On Aug 11, 9:47*pm, TJ wrote:
This is a long post, but bear with me, I will eventually get to the
point. There's just a lot of background to fill you in on.

I have a '64 9.5 HP Johnson outboard that gets used heavily on a 14-ft.
aluminum boat during a one week vacation each year on the St. Lawrence
Seaway. The rest of the time it sits idle, hanging on a stand or on a
wall, waiting for my next fishing opportunity. I originally got it for
free in 1986 from my sister-in-law's father, with a cracked block. By
the time I was done with her, I'd purchased a used block, one new piston
and rings, new gaskets, and a new crankshaft. It ran like a top, often
starting on the third or fourth pull when I got it out of storage, and
almost always on the first one until I put it back in storage. All it
ever needed was a periodic changing of the lower unit oil, and some
points maintenance.

Then came last year, and the honeymoon was over. It was my own fault,
too. One day while trying to launch by myself on a rather windy day, the
wind blew me back onto some rocks before I could do anything about it.
That tore up the rubber shock bushing in the prop. Naturally, the local
OMC dealer, about an hour away, was the only place to get one. According
to a book I have, the original prop was an 8 1/8 x 8 inch. All the
dealer had that would fit was an 8 1/4 x 9 inch. It was either that or
ruin vacation, so I bought it.

But that's not all that happened. I put the new prop on and it seemed to
work ok, despite being "bigger" than the original, but it wasn't really
the kind of day when one can test performance. The next day I was out
fishing with my mother, when the water pump impeller decided to give up.
It was at the most inconvenient time, too (Is there a GOOD time for
it???) - when I had to keep running it to get out of the way of
God-knows-how-many-tons of freighter. (Hey, there's nice smallmouths in
that shipping channel, but you just don't argue with one of those guys.)
I got out of the way, but I had to run the ol' Johnson until the pistons
seized to do it.

That made me physically ill. I was sure the ol' girl was a goner, but
after being towed in, allowing it to cool, checking things like the
points and compression, I tried it and it started! Ran nice and smooth,
too - for what little time I let it. Then it was back off, pull the
lower unit apart, and another two-hour round trip to the OMC dealer for
an impeller. I put it back together and ran it the rest of the vacation
on our second boat - the one my mother *doesn't* use. (Trust me - I
didn't want any more breakdowns with her in the boat.) It ran fine once
it started, but now it would take at least three or four pulls to start
it every time, and sometimes you had to choke it in the middle of the
day - unheard of before. Didn't quite have the zip it had before, either
- but I put most of that to the different boat. I was just so overjoyed
that it even ran that I wasn't about to complain.

Then came this year. When I brought it out of storage, it took 12-15
pulls to get it to start the first time. Every time thereafter it took
at least three. The power wasn't there, either. It was only about 3/4 of
what it was before. It still ran smoothly, though, and if I hadn't known
what it was capable of, I might not have thought anything was wrong -
until the last day. On that one, it started misfiring, and it ran like
it was half a motor.

So I'm thinking some major work is in order this winter. I suspect a
modest crankcase leak. I'm considering new rings, head gasket, and
crankshaft seals. New plug wires probably wouldn't be a bad idea,
either. They're still the originals. New plugs, too - those plugs are
the ones that went through the heat stroke. (I think that last day
misfiring could well be a plug going bad.) I toyed with the idea of new
bearings, but I think that if they were bad that would have shown up
catastrophically during this year's vacation.

I have two questions. Is there anything else I should be looking at?
And, how much of the poorer performance could be attributed to the
"bigger" prop? (meaning, should I buy one closer to original specs?)

TJ

Don't knwo about the prop, but it shouldn't make that much of a
difference I wouldn't think. but then again it's only 9.5 hp. and it
could make it suffer a little, but I really don't think so. If you
still ahve the old prop, you can probably have it rebuilt. There'sw
lots of good specialy shops that do that kind of work for less than
buying a new prop. But still i wouldn't think that size prop would be
expensive new.

concerning crank case leakage, you're probably correct. maybe a score
in a cylinder and piston. But also if you got it hot enough to lock,
it's possible your crank seals are damaged. I dont' know that for a
fact, but I'm kind of familiar with bad seals on old 2 cycle
motorcycles and an old lawnboy mower (also AMC).

Thaks all I can say, besides "good luck"