Mercury Marine's MerCruiser stern drive system consists of the engine, outdrive and operator controls. After years of use, the shift cable tends to stretch causing the need for adjustment and realignment. When the shift cable is in the forward position, the cable will be pulled inside the sheathing at the shift plate. When it is placed in reverse, the cable will become fully extended.
Remove the engine cover and locate the shift control plate assembly on the left rear portion of the engine. Examine the condition of the cable and connections. Clean any corrosion from the surfaces with a stiff brush. Wipe the area clean with a shop towel.
Find the shift lever stud on the left side of the shift plate and see if it is located at the bottom of the slide opening. Loosen the nut using an open end wrench and push the stud down with your fingers as you re-tighten it if it is not in the lowest position.
Have your assistant carefully grasp the propeller with his hands and rotate it counterclockwise as you gently shift the operator controls into the forward wide open throttle position. The propeller shaft will stop when the forward clutch has been engaged.
Pull gently on the plastic cover over the shift cable near the shift lever stud to remove any slack left in the cable. Remove the clevis pin and brass barrel from the shift plate and rotate the barrel until the excess cable has been removed. The clevis pin hole will be aligned with the end of the shift cable when the proper adjustment has been made.
Rotate the brass barrel away from the plastic cable guide four complete turns after the alignment has been made and place the barrel and end of the cable end back on their positions on the shift plate. Reinstall the clevis pin and retaining nuts.
Have your assistant grasp the propeller again with his hands and rotate it clockwise as you shift the controls into the reverse wide open throttle position. The propeller shaft will stop when the reverse clutch has been engaged.
Loosen the shift lever stud with an open end wrench if the clutch did not engage in Step 6. This is the same stud you adjusted in Step 2. Push the stud slightly upward and re-tighten it. Repeat Step 6 and continue the process until you have full reverse clutch engagement.
Check and secure all cable connections and close the engine cover.
- Wear gloves to protect your hands when working with boat propellers.
- The MerCruiser stern drive is equipped with an engine cutout switch on the shift plate. This switch deactivates the engine while shifting to avoid damage to the drive gears. Investigate for cable damage or misalignment if the switch mechanism is not directly centered in shift plate groove. Newer models use a plunger and older versions use a roller mechanism.
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