1980 70 HP lower crankshaft seal question

[sbklf]

I am putting a different powerhead on my motor and thought I would replace the lower crankshaft seal and o-ring while it is off. I took the bearing plate off and the seal appears to be installed the wrong way. The way I thought seals were designed is that the cupped side faces what you were trying to seal in and the flat side out to the elements so to speak. The seal is installed with the cup side out. The only thing I can figure is that it was replaced and installed the wrong way or the case operates in a vacuum and the seal keeps water and stuff out instead of fuel/lubrication in. Here are some pictures of the seal. Thanks, Kevin

 

[F_R]

Re: 1980 70 HP lower crankshaft seal question

I am putting a different powerhead on my motor and thought I would replace the lower crankshaft seal and o-ring while it is off. I took the bearing plate off and the seal appears to be installed the wrong way. The way I thought seals were designed is that the cupped side faces what you were trying to seal in and the flat side out to the elements so to speak. The seal is installed with the cup side out. The only thing I can figure is that it was replaced and installed the wrong way or the case operates in a vacuum and the seal keeps water and stuff out instead of fuel/lubrication in. Here are some pictures of the seal. Thanks, Kevin

I just checked the book and the seal is installed correctly. The lip faces down. I reckon they are more concerned with water gettng in than oil getting out. BTW, the case operates in both a pressure and vacuum, depending on whether the piston is on the up or down stroke.

 

[sbklf]

Re: 1980 70 HP lower crankshaft seal question

Thank you so much. Which book do you have? My Clymer's does not say or show anything. Kevin

 

[F_R]

Re: 1980 70 HP lower crankshaft seal question

Thank you so much. Which book do you have? My Clymer's does not say or show anything. Kevin

Actually, neither does the factory manual. I took a peek at a slightly newer motor's parts list. They show the seal orientations on the newer parts lists.