How to Install an OMC Transom Bellow Seal

by Andrea Walk

OMC Cobra is the name of a manufacturing company that makes marine engine parts, such as transom bellow seals. A bellow is a rubber seal used on outdrive marine engines to protect the U-joint and the exhaust bellows located near the transom on the outdrive, as saltwater intrusion can be harmful to these parts. OMC transom bellow kits include both bellows and mounting clamps and Gimbal bearing. Installing the bellows will take one to two hours.

1.

Use a socket set to remove the propeller nut and then pull the propeller nut, along with the propeller, off the bottom of the outdrive.

2.

Remove the nuts holding the trim pistons in place on the outdrive with the socket set and then hang them out of the way with a bungee cord.

3.

Remove the outdrive lower unit mounting nuts and then pull the outdrive lower unit away to access the bell housing.

4.

Loosen and remove the screws holding the bell housing to the Gimball housing with a Phillips screwdriver.

5.

Use a Phillips screwdriver to remove the clamps holding the old exhaust port and U-joint bellows in place. If necessary, cut the old bellows away with a sharp knife.

6.

Wipe away dirt and debris from the exhaust port. Wipe a small amount of bellow sealant from the kit onto both the exhaust port and the inside of the bellow and then slip the new clamp and bellow in place. Tighten the clamp with the Phillips screwdriver. Slide the new clamp over the U-joint and then wipe bellow sealant on the inside of the joint bellow and then slip it on. Tighten the clamp with the screwdriver.

7.

Attach the bell housing to the Gimball housing and insert the screws and tighten them.

8.

Lift the outdrive lower unit and replace the mounting bolts.

9.

Slip the trim pistons back into position on the inner section of the outdrive and then tighten them with the socket set. Slip the propeller back into place and tighten the propeller nut with the socket set.

Items you will need

  • Socket set
  • Bungee cord
  • Phillips screwdriver

References

  • OMC Transom Bellow Service Kit Owner's Manual; OMC Cobra

About the Author

Andrea Walk began writing in 2001, authoring user guides for technical software. She holds a Bachelor of Arts in political science from Loyola University, where she was a member of the Dean's Grade Review Committee for English. Walk is a member of the Automotive X-Prize team Global-E.