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Propeller shaft seals orientation

Garygin

Garygin

Regular Contributor
I’m rebuilding my complete lower drive. I have a service manual that shows the two seals on the propeller shaft. It says “ note orientation “. I’ve been a machinist for over 50 years and I’ll tell you the image they show leaves a lot to be desired. Can someone please tell me the correct way to install them.
Thanks for your help.
 
Hi,
I assume that you have a propshaft that takes 2 single lip seals, one atop the other. I believe that the original intent was to have the inner seal installed with the shell facing outward and the the exterior shell facing inward. There has been much discussion about how they are installed and I do think that configuration would work.

However, my outboard has just one double lipped seal for the propshaft and both lips are configured the same. The seal assembly is installed with the shell facing outward.

Thinking of it logically, the single lip is designed to contain liquid and should expand and press against the shaft as heat and pressure builds internally.

As a result, it seems to make the most sense to install the seals with both shells facing outward since there is no external pressure or heat on the exterior of the case.

This is just my opinion and others may disagree.

Good luck.
 
If I understand you correctly the inner seal is meant to keep gear oil in , therefore the seal should be installed with the solid surface outward. The outer seal should be installed the opposite with the solid surface of the seal inward to prevent water from entering the case. Does that make sense to you? Thanks for your help. Very much appreciated.
 
Hi,

Sorry, no.

What I suggest is that BOTH seals be installed with the solid surface facing outward.

I apologize for the confusion.
 
Any that I have seen have been have one facing in and the other facing out.... anothern problen area on high hr lower units is the shifter shaft seal and shift shaft wear.
 
FYI. After thoroughly going over the image in the service manual and looking at it , I have come to the conclusion that the seals go in with the inner one solid face out and the outer one with the solid face in. Why can’t they put it in writing and explain it in more detail.
Thanks again for your help.
 
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