I have 2 motors 1955 QD-16 10hp Johnson and a 1957 FD-11 18hp Johnson, the 10hp has been a good running engine since my uncle got it new in '55. The lower obtained a freeze crack in it and was repaired (JBWELD) about 10yrs ago, but now it has begun to jump out of gear the local old outboard guy said I needed to find a new lu. I found the lower unit but the old outboard guy has since went to the great lake in the sky or Florida 
<br /><br />I have pulled the lower gearcase unit from the 18hp and it fits perfectly on the 10hp, engine the RED&GREEN give it a xmas look. My question is there only appeared to be 2 diferances between the lower units. <br /><br />1. the end of the drive shaft has a hole in the end on the 18hp. Will this matter ?<br /><br />2. the prop the one on the 18hp is smaller, why is that ( would it spin faster and blow the 10hp ?)<br /><br />the other observation I made is that the inside of the lower unit of the 18hp appeared to covered with coat of grime from years of storage and the gear case was empty, dry infact, a little white powder around lower drain plug. Rubber "O" ring from the drive shaft was found inside but broken, didnt seem to be melted. <br /><br />The 18hp does seem to have compression and spark but its missin the recoil (found it in an estate sale and I dont know why it was stripped of recoil and bonnet), so I decided to make the 10hp run again first.
<br /><br />I have pulled the lower gearcase unit from the 18hp and it fits perfectly on the 10hp, engine the RED&GREEN give it a xmas look. My question is there only appeared to be 2 diferances between the lower units. <br /><br />1. the end of the drive shaft has a hole in the end on the 18hp. Will this matter ?<br /><br />2. the prop the one on the 18hp is smaller, why is that ( would it spin faster and blow the 10hp ?)<br /><br />the other observation I made is that the inside of the lower unit of the 18hp appeared to covered with coat of grime from years of storage and the gear case was empty, dry infact, a little white powder around lower drain plug. Rubber "O" ring from the drive shaft was found inside but broken, didnt seem to be melted. <br /><br />The 18hp does seem to have compression and spark but its missin the recoil (found it in an estate sale and I dont know why it was stripped of recoil and bonnet), so I decided to make the 10hp run again first.