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

[LARRY CATON]

Here are some pics of the Mercury Marine o-ring with my casing and shift rod.

The pic with the package shows my original, dried up o-ring beside the new orange one. The orange ones I think are new old stock.

The orange is a coating that flakes off with handling. I’m guessing it’s not supposed to do that, but the o-ring is plump and soft.

When I dry fit the o-ring with the shift rod, it was snug to the point where the o-ring would pucker in and out when I slid the rod. It seemed workable as is, but I decided to squirt some motor oil in the well to see if it improved the function or leaked.

I’m happy to report that the oil made the shift rod slide effortlessly, and the o-ring was like a squeegee, only allowing a light oil film pass by. The oil remained pooled on top of the o-ring.

I’m calling it a successful substitute for the OEM Johnson o-ring.  If the o-ring fails the pressure test, I’ll post a retraction! Lol

 

1956 Johnson 15 Hp, FD-10
1957 Johnson 5.5 Hp, CD-14
1958 Johnson 5.5 Hp, CD-15