Leak or exhaust? Fix? 69 Johnson

[AJRanger]

My '69 Johnson, 55hp, seems to be leaking from behind the prop. It looks like unburned oil (judging by: http://forums.iboats.com/showthread.php?t=250519 )

The above thread identified it, but didn't say if it was an issue or not. It seems like something that ought to be fixed, right? How?

I have been working on this engine for a while and just got it to the point I trust it on the river. I ran it all day for the first time right before this leak appeared, so I am not sure if this was an existing problem or something new.

It may or may not be related, but while running back downstream at full throttle, the engine gave a little sputter and then suddenly went faster than it has ever gone before. Thoughts on that?

 

[F_R]

Re: Leak or exhaust? Fix? 69 Johnson

The last sentence: Suddenly went faster. Prior to that, it was not running on all 3 cylinders. When the third one kicked in it took off.

That could also explain the excess gas discharge. It it was pumping gas through that non-firing cylinder, it just went on out the exhaust (which is through the prop)

 

[AJRanger]

Re: Leak or exhaust? Fix? 69 Johnson

Now it won't start at all after an hour's use. It started to lug like it was under a heavy load, then speed up, then lug again. I know a fuel pump is usually the cause of engine pulse, but the pump is brand new. I took it back and exchanged it for another one, and the problem remained. I followed the fuel line and found nothing amiss. The Carb was just cleaned, so I don't think it is there, unless I got a bad gasket or something. Thoughts?

What likely caused the cylinder to fire or not fire? Spark plugs were replaced to no effect. Coil?

 

[Daviet]

Re: Leak or exhaust? Fix? 69 Johnson

Have you checked the compression and spark, if not that is where you start.