How to Take Off Lower Units on Boat Motors
- 1). Touch the gear case, the bulge that holds the propeller shaft, and slide your hand upward until you find the split between the exhaust housing; you'll see the fasteners that keep the lower unit attached. Usually, there are between two and three fasteners, either bolts or nuts threaded onto studs, visible on each side of the lower unit. The fasteners are usually threaded upward, rather than down and, depending on the motor, some fasteners may not be visible.
- 2). Lift the motor up, either manually or with the motor's tilt function, if the motor is so equipped. Find the motor lock or locking pin and lock the motor in the "up" position. Slide a jack stand under the exhaust housing and raise it into position to support the weight of the motor as an added precaution; it only takes a few seconds, and the time is well-worth the cost of the damage a 600-pound motor can do.
- 3). Reach under the forward, bottom edge of the engine block, or "powerhead," where you see the motor's shift control lever penetrate the motor's cowling. Find the spring latch or retaining nut that connects the shift lever to the shift rod, which continues down to the lower unit, and disconnect the rod from the lever.
- 4). Draw a line from the trim tab onto the plate directly above the propeller, called the "anti-cavitation plate," and use an open-end wrench to remove the trim tab; the line lets you line it up right when you put it back on. After you remove the trim tab, look for a hidden depression with a nut in it. Remove the nut with a socket wrench.
- 5). Inspect the fasteners and either remove the nuts from the studs with an open-end wrench or a socket, or remove the bolts from their bores. You may find that a thin-walled socket is the only way to remove some of the nuts. Retain both the nuts and the washers, organizing them by the location from which you removed them, so the nuts return to the same fastener and the same fastener returns to the same bore.
- 6). Pull the lower unit free from the motor gently, pulling the unit straight away from the motor to avoid bending the driveshaft or the shift rod. When you have pulled the lower unit completely free of the rest of the motor, move it to your workbench.
