I am a boating newbie and the new owner of a 1970-something Johnson 40hp
outboard. I have had it out for maybe 8 hours so far without any problems.
The other day it started acting up. When I push the throttle forward, the
boat moves, but then the engine just rev's up and the boat doesn't go
anywhere. The closest comparison I can make is that it seems like a clutch
is slipping.

I'd like to repair the engine myself. Where should I start looking?

Thanks for any info,

Pyro Dave.

P. Dave...

The prop hub is slipping. The shear pin on that engine actually connects
the prop shaft to a separate shaft/steel hub which is pressed into a rubber
hub/bushing which is then pressed into the propeller housing. It all looks
like one piece as mounted on the engine, but when you take the plastic prop
nut off with the cotter pin, and then slide the shear pin out and prop off,
it will become obvious on the back side (fore facing) as to the
construction.

Get a new hub pressed in at a prop shop, and get a spare prop too.

Good Luck!

Rob
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"Booms" wrote in message
news:Rj27b.9866$J6.639@pd7tw3no...
I am a boating newbie and the new owner of a 1970-something Johnson 40hp
outboard. I have had it out for maybe 8 hours so far without any
problems.
The other day it started acting up. When I push the throttle forward, the
boat moves, but then the engine just rev's up and the boat doesn't go
anywhere. The closest comparison I can make is that it seems like a
clutch
is slipping.

I'd like to repair the engine myself. Where should I start looking?

Thanks for any info,

Pyro Dave.

It's possible the shift linkage is not fully engaging when you shift into
forward gear. Does your reverse work ok? If reverse works and forward does
not, it's the linkage. If both don't work, it could be the rubber spline on
the prop or still possibly linkage but less likely.

Reverse works. Forward works too, except when I increase the throttle. I
pulled the prop off and it is not splined. It has a pin that holds the prop
in position on the smooth shaft. There is no rubber hub, but there is what
looks like a bronze one. I don't think there is any way for the prop to
slip on the shaft, being that is held on by a steel pin through the whole
thing. Is there a shaft coupler that could possibly be broken?

Thanks.


"AKPBrown" wrote in message
...
It's possible the shift linkage is not fully engaging when you shift into
forward gear. Does your reverse work ok? If reverse works and forward
does
not, it's the linkage. If both don't work, it could be the rubber spline
on
the prop or still possibly linkage but less likely.

On Wed, 10 Sep 2003 15:51:47 GMT, "Booms"
wrote:

Reverse works. Forward works too, except when I increase the throttle. I
pulled the prop off and it is not splined. It has a pin that holds the prop
in position on the smooth shaft. There is no rubber hub, but there is what
looks like a bronze one. I don't think there is any way for the prop to
slip on the shaft, being that is held on by a steel pin through the whole
thing. Is there a shaft coupler that could possibly be broken?

Thanks.

It could be that the "dogs" on the forward gear are worn, and
dis-engage under load. If it's not the prop (remember, there is much
less load on a prop in reverse than at WOT) I would buy a manual and
drop and split the lower unit and inspect all gears.