Don’t risk costly repairs and headaches this season – Read the total motor maintenance guide now
“Take care of your motor and your motor will take care of you.”
These wise words, spoken by my father after I’d finally saved enough for my first fishing boat, still ring true.
Here’s the deal.
These days, Yamaha outboard motors have become remarkably reliable. A well-maintained motor will easily provide many hours of issue-free enjoyment. If we remember that the average boater adds only 100 hours a year to his motor, it’s easy to see how many motors can outlive their owners.
But there’s a catch.
While this makes boat owners proud, it makes it easy to forget about seasonal maintenance. Since it’s that time of year again, today we’re talking about nine essential annual maintenance tips to keep your Yamaha outboard motor running at its peak and guarantee it’s the longest life.
This way, your whole season will be nothing but a joyride.
#1 Inspect the Cowling
The cowling is the casing that protects the outboard powerhead from water intrusion. It also has baffled intakes that let air enter while releasing any unwanted water that finds its way in. To ensure everything inside is secure and working properly, it’s important to check the latches and the gasket at the beginning of every new boating season.
#2 Replace Spark Plugs
Every new year of boating means new spark plugs. For the “do it yourself -ers” spark plugs should be removed and inspected to check electrode to ensure there is no erosion of the electrode and that the spark plug is removable and not frozen in block. Regardless, spark plugs should be replaced every 100 hour or every year, whichever comes first.
Check for arcing by starting the motor in a dark space with the cowl removed. If you see blue flashes, that means the current is escaping and grounding to the motor.
#3 Service the Anodes
Anodes, also known as zincs, are made of sacrificial metal, meaning they prevent corrosion and deterioration to other metals on your Yamaha outboard motor. Because outboard engines operate at high temperatures, galvanic corrosion can spread quickly from both the internal and external anodes.
Why does this matter?
If unattended, this corrosion will attack the engine and eat it away. This means it’s absolutely crucial to clean or replace all anodes each year.
Boaters who operate in salty, brackish water are particularly prone to external anode corrosion. To service the external anodes, remove them first. Apply sandpaper or a wire brush to the metal, clearing away any accumulated gunk. If 30% or more of the anode has been eaten away, replace it.
That’s not all.
Internal anodes protect the engine block, heads, and exhaust from corrosion, yet often get overlooked. To service the internal anodes, remove the outboard cowl. Depending upon your model, look for between 2-6 interior anodes. Clean them with a wire brush or sandpaper, replacing any that are badly corroded.
Pro Tip: Never paint over internal or external anodes. This renders them useless and allows corrosion to attack the outboard motor freely.
#4 Change Engine Oil and Filter
Every 100 hours or annually, whichever comes first, you should change the oil in your Yamaha outboard motor. In preparation for the end of the season, many boaters will change the oil and then let it sit for the winter. You don’t want to do this, as it can lead to condensed moisture gathering over time.
Instead, change at the beginning of the season to flush whatever’s collected during the winter. Changing engine oil and oil filter with Yamaha engine oil as well as a Yamaha filter is the way to ensure the longevity of your motor.
#5 Service the Water Pump
The water pump is the heart of your Yamaha outboard motor’s cooling system. The flexible rubber impeller, located inside the shaft housing at the top of the lower unit, is what requires maintenance.
Driven by the motor’s output shaft, it acts as a propeller to push water throughout the cooling system. The impeller vanes that circulate the cold water must make a watertight seal against the inside of the pump to work.
But impeller vanes become stiff and dry with age, especially if the motor is used infrequently. Even if your motor sees a lot of hours, the impeller vanes may be worn or damaged. When the vanes become ineffective, the cooling system pressure drops and this leads to overheating.
If you do not see water coming from the overboard water indicator, it’s a sure sign that the pressure is low and something in the cooling system is malfunctioning. If neglected, you may not notice until the pump fails and the motor overheats, which could cause significant damage. Replace the impeller to avoid any hassles and protect the motor.
Look at the pump housing too, as it may have been scored by sand and debris.
#6 Fuel System
Fuel is a major maintenance point for boaters for several reasons.
First, your gasoline degrades as it sits. Octane levels can drop by 2 points in a matter of months, especially in humid climates. This is problematic when running on low octane gasoline or gasoline containing ethanol.
Yamaha outboard engines are engineered to run off a minimum of 87 octane, but today REC 90 is what is preferred. Lower octane fuel creates issues with pre-ignition and detonation in the cylinders, meaning you lose power — but also that pistons rattle and finally break.
One way to overcome this issue is by not allowing your gasoline to become old or stale. If so, it needs to be removed from your fuel tank and disposed of properly and fresh REC 90 gasoline added. As far as fuel additives go, we recommend Yamaha fuel conditioner/Ring Free.
Ethanol fuel should be avoided at all costs since it attracts water and corrodes aluminum gas tanks.
I can’t emphasize this enough.
Be sure to refuel your motor before your next trip, not after. Why? Water builds up in the fuel tank as it sits, as every boat has an open fuel vent system. Whether or not you’ve just filled up, moisture will still accumulate.
If you fill up the day of the trip, you’ll get fresh fuel with higher octane to mix with the old. Keeping your motor running on high octane gas keeps the engine running better, for longer.
#7 Lower Unit
The lower unit of your Yamaha outboard engine is like the transmission for your car: the lower unit lube needs to be changed every 100 hours or annually, whichever comes first. The engine moves power through the vertical drive shaft to the lower unit, where you find the water pump, anti-ventilation plate, and propeller.
This is where the forward and reverse gears work as well. You can avoid lots of issues and by consistently replacing the lower unit oil. Even more frequently than recommended. It is cheap insurance.
There’s less than a cup of gear oil in the lower unit. Ask your local Yamaha specialist or consult your owner’s manual to check the recommended interval. Check the level of oil at the upper plug, but also check the lower plug as well, noting its color after a long season of sitting.
If the oil looks milky, there’s water leaking into the lower unit from a faulty seal. Do not use the engine if your lower unit oil is milky, the lower unit could be severely damaged.
Your propeller is what delivers power to the water. For maximum performance, make sure your propeller is tip-top before heading back into the water.
Start by checking the blades for damage such as cracks and dents. A blade that’s bent from impacting a soft bottom is harder to spot, and the odd vibration it creates will be the only giveaway that you’re out of balance and not pitched right.
If you feel this, visit your local Yamaha dealer to have the propeller rebalanced.
While the prop is removed for inspection, check for any fishing line that may have wrapped around the prop shaft seal. When line melts, it can destroy the seal and allow water into the gear case.
Older propellers will often have issues with the rubber hub cushion. Like any rubbery material, this gets dry and hard with age. The acidity and heat coming from the exhaust are a double-whammy.
When the hub material dries out, the bond between hub splines and barrel prop will fail, meaning the prop shaft is disconnected from the prop. Replace the rubber hub cushion or the propeller itself when you see cracks and the rubber feel hard.
The hydraulic steering system directs the thrust, delivering superb control even at low speeds. Before taking your boat out of storage this season, check the valves in the system to eliminate any feedback, making the task of steering easier and more precise.
Look at the steering system fluid level and bleed the lines if your steering has become sloppy. When air gets into the system, the quality of control on the water diminishes. Check for hydraulic fluid leaks around the helm, hose connectors, actuators and if you find any, bring your engine in for service to your local Yamaha dealer before hitting the water again.
The Last Word
Before you boat, this year, don’t overlook the maintenance of your Yamaha outboard engine. Boating season maintenance slip past many boat owners, but these oversights can lead to costly repairs and headaches both on and off the water.
Avoid the hassles by paying your trusty engine a bit of attention before breaking it out of storage. Investing just a bit of time and energy on maintenance is the surefire way to guarantee years of high-performance boating.
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