Outboard motors can power anything from dinghies and bass boats to large seafaring fishing boats. Their simple design, power, and the ability to detach from the boat are just a couple of reasons some owners prefer them over inboards.
When done right, a used outboard motor purchase can save you a lot of money. However, the challenging part is finding a good model and properly testing it.
As with any purchase of a hobby vehicle or expensive gear, contacting a professional or at least a knowledgeable friend to assist you in the inspection process can make a difference between buying a well-maintained motor or a lemon. To save you from getting stranded in the middle of nowhere, we have prepared a checklist to help you examine the motor in detail.
Make & Model
Yamaha, Honda, Mercury, Evinrude, and Suzuki are just a few among many renowned outboard motor manufacturers. There is nothing wrong with having a brand preference, but you should still do your research to find out if there are known problems or weak spots with a particular brand or model.
Measure the distance between the transom and the bottom of the hull. Also, consider the design, weight, and seating capacity when deciding on the amount of power you need. Then, compare it to the specification of the motor to see whether it fits on your boat.
Overall Appearance
A visual examination of the motor can tell you if it was submerged, poorly maintained, or damaged during transportation. The engine cowl protects the motor and the wiring from the elements. Scratching and cracks on the side appear when the motor is transported and stored on hard surfaces.
If you care about appearances, a replacement will cost you a few hundred dollars. However, cracks indicate neglect, so approach the purchase with care. The cowl gasket seals the engine housing. The new gasket will cost you a few dozen dollars. Towards the lower end of the motor, you should check for barnacles, rust, and oil seepage.
Running The Engine
Throughout the checklist, you should inspect components with the engine turned on, so we need to explain the nuances of starting and running it.
Outboard motors are made with reliability in mind, not efficiency. They can last a very long time, have relatively low compression and high tolerance to wear and quality of oil and gas.
When you start the engine on dry land, certain issues commonly arise. The lack of backpressure will cause the idle to be higher than usual, and the engine may stall a few times, especially if it is cold. You can almost ignore the initial problems, but after a minute or two, the engine should run smoothly, maintain idle, and rev up even on a stand.
Skegs are the gills located in the lower section of the shaft. The important part is to supply the Skeg with running water. Inside, an impeller pumps the water up and through the motor to cool it down. And though the engine itself can run for up to five minutes without water, the impeller can not, thus preventing you from adequately testing the cooling system.
Ask the current owner if they have tried to dry run the motor. If they have, it’s possible the engine wasn’t appropriately cooled.
Engine
Before starting the engine, look for signs of overheating, corrosion, and saltwater running. Discoloration and metallic stains of the engine block indicate overheating. Look for corrosion around the electrical parts and on the cylinder head. If the engine were running in saltwater, salt would accumulate between the cylinder head and block.
Once started, inspect the linkage and make sure everything is running smoothly. Shift through the gears, but do not over-rev before shifting. It is normal to see white smoke when running a 2-stroke engine, as it’s burning an oil-fuel mix. If the engine is a 4-stroke engine, the examination process is practically identical to a car.
Compression
If you could only check one thing on an outboard motor, it should be the compression. You will need a proper tool to remove the spark plugs and a compression gauge. Metal shavings on the spark plug indicate that the engine is wearing out from the inside.
The compression between cylinders should be minimal, with the total range between cylinders under 10 psi. Solid compression doesn’t equate to a good motor, but poor compression immediately rules it out as a good purchase.
Propeller
Set the engine into neutral and spin the propeller. That will tell you if the shaft is straight, which is of significant importance. Some wear and tear on the propeller is fine. But chips, dents, and asymmetry are problematic, as repairs or replacements can be costly.
Oil
Oil is located inside the lower unit, held back by a single screw. Unscrew it slowly and let some of the oil leak. Black oil is fine as long as it is clear and has a consistent viscosity. If it’s brown, milky, or chunky, there could be water inside the lower unit, indicating defective seals.
Cooling System
To check how well the engine is cooled, you will need to run it in water or use the Skeg mufflers. The system needs to pump the water out, or there is a blockage in the system. After running for five to ten minutes, touch the engine block. If it is still scorching hot, the engine is not getting the proper cooling.
Additional Equipment
When you are browsing for outboard motors, you should expect to get just the engine. However, some sellers might throw in the gas tank, battery, fuel lines, cables, and wiring harnesses, which can save you a lot of money post-purchase. Be sure to inquire with the seller about any of these additional features if interested.
