Bellows are flexible rubber tubes that protect a boat's power train parts and provide a flexible exhaust pipe between the bell housing and the Gimbal housing. There are normally three sets of bellows in a boat: U-joint bellows, exhaust bellows and cable bellows. Normally, only the U-joint and exhaust bellows are replaced. The cable bellows hardly ever need replacement because there is no heat buildup. While cracked or torn bellows will not sink a boat, the resulting water seepage is usually disastrous for Gimbal bearings, U-joints or other power train parts. While most boat owners leave this job to the pros, the more adventurous tackle the job with the right instruction.
Things You'll Need
- Utility knife
- Bellows adhesive
- Replacement bellows
- Bellows clamps
- Bell housing pin tool
Unscrew the nuts that secure the power trim pistons to the out drive with a wrench. Remove the flat washers. Remove the power trim pistons from the studs on the out drive. Suspend the pistons out of the way by tying one end of a rope anywhere on the deck or swim platform of the boat, guiding the other end of the rope through the ends of the trim pistons and tying that end of the rope to anything on the deck or swim platform.
Remove the propeller. Unscrew the nuts from the out drive mounting studs. Remove the out drive by pulling it away from the bell housing.
Unscrew the screws that hold the trim stop on the right side of the bell housing and the trim sensor to the left side of the bell housing and remove them. Remove the pins or screws that attach the bell housing to the Gimbal housing.
Slice the U-joint bellows with a knife while pulling back the bell housing. After the U-joint bellows fall in half, slice the exhaust bellows with a knife. Note the position of the clamps that attach the bellows to the Gimbal housing and bell housing. Remove all clamps.
Clean all carbon, dirt and debris from the exhaust port. Apply bellows adhesive to the exhaust port and the inside of the exhaust bellows. Slip a clamp over the end of the exhaust bellows. Slide the exhaust bellows onto the exhaust port. Tighten the clamp in the previously installed position.
Slip a bellows clamp around the bell housing side of the U-joint bellows. Apply bellows adhesive to the inside of the bell housing side of the U-joint bellows. Slide the U-joint bellows onto the shoulder of the bell housing. Tighten the clamp in the previously installed position.
Slip a bellows clamp around the transom side of the U-joint bellows. Apply bellows adhesive to the inside of the transom side of the U-joint bellows. Slide the bellows and the bell housing over the shoulder on the Gimbal housing. While holding the bell housing with one hand, slip the other hand through the bell housing and adjust the bellows to ensure correct seating on the shoulder. Hold the bell housing in place until the adhesive sets. Tighten the clamp in the previously installed position.
Replace the pins that attach the bell housing to the Gimbal housing.
Apply bellows adhesive to the inside of the bell housing side of the exhaust bellows and slip a clamp over the bellows. Stretch the bellows back to the exhaust shoulder on the bell housing and slide onto the shoulder. Tighten the clamp in the previously installed position.
Reinstall the trim sensor and trim stop. Reinstall the out drive. Reinstall the propeller onto the out drive.
Untie and remove the rope suspending the power trim pistons. Reattach the power trim pistons to the out drive.
Tips & Warnings
- Refer to the individual manufacturer's shop manual for specific instructions on removing, installing and positioning parts.
- Do not rest the weight of the out drive on either the input or output shafts. Damage to the shafts is likely to occur.
- If replacing the cable bellows, refer to the power train manufacturer's and boat builder's shop manuals for specific instructions.
- Since neither the engine or out drive were turned, the input shaft splines should slide easily into the engine coupling. If the input shaft does not slip in, check the engine alignment.
- The out drive is a heavy item. Do not try to remove this alone. Enlist either the help of another person or the use of a mechanical device such as a tripod and winch to support the weight of the out drive.