Many stern-drives have flexible gaskets, called “bellows,” that seal the water out where the universal joint, shift cable and exhaust run between boat and drive. Their flexibility allows the drive to trim and turn while under way, but they can dry out and crack due to heat, harsh weather or age. In fact, since you can’t apply antifouling to flexible rubber like a bellows, marine growth, especially barnacles, can create a tear. Specific replacement procedures vary by model, but knowing the basic steps can empower you to change the bellows yourself, or at least to be a better negotiator when the time comes to do the deed.
Step 1. Get the service manual for your drive and identify which fasteners, clips and gaskets to remove and in what order. The factory manual is best bought from your dealer, but Clymer (clymer.com) and Seloc (selocmarine.com) publish aftermarket manuals for about $35.
Step 2. Remove the prop, then the drive. It’s easier if you have a friend to help, but if working solo, support the drive as it slides out using a hoist or a 1/2-inch diameter line tied to the rafters or a stout tree limb. Hit the shaft on the ground and you could bend it. A hoist ring with a half-inch diameter and 13 threads, available at hardware stores, can be screwed into the lube-oil level tube on some drives; others have a lifting ring welded on beneath the cowl. You can order the proprietary part as specified in your service manual.
Step 3. If the drive is right-hand, put the shift lever in reverse; if it’s left-hand, put it in forward; if it’s a dual-prop drive, refer to your service manual. Now disconnect the shift cable at the engine. That done, remove the toggle at the cable end, leaving the straight-threaded rod so you can pull it through the transom.
Step 4. Disconnect the trim limit switch on the portside of the upper housing by removing the screws that secure it. Allow it to dangle on its cable, taping it off on the transom.
Step 5. Remove the hinge pins, if equipped, using a hinge-pin tool chucked in a socket wrench. These are often very hard to remove. Lubricant spray may be required. Don’t just lean on the wrench — “work” the fastener; don’t break it off.