78 Johnson 115 water pump kit ?: unidentified oring / is Factory diagram exact?

[grossgary]

This is my first work on a lower unit, so I'm inexperienced with boats with a fair amount of auto experience/heads/valves/trans/swaps.

I bought a sierra water pump kit for a Johnson 115 (​115ML78C) and the factory diagram shows no oring between the impeller and the impeller plate below it on the gear case. I mean it shows some orings up higher - maybe they're out of order? Here's the factory diagram:

http://shop2.evinrude.com/Index.aspx?s1=4pt7hqh6j1dccp3u8fcpju8pm3&catalog_id=0&siteid=1

The kit also has an oring that none of the 3 water pumps/cases I've torn apart have shown. I could post a picture but I doubt they're that recognizable.
I've seen that with engine gasket sets for rebuilds...same here?

And I'm not too surrised about this but the part numbers I could find in the kit don't correlate with those on the Johnson website link above - I mean a few do, but the rest don't. Parts cross referencing and updated part numbers are normal.

 

[F_R]

There is no o-ring between the impeller and plate. But there is one between the pump housing and plate, 321120. Yes, kits sometimes have parts that are used on other models.

 

[Faztbullet]

All new aftermarket and Bomb V4/V6 impellers come with a relieved area around hub and the o-ring fits there...as assembled would be:Gasket ,plate,new-o-ring,impeller and housing.

 

[interalian]

Bomb=OEM thanks to spellcheck?

And that o-ring under the impeller is a good way to hold the drive wedge in place - put it over the wedge, then lower the impeller over the assembly. The wedge goes properly in place without fuss.

 

[F_R]

Well, learn something every day, they say.