How to maintain 9.9 HP, 15 HP & 20 HP Suzuki outboard motors

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Suzuki Maintenance Schedule

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What will be Covered in the Guide?

  • Inspection and Replacement of Spark Plug
  • Breather and Fuel Line Inspection
  • Engine Oil Change
  • Gear Oil Change
  • Lubrication
  • Anodes/Bounding Wire
  • Oil Filter
  • Fuel Filter

Inspect and Replace Spark Plug

Your Suzuki Outboard motor comes standard with a specific spark plug for normal usage - NGK MR6K-9. A spark plug operating typically presents a very light brown color. If the standard plug doesn't seem suitable for your operation, it's recommended to consult your authorized Suzuki outboard motor dealer.

Notably, non-resistor types of spark plugs can interfere with the electronic ignition's function, leading to misfiring or causing issues with other electronic boat equipment and accessories. Therefore, using only resistor-type spark plugs in your outboard motor is crucial.

Using improper spark plugs or improperly tightening them can cause severe engine damage. Experimenting with other spark plug brands can risk engine damage, which may not be covered under warranty. When installing a spark plug, seat it as far as possible by hand, then use a wrench to tighten it to the recommended torque setting or the specified rotation angle. The tightening torque should be 10 – 12 N·m, and the rotation angle for a new plug should be 1/2 – 3/4 of a turn.

Avoid overtightening or cross-threading a spark plug as it can damage the aluminum threads of the cylinder head.

To ensure a strong spark, clean and adjust the plugs at the intervals shown in the maintenance chart. Remove carbon deposits from the spark plugs using a small wire brush or spark plug cleaner, and adjust the gap as per the guidelines.

Note that if the spark plug condition shows excessive wear, breakage, melting, erosion, yellow deposits, or oxidation, it should be replaced with a new one. Ignoring these signs could lead to difficulty in starting the engine, increased fuel consumption, and potential engine troubles.

Inspect Breather and Fuel Line

Another important step in maintaining your Suzuki Outboard engine involves inspecting the breather and fuel line. Both these components play critical roles in your engine's operation, and their proper functioning is essential for safety and performance.

Start by checking for leaks, cracks, swelling, or other visible damage on the breather and fuel lines. These signs indicate a serious problem that needs immediate attention and repair. If any damage is detected, replace the affected lines as soon as possible due to its functions. It is crucial to remember not to use the engine until the proper maintenance has been conducted. Operating the engine with a damaged breather or fuel lines can cause severe issues, including fuel leakage.

Fuel leakage is a serious hazard that can lead to explosions or fire, severely damaging persons and property. Therefore, if you're unsure about the condition of the breather or fuel lines, it's recommended to consult with an authorized Suzuki dealer since they have the necessary expertise to accurately assess the situation and advise on the appropriate course of action.

Change Engine Oil

Maintaining the proper engine oil level and quality is crucial for the performance and longevity of your Suzuki Outboard engine. Changing the engine oil should be done when the engine is warm, allowing the oil to drain thoroughly from the engine. Below is a step-by-step guide on how to change your engine oil:

  1. Start by positioning the motor vertically and removing the motor cover.

  2. Proceed to remove the oil filler cap.

    Warning: It is crucial never to perform any engine oil procedure with the motor running, as this could lead to serious injury. Always ensure the motor is shut off before performing any engine oil procedures.

    Notice: Prolonged trolling can reduce oil life, potentially leading to engine damage. If your engine is used for extended trolling, change your engine oil more frequently.

  3. Place a drain pan under the engine oil drain plug to catch the draining oil.

  4. Remove the engine oil drain screw and the gasket, then let the engine oil drain out.

  5. Once the oil has completely drained, secure the engine oil drain plug with a new gasket.

  6. Refill the engine with SAE 10W-40 or 10W-30 engine oil up to the upper level. The oil capacity is 1.0 L.

    Caution: The engine oil temperature could be high enough to burn your fingers when the drain plug is loosened. Wait until the drain plug is cool enough to touch with bare hands before removing it.

    Notice: A previously-used gasket may leak, leading to potential engine damage. Always use new gaskets; do not re-use old ones.

  7. After refilling, check the engine oil level.

    Note: To avoid incorrect measurement of the engine oil level, check the oil level only when the engine has cooled down.

  8. Finally, reinstall the oil filler cap and properly dispose of the used oil. Do not dispose in the trash, ground, drain, or into water

Change Gear Oil

Monitoring and maintaining the correct gear oil level is critical for the smooth operation of your Suzuki Outboard engine. To check the gear oil level, remove the upper oil level plug and look into the hole. The oil level should align with the bottom edge of the hole. If the oil level appears low, add the specified gear oil until the level matches the bottom edge of the hole. Afterward, reinstall and tighten the plug.

If you need to change the gear oil, follow these steps:

  1. Make sure the motor is in an upright position and place a drain pan under the lower casing.

  2. Remove the gear oil drain plug, then remove the gear oil level plug.

  3. After the oil has drained completely, inject the 80W-90 gear oil into the lower drain hole until it just starts to come out of the upper hole. You will require approximately 0.25 L (0.26/0.22 US/lmp. qt.) of oil.

  4. Reinstall and tighten the gear oil level plug, then quickly reinstall and tighten the gear oil drain plug.

  5. Dispose of used gear oil properly. Do not discard it in the trash, or pour it on the ground, down a drain, or into the water

Note: To avoid insufficient injection of gear oil, check the gear oil level 10 minutes after completing step 4. If the oil level is low, slowly inject more gear oil until it reaches the correct level.

Lubricate Your Engine

Proper lubrication is critical for the safety, smooth operation, and longevity of each working part of your Suzuki Outboard engine. Regular lubrication minimizes friction, prevents rust, and extends the life of moving parts. The following chart indicates the lubrication points on your motor and the recommended lubricant for each:

  • Throttle linkage: Use marine-grade water-resistant grease.
  • Throttle cable: Use marine-grade water-resistant grease.
  • Clamp screw: Use marine-grade water-resistant grease.
  • Propeller shaft: Use marine-grade water-resistant grease.
  • Swivel bracket: Use marine-grade water-resistant grease (applied with a grease gun).
  • Steering bracket: Use marine-grade water-resistant grease.

Note: Before applying grease through the steering bracket grease nipple, lock the motor in the fully tilted-up position. This will ensure proper grease distribution and prevent potential damage to the steering bracket.

By adhering to these lubrication guidelines, you can ensure that your outboard motor continues to operate efficiently and reliably. Remember, using marine-grade water-resistant grease is crucial due to the water exposure your outboard motor encounters, helping to protect against corrosion and wear.

Preventing Corrosion and Anodes

Anodes are a vital part of your Suzuki Outboard engine's defense against exterior corrosion. These components control electrolysis and prevent corrosion by sacrificially corroding themselves to protect the other parts of the engine. This means that anodes will deteriorate instead of the components they're designed to safeguard.

Given the essential role of anodes, it's important to periodically inspect each of them. If you notice that about 2/3 of the metal has corroded away, it's time to replace the anode.

Note: Internal anodes attached to the cylinder block/cylinder head should be inspected and replaced by your authorized Suzuki Marine Dealer.

Notice: Improper anode maintenance can lead to galvanic corrosion damage on underwater aluminum surfaces, such as the lower unit of your engine. To ensure your anodes are effectively protecting your engine, keep in mind the following:

  • Regularly check the anodes to ensure they haven't become detached.
  • Avoid painting the anodes, as this would render them ineffective.
  • Clean the anodes periodically with a wire brush to remove any coating that might decrease their protective ability.

In addition to anodes, bonding wires play a crucial role in protecting your engine from electrolysis. Bonding wires electrically connect engine components, creating a common ground circuit that allows them to be protected by the anodes.

These wires and their terminals should be checked periodically to ensure they haven't been damaged. Regular inspection of bonding wires helps maintain the integrity of your engine's common ground circuit, promoting overall engine health and longevity.

Change Oil Filter

Maintaining a clean engine oil filter is crucial for the efficient operation of your Suzuki Outboard engine. This component filters out contaminants from the engine oil, protecting your engine's internal parts.

The engine oil filter should be replaced periodically by an authorized Suzuki Marine Dealer. The first replacement should occur at the initial 20 hours of operation, typically within the first month. After this initial replacement, change the engine oil filter every 200 hours of operation or every 12 months, whichever comes first.

When installing the new filter, avoid overtightening it. Instead, hand-tighten the filter to prevent potential damage. Additionally, apply a thin layer of oil to the filter's seal before installation. This step ensures a proper seal, preventing leaks, and maintaining the correct oil pressure within the engine.

For the best performance and longevity of your Suzuki Outboard engine, use Suzuki Oil Filter 16510-45H10. This filter is specifically designed for your engine, assuring its proper function and maintaining its performance over time. Adherence to these guidelines and regular oil filter changes will help ensure your engine reliability and performance. 

Change Fuel Filter

The fuel filter in your Suzuki Outboard engine plays a vital role in maintaining the engine's performance by filtering out any impurities in the fuel before it reaches the engine. Over time, the filter may become clogged with these impurities, which can affect the engine's performance.

To ensure the continued efficient operation of your engine, the fuel filter should be inspected periodically by an authorized Suzuki Marine Dealer. Regular inspections will help identify if the filter is clogged and needs to be replaced.

When replacement is necessary, ensure to use the correct part for your Suzuki Outboard engine. The recommended part number for the fuel filter is 15410-87L00. Using the correct part ensures the best performance and longevity of your engine. Regular inspections and timely replacements of your fuel filter will help keep your engine running smoothly and efficiently.