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Old 20-05-2014, 13:12   #16
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Re: Possible Transmission Coupling Failure?

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Originally Posted by TopherTopher View Post
...The prop shaft doesn't seem to be spinning consistently or much at all.
...something seems to be broken somewhere between the stuffing box and propshaft...

It appears to be a spray deflector, just forward of the packing gland. If so, you can use a small mirror to observe the section of shaft exposed between the coupling and packing gland. If it seems to spin normally, in forward and reverse, then the problem may be your prop mounting.
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Old 20-05-2014, 17:21   #17
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Re: Possible Transmission Coupling Failure?

Lots of suggestions above, but I'm not sure if this has come up: simple test is to start engine, put in gear while tied to dock, observe the shaft area. Check to see that the shaft (and the zinc collar attached to it) are turning at the same rate as the engine coupling flange. A pair of reference marks, one on the flange, one on the zinc will show this easily.

If they turn at the same rate, there is no slippage between coupling and shaft. Then run up the revs a bit and see if the shaft speeds up similarly. If it does, then slippage in the transmission is ruled out, and the remaining factor is the connection between prop and shaft. You will need to get into the water to check that... by leaving the transmission in gear and trying to turn the prop by hand... should not be possible.

I believe that those tests should isolate the problem.

Cheers,

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Old 20-05-2014, 18:11   #18
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Re: Possible Transmission Coupling Failure?

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Originally Posted by Jim Cate View Post
Lots of suggestions above, but I'm not sure if this has come up: simple test is to start engine, put in gear while tied to dock, observe the shaft area. Check to see that the shaft (and the zinc collar attached to it) are turning at the same rate as the engine coupling flange. A pair of reference marks, one on the flange, one on the zinc will show this easily.

If they turn at the same rate, there is no slippage between coupling and shaft. Then run up the revs a bit and see if the shaft speeds up similarly. If it does, then slippage in the transmission is ruled out, and the remaining factor is the connection between prop and shaft. You will need to get into the water to check that... by leaving the transmission in gear and trying to turn the prop by hand... should not be possible.

I believe that those tests should isolate the problem.

Cheers,

Jim
Yep, not sure where the OP went, but this is pretty easy to islolate if the transmission or something aft.
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Old 20-05-2014, 21:05   #19
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Re: Possible Transmission Coupling Failure?

Someone else might suggest a reason for the presence of the "zinc" or "Spray deflector" item between the coupler and the stuffing box. Any spray should be controled by the properly adjusted stuffing box and a zinc has no real function here. The presence of this collar might inhibit the ability to adjust the stuffing box and it certainly blocks the view of the rotation of the shaft. I don't think that I would tolerate it's presence.
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Old 21-05-2014, 08:16   #20
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Re: Possible Transmission Coupling Failure?

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Someone else might suggest a reason for the presence of the "zinc" or "Spray deflector" item between the coupler and the stuffing box. Any spray should be controled by the properly adjusted stuffing box and a zinc has no real function here. The presence of this collar might inhibit the ability to adjust the stuffing box and it certainly blocks the view of the rotation of the shaft. I don't think that I would tolerate it's presence.
Good point, so maybe adjustment for stuffing is all the way in (new stuffing needed) and this was just a way to control the spray. One still wonders about the metallic nature of the discoloration, unless there is no metal in the spray. Also, original problem of power not being transmitted to propeller.
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Old 21-05-2014, 16:07   #21
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Re: Possible Transmission Coupling Failure?

UPDATE:
The nuts on this collar were finger-tight.
I guess they came loose from the frequent shifting (attempting to pop the folding prop)

Anyway - I think the collar was spinning because it shredded the keyway.
I've got to get a replacement key, but I don't think I can fit the whole key in there, under the coupling, without hauling-out and pulling the prop-shaft, But I think I can fit a small, temporary key in there in case I need to motor en-route to a boatyard.

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