Transmission shift cables are typically found on stern-drive and inboard marine craft.
Shifter cables on marine craft provide the function of selecting the transmission gears that provide forward movement, neutral and reverse. The cable connects to a shifting lever at the cockpit location and runs along the rail or bilge gutter to connect at the linkage on the upper case of the motor. Shifting cables, although adjustable, can suffer some problems that impede or stop the shifting process. A boat owner should familiarize himself on the theory and operation of the shifter cable and know troubleshoot any problems that may arise.
Instructions
1. Install a muff flush device on your lower unit and connect it to a garden hose, if you have your boat on a trailer. If your boat is moored or docked in the water, leave it there for the cable shifting test. Make your first visual inspection of the cable condition. Look for any cracks or gouges in the outer sheath material. Any openings in the sheath will allow water inside to rust the cable and freeze it up. Replace any cable that has visible damage. Run your finger along its underside, from the shifter control box to the engine case, feeling for wrinkles.
2. Look for bends or 90-degree angles in the cable along its path. Any kinks will keep the cable from free movement and shifting properly. Check the transom cable mount for loose bracket bolts and the security of the fastening mechanism that connects the cable end to the shifting cams on the engine. If the cable is secured to the engine case by a cotter pin or nut, make sure they are installed correctly and tight. Tighten the flange nut that holds the sheath against the mounting bracket with an end wrench.
3. Use a screwdriver to remove the shifter box housing. Check the shifter box mounting bolts which hold the mechanism to the bulkhead and tighten them with a socket and wrench or screwdriver. Ensure that the cable connected to the shifter lever is secure and tight. There can be no excess play in the transom bracket or inside the shifter box which allows physical movement.
4. Start the engine and let it warm up in neutral. Cast off any lines. Shift the lever into forward gear and let the craft move forward. If the motor stalls after shifting into the forward gear repeatedly, inspect the small micro-switch on the transom bracket. The switch is called an interrupter switch, or kill switch. The switch can not be bent or disabled, because it assists in changing the pattern from forward and reverse to neutral. If the shift cable is stiff or binds for any reason, the switch will sense the tension and over-kill, stalling the engine.
5. Shift to neutral to see if the engine remains in gear. If the shift lever heavily resists, and you must use great force to position it in neutral, it indicates the cable has bound in the sheath, and the interrupter switch has failed completely. This results in a shifting lever that goes from forward or reverse gear, bypasses neutral completely and slams into the opposite gear. Consult your service manual for the proper switch replacement design and replace it. Any heavy tension required to move the shift lever into any gear, indicates a bound or dry cable -- replace the cable.
