prop problems again!!

[iggyw1]

O.K. guys, I replaced my prop on my Evinrude 1962 40 h.p. model #35933 motor due to a spun hub. This motor has the shear pin prop with the plastic (nylon) prop nut on the end of it covering the prop shear pin and the prop shaft, with the cotter pin thru it and also thru the shaft. When I first put the new prop on the motor, the hub was flush with the inside of the prop housing. It is now working it's way deeper and deeper into the prop housing and sticking out of the prop more and more on the outside of it. I am seeing skinny rubber fragments on the inside when I remove the prop. Seems like this prop is ready to be a spun hub too! I only ran the motor three times since replacing the prop, and not in any weeds. What could be the cause of the spun hubs??

I noticed in my Seloc manual that there is some type of washer under the prop, between the prop and the motor bottom unit gear housing "ON CERTAIN MODELS". There is no washer and never has been a washer there in the three years that I owned this motor. Could a lack of this washer which "MAY " belong in place be causing the problem I am having? What kind of washer is it that should be under the prop?
Thanks for your input!

 

[steelespike]

Re: prop problems again!!

Was the prop new?
The motor is a pin drive and the pin positions the prop so no thrust washer.
From your description it does appear the hub could be failing.
If its a used prop its not unusual for a hub to fail simply from age.

 

[iggyw1]

Re: prop problems again!!

Yes, the prop was a new one that I purchased from iboats. I just took it off again and inspected it and there was a small 'sliver' of rubber inside the housing where the hub is sitting. It is no longer flush with the prop housing. Wondering if I got a bad prop? Maybe it just tightened up as it seems to me that it can not go into the prop housing any deeper looking at it from the back side. It appears that the prop housing is slightly tapered and the hub cannot get any deeper at this point. Just worried about spinning the prop when I'm out a few miles off shore!

EDIT: The washer in my manual on "some" models (does not say which ones) looks like just a flat washer. There are other models that do have a thrust washer, and they are indicated as such in the manual and they look different too. The washer they are showing in "some" models looks like just a flat , thin washer. MAYBE mine is one of the models that needs this washer?? You think the book would indicate which models need the washer, but it sure does not spell it out (unless I am missing something in a different chapter of the manual somewhere). But I still do not see how the washer would prevent what is going on with my prop.

 

[Texasmark]

Re: prop problems again!!

The thrust washers are used with splined shafts and the props are locked against it with the prop nut. The shaft is tapered as is the thrust washer and the washer is pushed against the taper on the shaft by the prop for the torque setting. No slop between the prop and the prop shaft.

Back in the days of the drive pin, as Steel said, the pin positions the prop on the shaft and there is some slop in the prop vs the prop shaft. The plastic cover and cotter pin just flop around. But that's the way OMC did it for 10's of years, as did others, and it took Merc's splined prop shaft patent to run out before they changed.

As I recall the Rude Triumph 55 hp loop charged completely new design in (1968 as I recall) was the first with the splined shaft along with their completely redesigned lower unit.....very similar to what Merc had been running for years, including their thru prop exhaust....forget what Johnnyrude called theirs.

I agree that you shouldn't see pieces of rubber coming out, nor the rubber hub deforming. No offense to the site, but just because it's new doesn't necessarily mean it was "just" built. Some things, especially props for vintage engines could sit on the shelf for a long time.

If worried about going offshore, I'd buy a backup and have a spare...prop, drive pins, cotters and caps.

On the engines with the optional washer, have no idea what that looks like, nor it's function.

Mark