When you get tired of shelling out close to $100 to have the oil changed in your four-stroke outboard engine or cleaning up after someone else’s job, you might consider getting out your owner’s manual and changing the oil yourself.
Unlike your automobile, your outboard’s drain plug is usually located below the power head. On my Yamaha, it’s in the rear, but placement varies. These drains are either angled downward or at a right angle to the leg, which means the oil will flow outward into a catch basin as well as down along the leg onto the anti-cavitation plate and entire lower unit.
Before you start, purchase a new drain plug gasket, oil filter, and enough oil to refill the crankcase and filter.
You’ll also need a can large enough to contain all the oil, a plastic funnel fitted with a piece of garden hose that reaches from just below the drain to the mouth of the can as it sits on the ground, and a standard metal oil-changing pan.
Wear grubby clothes, and have lots of rags or a roll of paper towels handy.
Changing the oil
- Lower the engine to the operating position, and place the oil-changing pan underneath the lower unit.
- Hold the funnel underneath the drain, and unscrew the plug. Apply slight pressure to hold the plug against the opening, and slowly pull the plug away and catch as much oil as possible. Let the dregs drain down the leg and into the oil-changing pan. Inspect the magnetic metal plug and remove any metal particles with a paper towel.
- Remove the old gasket, and replace it with the new one.
- Clean the outside of your engine around the drain and replace the plug to the specified torque. If you don’t have a torque spec, finger-tighten the plug until the gasket makes contact with the drain hole’s surface, and then tighten no more than one-half turn with a wrench.
- Remove the engine cowling, locate the oil filter and place several paper towels under it. Remove the filter with an oil filter wrench, and place the filter in the pan under the lower unit.
- Prepare the new oil filter by using your finger to wet the filter’s rubber gasket with a little bit of oil. Carefully screw on the filter. If it sticks or balks, make sure it isn’t cross-threaded. Don’t screw the filter on too tightly, and never use a wrench.
- Pour the oil from the drain pan into the can, and remove the old oil and containers.
- Clean off the engine using rags or paper towels. You can also wash the surface with bilge cleaner. Rinse and dry it.
- Pour in all but one-half quart of the suggested amount of new oil into the oil fill port. Close the port, start the engine, and run it for a minute while providing cooling water to the engine before shutting it off.
- Give the oil a few minutes to run back down into the sump, and then check the oil level on the dipstick. Add extra oil if necessary, and check the plug and filter for leaks.
Now, you’re good for another 100 hours or six months, whichever comes first.
D/1st/Lt David H. Osmolski, AP, of Charlotte Power Squadron, has been repairing boats since high school when his first boat, a canvas-covered canoe with cedar ribs, leaked in gallons per minute and required constant repair. Dave’s current boat, a 16-foot Carolina Skiff, gives him plenty of opportunities for repair and upgrades, so look for more of his maintenance articles in upcoming issues.
Article courtesy David Osmolski and the USPS Ensign