I think I have a problem, and I'm not sure what to call it

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possom813

Seaman
Joined
Jun 22, 2010
Messages
67
I've finally gotten everything tweaked and working right on my boat, just waiting for my 5 terminal ignition to get here.

I took the boat out today with the family just to cruise around and do a little fishing.

The boat is running well, the only issue that I've found is when I try to go fast. It goes fine and dandy about 3/4 throttle.

If you try to go faster it seems like it kicks out of gear.

It's a 1970 Johnson 40hp electromatic,selectric, whatever the proper term is.

The only thing that I can think of is that the shifter may have an exposed wire in it or something that is touching when the lever is moved that far forward.

It goes fine for a while and then it will do this, running at a comfortable cruising speed the motor winds up and the boat slows down, like there is no load on the motor, pull the lever back about an inch and everything works again like it's supposed to.

Any other ideas on what this could be before I take the controls apart?
 
lindy46

lindy46

Captain
Joined
Nov 27, 2008
Messages
3,886
Re: I think I have a problem, and I'm not sure what to call it

Could be a spun hub on the prop. Works ok at lower speeds, but hub gives way at higher speeds. Draw a line with permanent Magic Marker across hub and prop. Run the motor to repeat the problem, then look at the marks and see if they've moved. If yes, the hub is slipping.
 
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yoster

Petty Officer 2nd Class
Joined
Aug 19, 2010
Messages
117
Re: I think I have a problem, and I'm not sure what to call it

Ditto on what Lindy said.

If it was actually kicking into neutral, then when you back it off kicking back into gear, you would feel (and hear) a HUGE KA-CHUNK at those RPM's as you back the throttle to 3/4 and it re-enters gear. If on the other hand it's just revving up and as you back down, the rpm's ease back down and speed picks up, it's definitely a hub spinning.
 
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tx1961whaler

Vice Admiral
Joined
May 31, 2008
Messages
5,197
Re: I think I have a problem, and I'm not sure what to call it

Confirm whether or not it is a spun hub, and pray that it is.
If you come back and say that it is not a spun hub, then we'll tell you what expensive part is broken in the electric shift lower unit.
No use borrowing worry until you eliminate the prop.
 
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Daviet

Fleet Admiral
Joined
Sep 24, 2008
Messages
8,958
Re: I think I have a problem, and I'm not sure what to call it

I have in the past seen a spring slip on a hub causing a slip. Is there any metal particles in the lower unit oil?
 
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possom813

Seaman
Joined
Jun 22, 2010
Messages
67
Re: I think I have a problem, and I'm not sure what to call it

alright fellas, what exactly is the hub that can spin? I'm not sure what I'm looking for and nothing is called 'hub' in the diagram.
 
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tx1961whaler

Vice Admiral
Joined
May 31, 2008
Messages
5,197
Re: I think I have a problem, and I'm not sure what to call it

The propeller is actually 3 pieces: the center hub (bronze?), a very thin rubber bushing, and the aluminum blades. The center hub is bonded to the outside blade assembly by the rubber bushing. It is all pressed together, and you really can't see the rubber part at all. You won't find the bushing in any diagram, since the propeller is sold as one unit. A propeller shop can disassemble the propeller and press in a new bushing, or you can buy a new propeller.
 
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possom813

Seaman
Joined
Jun 22, 2010
Messages
67
Re: I think I have a problem, and I'm not sure what to call it

Woohoo! I put on a different prop(because I have 5 or 6 laying around for this model) and went fishing today. No real problems and finally got it on a plane.

It did a freespin thing once, but I think I popped out of the water after a big wave because there were no more issues after that one.
 
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