55 HP Johnson having trouble, HELP!

[Wask]

I have a 55HP Johnson that is seized up. The flywheel turns almost all the way around, but wont turn in a complete circle.<br /><br />What could it be? I have the shop manual and I think I can do the work to it, but I dont know how to diagnose the problem.<br /><br />Any help is greatly appreciated<br /><br />Thanks<br />matt wask21@yahoo.com

 

[JB]

Re: 55 HP Johnson having trouble, HELP!

You have probably broken a rod or a piston, Wask. Other possibilities are even worse.<br /><br />Pull the spark plugs, run a piece of wire in each cylinder while you turn the flywheel. Each piston should move when the flywheel moves. If not, that's where something broke. Pull the head and hope the block isn't broken, too. You might get off with a new piston and/or rod.<br /><br />You didn't say how old your engine is, but you might want to question whether it would be cheaper to replace than fix.<br /><br />Sorry I can't be more optimistic. <br /><br />JB

 

[Wask]

Re: 55 HP Johnson having trouble, HELP!

JB - it is a 1978<br /><br />How can you tell if a rod is broke? I am in the process of removing the power head now, I can see that both pistons actually are moving.<br /><br />thanks <br /><br />Matt<br />wask21@yahoo.com

 

[JB]

Re: 55 HP Johnson having trouble, HELP!

That is good news, Matt. If a rod were broken one of them would be stationary. Once you have the cylinder head off you should have a better idea.<br /><br />Good luck.<br />JB

 

[Wask]

Re: 55 HP Johnson having trouble, HELP!

Good, Im glad to hear that. <br /><br />What do I need to take off, do I follow instructions for removing the power head or can I skip to disassumbling the power head? Do I need to remove all of the carbureators and stuff?<br /><br />Thanks a lot for your help<br /><br />Matt<br />wask21@yahoo.com

 

[JB]

Re: 55 HP Johnson having trouble, HELP!

For starters, Matt, remove the cylinder head, the carbs and the reed plates. Then you will be able to see the heart of the engine. . . the crankshaft,rods and pistons, and can determine just what is not doing what it should. You will probably need to remove the power head from the lower end later, but I think diagnosis is your first priority.<br /><br />Good luck.<br />JB

 

[hondon]

Re: 55 HP Johnson having trouble, HELP!

Slow down guys .Before you start pulling powerhead lets make sure you dont have a gearcase that is seized.Drop the gearcase before going any further.

 

[Wask]

Re: 55 HP Johnson having trouble, HELP!

Woah! How do you drop the gearcase??<br /><br />mw

 

[hondon]

Re: 55 HP Johnson having trouble, HELP!

Before we even get into that lets check the condition of your gear oil. Drain the gearcase into a pan ,two flathead screws,one near the front of the propshaft bullet the other above the cavitation plate on the same side of the case.Is this all water?Is this gray and full of metal?When you spin the prop in neutral does it spin freely or make any noise?Any rust in that gearoil or is it clean brown and clear?Would also like to know if this is an electric shift or mech.shift.