Outboard Maintenance Jobs You May Have Overlooked

When you think about outboard maintenance, you think about stuff like engine oil changes, gearcase lube changes, spark plug replacements, the usual.

Here at Boats.net, we’ve covered basic maintenance like engine and lower unit oil changes, winterization, and fuel system maintenance and repairs plenty of times. So much so that we’ve been compiling video playlists on these topics just so you can find them all on the same page. And that’s ok. 

These subjects are of high priority, and can be spun in a variety of ways. For example, Mercury outboard oil changes for different models. The basics are the same but the steps and supplies may vary between models. In this article, we’ll focus on tasks that may not immediately come to mind when we think about outboard maintenance. 

Overlooked Outboard Maintenance Jobs

Prop Parts Maintenance

We’ve covered boat propellers more times than we can count. However, we haven’t talked enough about maintaining the parts that hold an outboard propeller in place. 

Start with making sure the prop shaft is adequately greased. Keeping the prop shaft and splines lubed in marine grease protects them from wear and corrosion. You should grease the prop shaft at least twice a year, once at the start of the boating season and again at the end of it. 

While you’re doing propeller maintenance, make sure all of the prop parts and hardware are tight to keep the prop itself from flying off. Inspect the prop shaft for tangled fishing line or any other debris, and give it a good cleaning. Don’t forget to inspect and replace the prop shaft seals while you’re at it.

Outboard Fuel System Lines

As mentioned, we’ve covered outboard fuel system maintenance (changing fuel filters, adding fuel stabilizer, etc.) quite a bit, but what about inspecting fuel lines? 

Rotted fuel lines are a major fire hazard. Start with the fill hoses that are connected to the fuel tank. Fuel hoses usually need to be changed out every five years, but they should be inspected regularly for leaks, cracks and rotting, and replaced as needed. Also, take the time to inspect the clamps that secure the fuel lines in place. Check those for corrosion, and make sure they’re lubricated and tightly secured. 

Cooling System Flush

Yes, that’s a picture of a thermostat below. We’ll get to that in a second, but first, outboard maintenance 101 tells you to flush the engine after each use.

You probably already thought of that, but another type of flush that gets surprisingly overlooked is a cooling system flush. This maintenance task helps keep your outboard’s cooling system free of corrosion and from overheating. Check the manufacturer’s recommendation for how often to do cooling system flushes. 

As for thermostats, which are essential to keeping the outboard from overheating, inspect them once in a while and change them out as needed. Another easy cooling system check you can do to prevent overheating is inspecting the water intake, output and passages for clogs and cleaning them out.

Outboard Electrical System Maintenance

One often overlooked maintenance task is actually going through the electrical system to inspect wires and their connections, which also wear out over time.

This simple task can start with an inspection of the battery’s electrical connections. Clean any dirty battery terminals with a brush, and use a corrosion inhibitor to protect them. Check the wires that connect to the battery, and then dig a little deeper for a full wiring inspection. 

If you find any corroded wires or connections, grab a crimper, some heat shrink tubing and a heat gun and make those connections watertight. Don’t forget to check the fuses while you’re at it, and replace any that are blown out. 

Anode Replacement

An incredibly simple but often overlooked outboard maintenance task is to change out external anodes, which are the first line of defense of corrosion protection in the water.

These sacrificial metals, commonly made of zinc, can be found on the trim tab, behind the propeller nut and around other parts of the motor. Their job is to absorb galvanic corrosion from the water before it can reach other engine parts, hence why they’re commonly referred to as “sacrificial anodes.” They’re meant to get slowly eaten away, but if you don’t change them out regularly, eventually they become useless and then the outboard’s other metal parts will be next.