Basic Tune Up Tips For Your Marine Engine

With spring right around the corner, boating season is about to begin! Of course, if you want to have a truly enjoyable year on your boat, you need to make sure it is in good working condition.  A big part of that task is making sure you conduct a thorough tune up of your engine before you hit the water.  In this article, you'll find some tips to help make sure you have covered all the steps of a proper tune up on your boat's engine.

• Unless your using the engine daily or several times a week, always use a fuel conditioner. Use it as recommended by the manufacturer and not more or less than directed. It will maintain the integrity of the fuel and protect your investment.  These chemicals can also protect your engine against the harmful effects of ethanol.
• Inspect and replace the sacrificial anodes as needed.  These components protect the metal alloys of your engine and your boat.  If they are corroded, then they are not able to do the job, and you risk damage to your boat.
• Check the propeller for damage and repair or replace as needed.  If the propeller is not in good condition, then it could significantly impact your boat's overall performance.

• Inspect and replace your spark plugs.  Depending on whether you mix the gas or the engine has oil injection, spark plugs on these engines typically require more frequent replacement.
• Inspect the spark plug wires and replace them if needed. Age and heat will affect the ability to carry spark from the coil to the spark plug. Please note that some plug wires are integral to the ignition coil (especially on newer engines) and cannot be replaced unless the coil is also replaced.
• Always replace your fuel filters! These are key to protecting the engine, whether it’s carbureted or fuel-injected. Repairs due to dirty fuel can be costly, and the best way to avoid them is with recommended fuel filter changes.
• If you use your boat in salt or brackish water, be sure to check your thermostat.  Thermostats can corrode quickly in these environments, so you will want to check them often to ensure they are still functional.
• Consider replacement of the water pump impeller as determined by the maintenance schedule or your history with the engine. The tell-tale sign is with the water discharge typically found on the lower engine cowl.  Examining the water discharge can help determine if water pump service is required. A weak discharge at higher rpm, or little or no discharge at idle speed is a good indication that the impeller is worn.
• Check the power trim function for operation. Check the fluid for proper level per the owner's manual.
• Grease all pivot points and lubricate linkages on the engine as recommended by the engine manufacturer.
• Many folks drain the gear lube and replace it during winterization.  If you did not conduct gear lube service at the end of the last season, you should definitely perform it before the next season begins.
• Check the tightness of critical fasteners, including steering components and engine mounting.  Your boat endures a lot of vibration on the water, and over time these connections can become loose.  Neglecting loose connections could lead to serious damage and risk of injury in the future.

• Hopefully, the engine oil and the oil filter were changed during fall storage, but if not, make sure to change it now. Changing oil in the fall maintains clean, fresh and contaminant-free oil on the engine bearings, along with all the critical friction points inside the engine.
• Spark plugs usually don't have to be replaced as frequently on 4-stroke engines as they are on 2-stroke engines. You should still inspect the plugs before you launch your boat, and replace them if they appear to be charred or fouled.  Otherwise, follow the manufacturer's recommended service interval.
• The age of your spark plug wires and heat will affect their ability to carry spark from the coil to the spark plug.  Just like with 2-stroke engines, some plug wires are integral to the ignition coil and cannot be replaced unless the coil is also replaced.
• Make sure to replace your fuel filters before starting your boating season.  These are key to protecting the engine, whether it’s carbureted or fuel-injected. Repairs due to dirty fuel can be costly and the best way to protect them is with recommended fuel filter changes.
• Just like with 2-stroke engines, inspect your thermostat regularly if you operate in salt or brackish water.  Adding this to your tune up checklist will ensure it isn't forgotten.
• A worn-out water pump impeller can cause major damage to your outboard engine.  Be sure to inspect the impeller and replace it if it is needed.  Just like we mentioned above with 2-stroke engines, you can observe the water discharge from the lower engine cowl to quickly identify if the impeller is working properly.
• Check the power trim function for operation. Check the fluid for proper level per the manual.
• Grease all pivot points and lubricate linkages as recommended by the engine manufacturer.
• Just like with 2-stroke engines, we recommend changing the gear lube during your winter storage service.  However, if you didn't take care of the gear lube at the end of last season, make sure you do so before you begin the next season.
• Check the tightness of critical fasteners, including steering components and engine mounting.  Your boat endures a lot of vibration on the water, and over time these connections can become loose.  Neglecting loose connections could lead to serious damage and risk of injury in the future.
• If there are any accessory drive belts in use, inspect and adjust them as needed. If they appear worn out, cracked or damaged, then they should be replaced before taking the boat out on the water.

• Hopefully, the engine oil and the oil filter were changed at storage. If not, be sure to change them before beginning the next boating season.  Changing oil in the fall maintains clean, fresh and contaminant-free oil on the engine bearings along with all the critical friction points inside the engine.
• Inspect the ignition system thoroughly.  Replace the spark plugs, distributor cap, rotor, points, condenser and spark plug wires as needed or recommended by the manufacturer.  In many cases, there are tune up kits available that include all of the components you need for a complete ignition tune-up.
• Check the accessory drive belts for wear or damage. If they are worn or cracked, then replace them.  Adjust all belts for proper tension.
• Replace the on-engine fuel filter and any remote or bulkhead mounted fuel filter.  This should be done before the beginning of every boating season, and in many cases, during the season as well.
• Inspect and replace the raw water pump impeller as needed or per the maintenance schedule.  If your impeller appears worn or if any of the rubber blades are broken or missing, you should definitely replace the impeller before starting the engine.
• On inboard engines, follow the recommended guide for transmission fluid and filter change. If you also have a V-drive installation, there may be separate fluid or oil to check and maintain.
• On stern drives, drain and replace the gear lube if this was not done at the time of winter storage.
• Stern drives have pivot points on the transom assembly.  These should be inspected and greased before each season.
• The rubber bellows for the universal assembly, shift cable and exhaust should be inspected and replaced as needed along with the hose that brings cooling water from the drive unit to the transom.  For popular stern drive models, there are transom service kits available that include all the necessary components for this maintenance.
• Grease the universal joints and input yoke drive spline on your stern drive. This will require removing the drive unit. While the drive is off, also check the engine coupler alignment to ensure it can make a good connection.
• If you have an inboard engine connected to a transmission, you should have the alignment of the propeller shaft to the transmission coupler checked and adjusted if needed.

Hopefully, the tips above give you some guidance for how to properly prepare your boat for a hassle-free boating season.  If you have any questions about proper preseason maintenance of your boat, just contact our ABYC-certified experts at (866)388-0390.