Hi again Duggie.. perhaps its my naivety in not being a mechanic.. but I found it very easy to replace the seal in my Mariner 3.3HP outboard. Checking the list diagram for parts.. your 9.8 outboard gear box is almost identical to the Mariner (See below diagrams)
Tohatsu diagram 9.8 I got from net ..you want to replace part 22-4 which is the oil seal..(its just a rubber type washer with a spring embedded in it so it grips the shaft) also order and replace the O ring part 22-3 which is another seal you disturb opening the gearbox
Mariner 3.3HP diagram for comparison purpose only.. looks very similar to me..but as mentioned Im not a mechanic ..so could be wrong in that assumption ?
How easy is it to replace ?
Undo the two bolts that you see in the photo you posted.. remove the end housing by breaking the O ring seal with a twisting motion..it then slides out. Hey..then you are in the gearbox..can just lift the prop shaft and its gear / clutch straight out. Yup..its as easy as that.
However to replace the seal. I had to remove the ball race .. part 22-2. My workshop manual recommends a special tool to remove it. I have little more than spanners..screwdrivers and a hammer..but found it came off no problem with a drift from the hammer
When my gear box oil turned milky .. I wanted to open the gearbox to check components ..and ensure they were all clean.. its easy to do. Initially I though the ball race would cause me problems..so I though..get the shaft out..take it to Clyde Outboards and see if they will order the parts and remove the bearing for me. Because I found it easy getting the bearing off ..I just asked them to order the parts..which they did.
Im my manual it recommends renewing the bearing when replacing the seal. I asked Clyde Outboards to order that part too..but they had difficulty getting it..but also told me it was not necessary to replace it.
I have done hundreds of hours on that replaced seal..which I did myself. I may have done something wrong..but the OB didnít care lol. What you do is your choice.. be be rest assured..its not a difficult job..nor should it be expensive if you donít fancy doing it yourself ?
Its quicker doing it that writing about or even trying to pressure test .. its a very small and simple gearbox with a basic clutch that is easy to put back together.If you want the instructions for the 3.3 Mariner..I can happily send them when I return from adventures.
If there is a mechanic that sees any flaws in my description..please highlight it for the OP.. as mentioned..Im not an expert..only giving my personal experience