Outboard marine motors can suffer a number of maladies that cause hard-starting or no-start conditions, but they usually turn over via the pull start or electric starter. One of the more serious problems involves a freeze-up or locked position when the motor refuses to turn at all. Locked-up motors result from long periods of storage, worn components or insufficient lubrication. Getting the engine to turn over requires some patience, a few products and special tactics.
Unsnap the quick-release fuel line hose from the outboard motor, which is near the carburettor. Disconnect the electrical wire jack that attaches to the power pack. Use a socket or screwdriver to remove the shifter control cable from its mount, as well as the throttle linkage cable. Unscrew the motor mount clamps and remove the motor from the transom of the boat. Use an assistant to help with the lifting.
Place the motor in an upright position on a dolly truck, so that the propeller faces outward, and screw the motor mount clamps around the top plate of the dolly truck. Tie bungee cords around the lower unit case. Transport the motor inside a garage area. Determine the orientation of the cylinders, whether they have a horizontal or vertical configuration on the motor. If horizontal, lay the truck dolly down on its frame, with the spark plug holes facing up. Leave the dolly upright if the pistons are already vertical.
Unsnap the top motor cowl case and pull the plug wires off the spark plugs. Use a socket and wrench to remove the spark plug (or plugs). Attach two feet of clear plastic hose on the tip of a clean turkey baster and insert the free end of the hose down into the spark plug hole. Fill the turkey baster with penetrating oil, and then inject 1/59.1 to 29.6ml of oil into each cylinder. Wait about six hours and repeat the oil injection into the cylinders, but use only 14.2gr per cylinder.
Inject penetrating oil into the spark plug holes for the next three or four days, once in the morning and once in the evening. Use 14.2gr each time, in each cylinder. Afterward, let the penetrating oil soak for a full week. Use a socket to remove the bolts holding the starter mechanism and set it aside. Notice the crankshaft nut on the shaft. Fit a six-point socket over the crankshaft nut and attach an electric or pneumatic impact wrench to the socket. Place rags over the spark plug holes.
Set the impact wrench for medium pressure, if it has a variable adjustment, and set the direction of rotation for a clockwise spin. Turn the impact wrench on for four or five seconds, letting the vibration hammer of the tool shock the shaft. Watch for any movement of the starter ring. If the engine begins to turn, stop. Remove the rags and inject more penetrating oil into the spark plug holes and let it soak for two hours.
Cover the spark plug holes with rags. Attach the impact wrench to the crankshaft nut and turn it on. Look for movement. If it moves, turn up the pressure on the impact wrench and let it spin freely. If the motor refuses to turn, add more penetrating oil and periodically use the impact wrench to turn the crankshaft nut. It should eventually free up. Remove the rags and let the excess penetrating oil escape from the cylinder, while you spin the motor.
Use a socket and wrench to replace the spark plugs. Reattach the spark plug wires and close the top motor case cowl. Have your assistant help you remount your engine on the transom then connect the cables, fuel line and wire jack you removed.
Seized engines can also result from spun rod or crankshaft bearings. In this case you will need to add several ounces of penetrating oil to the engine oil and perform the same procedures. A breaker bar can be substituted for an impact wrench, but it is important to use a hammer to tap the breaker bar to shock the stuck components.