... You can have a ton of problems and find yourself stranded in the water. ... It can also be dangerous if the motor decides to fail when you are a long way from shore or trying to outrun rapidly changing weather. ... If it is currently mounted on a boat, take it for a test ride. ... Make sure it idles smooth and comes up to full speed without hesitation. ... Watch for any type of fluid leak. ... Ask the owner about the age of the motor and if there is a record of maintenance and repairs. ... Remove the cover (outboard motor) and look for signs of leaks and cracks. ... Check the prop for any signs of damage and wobble. ... You’ll need a compression test to check the cylinders. ... Any more than that indicates excessive cylinder and ring wear or possible valve leaks on four stroke engines. ... A good mechanic could prevent you from making a very costly mistake. ... Buying a used boat motor is a lot like buying a used car. ... The opposite is also true. ... Believe me, this is no fun at all ...