1970 Johnson 40hp cracked flywheel.

[broncojeff78]

He all. I just wanted to let you know the stupid thing I did today so maybe someone could not make the same mistake. I am fixing up a 1970 Johnson 40hp that is on an old MFG 14' boat. I am going thru every system on the engine as it has been sitting since 2000. One of my last things on the engine was replacing the points and coils which of course require pulling the flywheel. Im between 2 little kids, running my own business and being out of town Mon thru Fri lately its tough to find time to work on it so I guess this afternoon I was rushing a job I shouldn't have. I got the appropriate puller and some grade 8 bolts to pull the flywheel. Now I read alot about it on this forum and some say to put pressure on it and wait and some say tap it with a hammer. I didnt have much time and tapping wih a hammer didnt work so I thought I would give it a little heat.(bad idea) Once I started to gently heat it I heard some creaking suggesting that it was ready to break loose, which it did. Apprently even a little heat softens the aluminum too much and cracks developed out of the bolt holes where the grade 8 puller bolts go and now the flywheel is junk. I really had alot of pressure on the puller but it didnt budge without the heat. Once I got it off everything inside looked like new so I'm thinking I could have left it alone. Now I guess my next step is finding a flywheel.

 

[Daviet]

Re: 1970 Johnson 40hp cracked flywheel.

I don't think you are the first person to damage a flywheel on a 40hp.
Look at the top of the page in the "Top Secret File" sticky, there is a list of salvage yards there, maybe one of them can help you out with a flywheel.

 

[broncojeff78]

Re: 1970 Johnson 40hp cracked flywheel.

I forgot to mention, when I got it off I found some sort of loctite type stuff on the mating surfaces of the flywheel and crank. Do I need to put something on here when I re-install the new flywheel? BTW I was able to find a NOS flywheel for 45 bucks so I didnt make out too bad.

 

[Daviet]

Re: 1970 Johnson 40hp cracked flywheel.

No, do not put anything on the crankshaft taper, make sure the crankshaft and the mating surface of the flywheel are clean and then torque it down to the proper spec.

 

[broncojeff78]

Re: 1970 Johnson 40hp cracked flywheel.

Ok that was what I had thought before but this is the first outboard I have ever worked on in depth and wasnt 100% sure. Thanks.

 

[Daviet]

Re: 1970 Johnson 40hp cracked flywheel.

Good luck with your engine, it should give you manys hours of boating pleasure.