Johnson 1962 75hp CLUNK!

[daveydb]

I would first like to thank everyone that has been helping me with the problems that have had up to this point with this engine. I took it out yesterday and it started up, it still doesn't go in reverse but we tried out forward and couldn't get it to engage well. If we open the little cover on the motor, it gains a little bit of speed, but if we take the cover completely off, it runs like a top. It was pretty amazing but it seems like I have an air flow problem. There isn't an air filter that I know of so any ideas on what may be doing that.

My second problem is that we were running it at about 15 mph and it was doing really well and then all the sudden there was a loud clunk and the engine died. I could start it if I was in neutral and it started right up but as soon as I put it in gear it would make a quieter clunk and die. We pulled it out and we can still turn the prop by hand. Drained the lower unit oil and I couldn't see or feel any metal in it. The lower unit has a small leak, but the oil actually wasn't very milky. I am planning on pulling the lower unit apart but I was wondering if I could get some direction as to what the problem may be. It sounds like it could be pretty bad but I don't know.

Thanks again for all of the help. Oh, the pressure testing was off when we tested it last and now the cylinder pressure reads 80, which is quite a bit better than 15 as I had said on a previous thread.

 

[ezeke]

Re: Johnson 1962 75hp CLUNK!

If the motor dies when the cover is on, not when off, your exhaust is probably running back into the engine compartment.

Do a new compression test and let us know what each cylinder is reading.

 

[F_R]

Re: Johnson 1962 75hp CLUNK!

There is a foam rubber seal on top of the water pump. If you leave that seal out, it won't run with the hood on.

Can't predict what the gear problem will turn out to be.

 

[Evinrude Boater]

Re: Johnson 1962 75hp CLUNK!

aIs this an electric shift model?
FR, I don't remember foam seal on the water pump when I did mine. Are you referring to the foam seal around the outside of the exhaust tube?

 

[F_R]

Re: Johnson 1962 75hp CLUNK!

No. Do you remember the cover plate on top, of the water pump? The seal goes on top of that cover plate. Part number 305762.

 

[daveydb]

Re: Johnson 1962 75hp CLUNK!

I don't remember seeing a foam seal on top of the water pump. I do remember a foam seal somewhere but I don't think it was on top of the pump. The engine would still run with the cover on, it just wouldn't run very well. When we took the cover off, I could see some exhaust around the engine but didn't think much of it. I guess I should have looked to see where it was coming from. Is there a seal around the exhaust outlet?

My dad has the boat and is going to take off the lower unit and take it apart on Tuesday. If we do find something in the gears that needs to be replaced, does anyone know where I could get some used parts. I have looked around to see if there is a lower unit online but have not found anything. Thanks

 

[Evinrude Boater]

Re: Johnson 1962 75hp CLUNK!

FR, I see it in the '68 parts diagrams on BRP. I must have put mine back in. It was four years ago then it took me 2 years to repair my boat and get it back in the water.