Please Help on a '55 Seahorse 25hp

[greatoutdoors]

A motor I just picked up is giving me some problems. It will start, run for a few seconds then die out. I removed the carb, cleaned it spotless, reassembled with new gaskets, and it does the same thing. It's getting fuel in the bowl, and all my lines are good. I also changed the plugs. Seems to run nicely for the few seconds it will stay running. What is wrong with this thing???

 

[tashasdaddy]

Re: Please Help on a '55 Seahorse 25hp

could be carb adjustments, coils, points, condensor, suggest you do some reading here. >> http://forums.iboats.com/showthread.php?t=299680

 

[Chinewalker]

Re: Please Help on a '55 Seahorse 25hp

Do you have the correct dual line gas tank? Is the tank cap closed? Is it properly priming? Are you using fresh gas & oil mixed at 24:1?

Do you have good, hot spark in both cylinders? Compression checked? Correct J4C or J6C Champion plugs?

 

[greatoutdoors]

Re: Please Help on a '55 Seahorse 25hp

Do you have the correct dual line gas tank? Is the tank cap closed? Is it properly priming? Are you using fresh gas & oil mixed at 24:1?

Do you have good, hot spark in both cylinders? Compression checked? Correct J4C or J6C Champion plugs?

Yes to all, except I need to test the spark. I'm leaning towards it needing new coils.

 

[greatoutdoors]

Re: Please Help on a '55 Seahorse 25hp

What is the mechanism next to the carb on the right which has a rubber line that runs from it to the engine block? I took it apart and there is a spring inside.

 

[F_R]

Re: Please Help on a '55 Seahorse 25hp

What is the mechanism next to the carb on the right which has a rubber line that runs from it to the engine block? I took it apart and there is a spring inside.

That is the vacuum cut-out switch. It keeps the motor from revving way out of control in neutral or if you break a shear pin. Without that part, you can't shut it off when that happens. Unless it is in a runaway mode, it doesn't do a dang thing but go along for the ride.

Chances are about 95% or better that you have bad coils. But you already guessed that, didn't you?

 

[greatoutdoors]

Re: Please Help on a '55 Seahorse 25hp

Ok. Thanks for the input guys. How hard is it to change the coils and how long should it take? Should I attempt it? I called my local marina and they don't want to touch it. Said it's too old. I have read the top secret file on it and I am mechanically inclined, but is there anything I need to know that the file doesn't mention? Anyone done it on this particular model before? I want to get this baby running and replace the '53 Ev Fastwin 15 hp I have now. It runs perfect but doesn't plane my boat--but this one should. Thanks again for the help.

 

[F_R]

Re: Please Help on a '55 Seahorse 25hp

Ok. Thanks for the input guys. How hard is it to change the coils and how long should it take? Should I attempt it? I called my local marina and they don't want to touch it. Said it's too old. I have read the top secret file on it and I am mechanically inclined, but is there anything I need to know that the file doesn't mention? Anyone done it on this particular model before? I want to get this baby running and replace the '53 Ev Fastwin 15 hp I have now. It runs perfect but doesn't plane my boat--but this one should. Thanks again for the help.

Oh, I've done a few--thousand. You have to pull the flywheel. You need a puller for that. A harmonic balancer puller will work. Use only Grade-8 bolts with it. Screw them into the flywheel 7/16", no more and no less. Then give it heck--you have to pull hard to get it to pop loose. DO NOT use a puller that grabs the outside of the flywheel.

Install the new coils so their laminated cores are flush with the machined edge of the posts where they sit. Check the points while you are in there. Greasy don't get it. Neither does worn out contacts. Gap them to .020" at their widest opening.

Most important thing you can read today--when reinstalling the flywheel, the crankshaft and flywheel tapers Must be clean and dry. You MUST use a torque wrench to tighten the nut to 60-65 ft. lbs. Ignore this and destroy your motor.