'58 18hp Johnson crank leak?

[reelfishin]

I came across an old boat today, bought it pretty right and on it was an old FD-12 motor, (18hp, circa 1958). It runs pretty decent but has an irratic idle, I do notice some fuel around the top crank seal and it has some 'noticable' play side to side in the crank. It don't knock, and the last owner was still using it regularly. (Even still has a fully functioning pressure tank). Compression is 105/100. I suppose it's seen lots of use over the years, but it still runs decent.

My question is, did these wear the top bearing or was it more common to find a worn crank? I won't be using this much, if at all, but would like to make it 100%.
The worst part is that someone camo painted it, but I suppose it was a pretty decent looking motor before that. It looks pretty clean under the cowl.
Also, should I be able to feel any play in one of these side to side? Its pretty minor but noticable if you really try to feel for side play. If not, what are the chances its just the seal?

(It was sort of a byproduct of the boat purchase, the boat was way too new for this and I have other plans for the boat. My original intent was to part this out, but it looks like it may be a viable motor yet).

 

[wbeaton]

Re: '58 18hp Johnson crank leak?

Are you sure the crank is moving and not just the magneto? It sounds more like the mag to me.

 

[tmcalavy]

Re: '58 18hp Johnson crank leak?

Can't answer you question about the seal, even though I run one of those myself on my little tinny. Great outboards, keep it and run it as an old reliable. It'll always get you home.

 

[F_R]

Re: '58 18hp Johnson crank leak?

reelfishin, you are correct on the year, it is a 1958.

Now about that bearing: If it is "noticeable" it is shot. Not just the bearing, but most likely the whole powerhead. It is a roller bearing and it rolls directly on the crankshaft. One simply cannot wear out without both wearing out. If fact they normally don't wear out at all unless water has been getting in there and has rusted, pitted, etched the hardened and polished steel surfaces. Even as old as the motor is, if you were to tear it down the bearings and crank should look like new. Except for extremely unusual circumstances, if that bearing is shot there will be others just as bad or worse. Doesn't much matter, the crank is the heart of the motor and if it is dead, the whole thing is dead.

All this goes back to the word "noticeable". Bearings cannot run "tight" tight. They need a thou or two clearance. But I doubt you are noticing such a small clearance without a dial incator.

Worn, etched, pitted roller bearings have a very distictive sound when running that any experienced outboard mechanic will recognize immediatly. Believe me, I have heard a jillion of them, it seems. The best I can describe it is like the sound of an iron wheel rolling on a track or rail.

 

[jbjennings]

Re: '58 18hp Johnson crank leak?

I have a '57 18 hp johnson and it had black burnt fuel under the flywheel. It was from a bad crank seal. You should be able to take the stator plate with the coils on it off by taking out the center coil screws and the 2 screws in the plate itself (not the pts. adj. or the condenser screws). It'll come right off but make a note of the position of everything, especially the 2 plates below the stator plate. You should be able to see the crank seal now. Put a little motor oil on the seal and put the flywheel nut on the crank and use a socket to turn the crank. It will bubble up horribly if the seal is bad. You can also try to wiggle the crank then and see how bad your play is. It's probably your stator plate wiggling like WBeaton said and not your crank, hopefully. Almost all of 'em this old wiggle some because of the constant uneven pulling of the magnet in the flywheel on the coils. Before looking at the under flywheel stuff you might double check all the seals on and behind the carb by spraying a little dab of carb cleaner around the seals while idling and seeing if the idle changes. 2 experts already checked in with you so my post is probably irrelevant, but might help a little.
I sure love the 50's OMC's, and even worn out, they'll still run for another 100 years,
JBJ

 

[samo_ott]

Re: '58 18hp Johnson crank leak?

Reelfishin, did you get the idle fixed? btw, you might be totally looking at the wrong thing. A bad idle could very well be a carb issue. Have you looked at that yet?

 

[reelfishin]

Re: '58 18hp Johnson crank leak?

Sorry for the delay, I haven't had time to get back here till now.
The play I notice was by grabbing the flywheel and moving it side to side.
There is definitely a leak at the top of the crank, I sprayed it all clean and it gets damp as soon as it runs. It don't knock or make any odd noises, it does sound different than my newer motors but it also lacks all the insulation and fiberglass cover.
If I grab hold of the flywheel and shift it side to side, I can feel some movement. I can feel the same movement in my 1969 18 hp, but not quite as much. I put it on another boat just to try it out, it pulls great and don't run bad under power. The compression increased slightly after running it a bit, I got 113/115 after running it. It's hard to tell how this was treated, it's been done over in hunter's camo. But under the cover it looks pretty clean, not pitted, corroded, or greasy, but clean copper colored paint. The carb may need some attention, I have no idea how long it sat, but the leak is a definite problem.
What I was wondering is whether I could be noticing the play simply due to the fact that the seal isn't cushioning the feel so to speak?
If it is worn that bad, it still runs pretty good. But I wouldn't want to trust it and it will most likely get parted out.
Will any of these parts on the 1958 fit any later motors? I have several later 18-25hp motors, up to say 1975 or so.
I have a 1968 18HP with a bad lower unit, would this maybe fit?

 

[samo_ott]

Re: '58 18hp Johnson crank leak?

It should fit. I think they're all interchangable. My 18hp '59 LU fit on my '66 so pretty close to what you want to do.