Basic Outboard Maintenance

Technological advances are changing the world we live in, and marine outboards have benefitted from that new tech over the last two decades. Today’s outboard engines start easier, run smoother, and deliver great power while maximizing fuel economy and minimizing emissions.

Such traits often lead to boaters snoozing right through anything related to preventive maintenance. That type of attitude is a fast track to expensive problems and very possibly the shortening of an outboard engine’s life, whether it’s one of the old two-strokes or the newest of the four-strokes.

To deliver years of trouble-free service and keep boat operating costs to the bare minimum, every outboard should get a thorough cowl-to-prop service once a year for a boat used in freshwater – and up to quarterly if used in brackish or saltwater. The investment in time and money is minimal because most of the maintenance work can be done right in your own garage using basic hand tools, and the routine you go through is pretty much the same regardless of the type of outboard.

Break Out The Drain Pan

Basic outboard maintenance begins with lubrication. Clean, high-quality engine oil is the lifeblood of any high-performance engine, be it in a vehicle or on the transom of a boat. Outboards, however, are under far more stress than the typical automotive engine because they are often under constant load – sometimes at near max RPM for long periods of time. So oil and filter changes at regular intervals, in accordance with the owner’s manual, are critical. The first, and most critical, oil and filter change is usually between 20 and 50 hours. This is the break-in period when the oil basically flushes the engine of any normal wear particulates that may have been left during the building process. Marine dealers often say changing the oil and filter every 100 hours, or at least once a year, whichever comes first, is usually sufficient.

Changing the oil is relatively simple. Read the owner’s manual and follow the steps. One trick to keep the oil in the filter from spilling out over the lower cowling is to tilt the engine up as far as it will go and turn it to the side the filter is on before unscrewing the filter.

Once you’ve gotten the oil taken care of and have it filled back up, drop the engine to its level position and check the oil level on the dipstick just like you do your tow vehicle. (Of course, two strokes typically have the oil mixed with the gas.)

The Greasy Side

Outboards can’t survive without a good grease job. A small grease gun kit, which typically costs $25 to $50 depending on brand and style, is a great investment. Just make sure the grease is formulated specifically for use in water. Only use a grease designated as “waterproof” or “water-resistant.” Lucas Oil makes excellent products for this, as does Star brite.

Pump the new grease into the zerk fittings found on the steering tube (if cable type) and the pilot shaft until you see a little of the old grease ooze out. Use a towel to wipe up the excess grease. Grease the tilt tube and any other places where you find zerk fittings.

There are a lot of pivot points on an outboard. Check and lube each one as best you can. This is especially true of the shift and throttle linkages. Put a little water-resistant grease at each linkage point. Lubricating these places extends the life of the moving parts and makes shifting and throttle control smoother.

While the grease gun is out, pull off the propeller and clear the splines of any fishing line that might be wrapped around the shaft at the seal. Monofilament can cut into the seal, which, in turn, will allow water into the gear case. Then grease the splines before reinstalling the prop.

Gearcase Lube

While you’re at the lower unit, change the gear lube. This can be a messy job, but it’s critical in the first dozen or so hours of the new outboard break-in process. That’s because “high spots” on the gears get worn down during that time, leaving little bits of metal floating around in the oil.

Manufacturers put a magnet in the drain plug that catches this type of metallic debris. When you remove the drain plug, clean off the magnet before reinserting.

The challenge with changing the gearcase oil is that you must fill from the bottom of the gear case until you see it come out the upper vent. It’s not a difficult task. Most gearcase oil containers have a spout that inserts into the lower port that makes it easy to squeeze the tube until the new oil comes out the top.

Changing the oil and gearcase lube yourself can be a real money-saver because the shop rate these days can easily top $150/hour depending on where the dealer is located. But keep in mind doing this yourself means you’ll need to find a place to properly dispose of the oil and gear lube without creating an environmental hazard.

Water Pump

The rubber vanes inside the pump will take a set and lose their effectiveness after a couple years. Outboard experts say if the engine is more than two years old and subjected to running in muddy water or tidal areas, that type of water accelerates impeller wear. This job can be challenging and typically involves dropping part of the lower unit. Check your manual. If you don’t do it yourself, plan to have a service technician do this at least every two years – though doing it every year is cheap insurance. A decreasing amount of water coming out could be an indication of a problem.

Focus On The Fuel System

With the messy part over, turn your attention to the fuel system. When you give your outboard the annual once-over, check the fuel hose and primer bulb, if it has one. UV exposure will attack anything dark in the boat, and that shortens the life of any rubber component.

Also consider the fuel itself. Even though today’s four-stroke fuel systems are state-of-the-art, it’s a good idea to add some fuel stabilizer and conditioner to the fuel tank, consistent with the manufacturer’s recommendations. Many prefer using appropriate additives (such as Sea Foam SF-16 or Sta-Bil 360) with every tank of gas – mixed according to the directions on the bottle.

Fuel conditioners, among other things, help to prevent moisture buildup, a problem many see during the summer in regions where the humidity is high. This can also be a problem during winter storage, but that is beyond the scope of this article.

Another benefit of a fuel stabilizer/conditioner is that it helps gasoline retain its octane rating even after it sits in the tank for two or three months. When the octane starts going south, it begins to form a varnish that gums up the fuel filter and, of more concern, the tiny jets and injector orifices in the EFI system – or in the carburetor, if your outboard has one.

Some fuel suppliers, such as ValvTect, say it includes additives. Do your research.

Be Fuel-Wise

During the once-a-year engine inspection it’s good practice to replace the fuel filter on the engine. Some dealers back-flush them to get rid of the dirt and other crud that find their way into the fuel tank. But for the DIYer, it’s much more convenient to replace the filter.

Some four-strokes also have a water/fuel separator filter on the engine. It looks like a little oil filter-type cartridge with a paper element inside the canister. This filter’s job is to catch water. So if you see water in it, the system is doing its job protecting the fuel system. It may also mean that it may be time to replace the element.

This is not the place to skimp. The best advice is to replace the water/fuel separator filter at least annually. Also, some outboards have a larger external filter in the fuel line between the tank and the engine. These should also be inspected, drained, and serviced. Take a permanent felt marker when you put the new filter in and write the date somewhere so a year from now you know it’s time to change it again.

Obsess Over Anodes

The last item on the general outboard maintenance list is super important – and often overlooked by DIY outboard (and sterndrive) boat owners: checking and replacing the anodes on both the outside and inside of the motor. Marine dealers make this a regular part of a 100-hour service. However, anodes should be inspected at regular intervals long before that time.

Anodes, often called “sacrificial anodes,” are parts made of softer metals like zinc (saltwater), aluminum (salt/brackish water), or magnesium (freshwater). They are attached to various parts of an outboard motor’s case, lower unit, and engine.

The primary function of anodes is to prevent galvanic corrosion of critical engine parts that occurs when different metals are submerged in water and create an electrical connection, which causes one metal to corrode. These metal parts include the prop, engine block, and lower unit and their components. The anodes protect those critical items by “sacrificing” themselves to that corrosion.

“The anodes on and inside today’s outboards are a critical part of outboard maintenance,” says Chris Bond, owner of Crown Leisure Marine in D’Iberville, Mississippi. “We tell our customers those anodes need to be inspected every three months when the boat is used in brackish or saltwater, and at least twice a year for those used in freshwater. “

The ones owners typically forget about are the ones in the block that help control corrosion in the cooling system,” says the master outboard technician. “When those anodes deteriorate, they allow water intrusion into the engine, which will cause big problems.”

Replacing anodes is done with basic hand tools, but you must know where they are located. Those in the engine block may require pulling the manifold, replacing gaskets, and torquing bolts to spec. In these situations, this may be one of those maintenance items best left to a certified marine technician.

Spit & Polish

Once the mechanical aspects have been addressed, consider giving the outboard a little TLC in the looks department. Marine manufacturers recommend applying a synthetic wax or polish like Premium Boat Shine or Meguire’s Flagship Premium Marine Wax to painted surfaces. If you spend a lot of time on the water, give that outboard a good wax job every couple of months.

Another suggestion from the marine techs is to coat the powerhead with a light mist of protectant/lubricant such as LPS HardCoat Corrosion Protectant or Boeshield T-9, which is a special protectant/lubricant developed by Boeing for use on aircraft. Before you put the cowl back on, take a couple seconds to spray or wipe a film of silicone all along the rubber seal. A product such as Yamalube Protectant keeps the cowl seal pliable.

Outboard care advice may vary when you’re storing your outboard for the winter, but that’s another article altogether! A little preventive maintenance goes a long way when it comes to keeping your time on the water trouble-free and those outboard operating costs minimized.