importance of gear case lower seal?

[nola mike]

After deciding to remove my noisy lower unit, I changed the impeller on the other drive. While in there i noticed the mangled remains of the drive shaft seal. Reading through some threads it was unclear how important this seal is. I put the drive together and ran it this weekend. Probably about 2-3 hours and 50 miles. At the end of the weekend, the gear oil looked perfect. I had planned on getting the seal and replacing asap, but now I'm thinking about waiting...

 

[nola mike]

Any thoughts? Another 40 miles, 3 hours, 2 days moored, oil still pristine

 

[kenny nunez]

That seal protects the upper sealing surface which is on the lower gear in the upper gear case. That surface is not stainless and will rust then not hold oil which causes the gear set to run dry and self destruct.

 

[fhhuber]

Eventually it will replace the gearcase oil with water...
Then your gears rust and self destruct from lack of lubrication.