2 hours. The old one was pretty well deformed and hard so it was defineately due. I was talking to Bill yesterday and he said this was a thermostatically controlled temperature so i checked the thermostat and of course the thing is totally corroded and not working. I was curious what the consequences of running without the thermostat would be? I have done that with some classic cars I have worked on when we would go to a car cruise. Just improved the low speed flow. I would think that this would help with the low speed temp on this too. I

Nick, I'm no expert on the Super Seahorse, but would like to throw this out there for your consideration. Generally speaking, the removal of a thermostat is not a good idea. (I used to do it on the hot rods too, just to be perfectly honest.) Two basic reasons were explained to me, thought I'd share them with you. The thermostat not only closes to bring the engine to operating temp, but also moderates the flow of cooling water even in the open position. The engine is designed to operate at a set temp range, and running it cooler means the motor probably won't operate as efficiently. Also, if the coolant passes thru the motor too quickly, it does not have the chance to absorb as much heat, so while you've got increased volume, it's not necessarily cooling the motor more.

It probably wouldn't hurt it to run it temporarily without one, but if it were mine I'd source a new 'stat and install as soon as possible. Just my two cents worth.

I think I've got a complete t-stat assembly off one of those V4s if you need one... And yes, thermostats are needed. The motors run much cleaner and last much longer when they can operate at a controlled temperature.

Now thats one I have never figured out. Did any or your cars or hot rods ever get hot with no themostat in it?
Don't think so none of mine ever did. Any water pasing through the motor will absorb some heat. And yes your outboard will run vary cool with out a themostat in it and may not burn as clean running that cool. Hell all my old outboards don't have a thermostat in them and they were made to run on 30wt motor oil. I have heard of corbon bild up in the exhuast but never had it happen to any of mine.
Mike aka pathfinderz1

I won't argue that running with the correct thermostat is in theory a good idea. Having said that, I removed the thermostat from my 1960 Evinrude Lark 40 hp. motor about 20 years ago, since it seemed to be running too hot with the thermostat installed. ( The thermostat was new, and tested ok in a pot on my stove). I don't plan to ever reinstall a thermostat. If I were running my motor in very cold water or air temperatures, I might reconsider.
I hope you get your 75 hp. motor sorted out. A friend had a 75 hp. Johnson on his boat back around 1962, and it was a wonderfully reliable and powerful motor. It took us many hundreds of miles on memorable trips, without ever a failure. I can still hear the sound of that 4 cylinder engine, which was more like a loud hum than a roar.

+1 for your diplomacy posting alternative opinions 63M. One of THE best things about FG is the ever increasing list of discussions that present many different opinions on topics such as this.

Thank you all for your input. I am going to take her down tomorrow and give it another test. Ill let you know what happens.

Ok so I finally got it out and it didn't go so well at first. Had a bit of a timing issue, well more than a bit. As soon as I advanced the timing just a touch she ran like a top. But......when running at planing speed, about 75% throttle the fuel bowl runs out of gas after a short time. It still seems to run ok though but when I run at WOT for over a minute or so it sputters and dies. Not sure what to do now even after the new fuel pump. Any ideas?

Nick, please keep in mind my earlier disclaimer about not being familiar with this particular model, but you're still having fuel delivery problems it sounds like to me. Just a couple more thoughts come to mind:

Have you done a compression check on this motor? The crankcase pressure comes thru a hose from the crankcase (obviously) to the fuel pump. When you replaced the fuel lines earlier did this one get replaced as well? (It's a bugger getting to the end down under the motor, but it can be done.) My V4 had a new high volume fuel pump installed when I got it, but they didn't replace this hose and it did have a split in it where it pushes onto that connection.

Fuel pickup in the tank - Some have a small screen on the pickup tube, you may want to pull it and check for partial obstruction there. Also, go back over the fuel line to check for air leaks (however slight) at all the fittings. Other than that, I don't know what else to tell you to check, sorry.

Well I thought I'd post a bit of an update. I decided to repower with a Homelite for now. Not sure what to do about the other issues going on now. I think its more ignition related because one minute it gets up on plane like nothing then I throttle down and try again and it wont get up over say 2000 rpm and then dies. I looked at the coil and noticed when i pulled the wire off that its oily inside the plug area. When it warms up it does a missfire out the exhaust when i have it in the tank too. Timing maybe? But only when warm. Im at a loss. The good news is I did get the fuel issue and heat issure sorted out. Had a small crack in the pressure line from the crankcase. So as soon as I get the Homelite put back together I may try to sell this thing.....or try to figure this issue out. Who knows.

This was the pic I was going to post. Gonna have to figure this out