Making sure the best second hand outboard motors are purchased requires careful examination and attention to detail. The first area to inspect is the lower unit, including the propeller. Many second hand outboard motors will have broken skegs and damaged propeller blades. Any outboard motor that shows signs of overheating, such as burned and peeling paint in the cylinder head area, should be considered a high-risk purchase as well.
If possible, it is always wise to start and operate second hand outboard motors prior to purchasing them. By operating the motor in a barrel of water, it is possible to verify that the water pump is working. It is also possible to change gears and ascertain whether or not the transmission is in working order. Any overheating conditions can be seen in second hand outboard motors in a matter of minutes. Occasionally, spark plugs will foul and head gaskets will begin to leak as the motor begins to warm up. Cracked heads and cylinder blocks can also be detected on second hand outboard motors after a short operation in a water tank.
Any opportunity to operate a motor on a boat is a plus. By pushing the weight of a boat and passengers, a transmission problem can easily be identified. Slipping and popping out of gear while under power is a sure sign of a transmission problem as well. Some of these problems can be easily rectified, but others may require extensive and costly repair. This is why operating the motor in both forward and reverse gears is important.
Whether it be on a boat or in a barrel, it is wise to pull the plug from the lower unit after operating the motor and check for water. Many times second hand outboard motors will have cracks and bad seals in the lower unit. This will allow water to seep in as the motor is running and can potentially damage the gears. Checking the oil for signs of water contamination can be as easy as examining the oil for traces of foam, milky consistency or actual water escaping the lower unit before any oil begins to drain out.
Performing a compression test on second hand outboard motors is an easy task and can reveal signs of cylinder or piston ring wear. A cylinder leak down test can also show cylinder integrity. Bad cylinder head gaskets within second hand outboard motors will be detected by poor readings in either test.