Substitute for OMC Shift O-ring #301877, Sierra 18-7100

[Sputter]

The Mercury shift-rod o-ring #25-85594, passed the pressure test with flying colors.

My homemade test device leaked where I screwed it into the gearcase oil overflow, probably because I didn’t want to waste a proper plug washer/gasket.

I repeatedly tested with soapy water applied to all seals and screws at 7-10 psi.  I also vacuum tested.

Lastly, I submerged the unit in water. The gage needle didn’t budge, and no air bubbles emerged even when I repeatedly moved the shift rod up and down.

I’m calling it a win.

1956 Johnson 15 Hp, FD-10
1958 Johnson 5.5 Hp, CD-15

1 user thanked author for this post.

David Bartlett

[Author]

Posts