Fitup problem with new alpha prop...

[gixxerjim]

I bought a 21P prop to use as my primary prop and relegated my 19P prop to backup status. I bought the 21P from a guy online who said it was off an alpha. I brought my current prop with me to compare to make sure...

The teeth qty and shaft size are identical, and all other details looked the same to the naked eye. When I put it on my propeller shaft, however, it made a light scraping sound when spun by hand, like it was contacting the lower unit housing instead of seating against the prop or bearing race properly.

This is my first real boat (18' Sea Ray, 1988) so I have much to learn. Is it possible this prop is not for an alpha I? Everything matches up except it makes that scuffing sound every rotation. I thought of cutting an 18gauge (0.048in thick) stainless steel washer and adding it between the prop and the lower unit and retesting...

Any input would be appreciated.

 

[gixxerjim]

Re: Fitup problem with new alpha prop...

The new prop is #48 5842A4 21P.

It seems this was for the old Mercruiser 1 drive. I read a post here on iboats that props from some old 1 drives will fit alpha drives.

Like I said earlier the prop fits the shaft etc, just seems like it needs to be shifted slightly backward on it.

Anybody have any information or experience on this?

 

[danfrompgh]

Re: Fitup problem with new alpha prop...

Are you sure the thrust washer is not still sitting in the old prop?

 

[gixxerjim]

Re: Fitup problem with new alpha prop...

No, I pulled it and put it in the new one. The scuffing sound comes once a revolution, maybe 45^ of the revolution there is a light scufffing sound...

 

[danfrompgh]

Re: Fitup problem with new alpha prop...

If the thrust washer is in place there are not many options. Possible bent prop shaft or bad prop design. Hopefully one of the older salts will chime in.

 

[Dhadley]

Re: Fitup problem with new alpha prop...

It may just need a slightly thicker thrust washer. However, if it makes the sound once a rev then the hub may not be seated square in the bore. Or the propshaft could be bent. Check the propshaft first.

 

[gixxerjim]

Re: Fitup problem with new alpha prop...

My 19P spins true no problem so I think I will just have to look into the slightly thicker thrust washer for the 21P.

Thanks for your input!