Shift shaft seal lip up or down?

[Rick Stephens]

Going through a recently purchased GenII leg. Started with a pressure test since there was oil around the shift shaft and teensy coating on the water pump housing (different source, obviously). Air leaks around the shift shaft unless the shaft and rubber sleeve are pressed firmly down onto seal. The seal lips have some minor feathers of damage hanging off it, so it's gotta go.

Question is: the lip on the seal and the lip spring, are face up towards water and outwards from the shift shaft bushing/oil side, is this correct?


Thanks!

Rick

 

[flipbro]

Rick I believe that is correct as thst area has water around it at all times .

 

[Rick Stephens]

Thanks

Merc manuals don't state anything and I figured better to ask.
Won't hold much air during pressure testing :boom:

 

[PeterB26]

In general the lips on seals face the fluid you are sealing in.

It sounds like you are talking about the lower shift shaft in a Gen 2 drive?

The lower shift shaft seals here are best renewed by replacing the whole plastic assembly with the new seals pre-installed. You will also get new O-rings for under the plastic seal carrier. You will NOT get the new rubber washer that goes on the shift shaft atop the seal carrier nor will you get the e-ring that goes below it. A few cents more gets you both those things. Generally you don't need a new e-ring because this one lives in drive oil, but if you damaged it or dropped it you sure would be happy you spent the few pennies for a spare.

The upper shift shaft that goes through the exhaust cavity on the bell housing into the U-joint bellows also has seals. These are shown in the manual, though not too clearly, as lips facing up. This seems backward to me as what you are sealing is the water in exhaust cavity from getting into the u-joint bellows... nevertheless the manual shows these seals both installed lips up, and that is the way my old ones came from the factory. Maybe someone here knows why?

In other places Merc uses two seals back-to-back. Usually they are done this way to seal oil on one side and water on the other. When installed like this the void between the seals would run "dry" unless you packed it with grease as you installed the seals. If allowed to run dry the seals will fail very quickly.