It doesn’t matter if you have an inboard or out board engine, the basics are the same. If you didn’t change the engine oil before parking the boat, now is the time to do it. Oil is the life blood of an engine and needs to be able to efficiently lubricate and cool the engine. Oil is also cheap when compared to an engine over haul. Reference your engine service manual for recommendations as to the recommended oil change intervals.
If your engine was winterized and treated for storage, you will need to clean or replace the spark plugs and change the fuel filters. It is easiest to just replace the old spark plugs with new ones. But if you are saving a few bucks, you can also clean and re-gap the old ones. All you need is a small stiff bristled wire brush and gapping tool.
Don’t forget to change the fuel filter before you head out on the water. Also make sure you have the tools and extra fuel filters on board before you go out for your first run. Many a boater has made it out on the water just far enough not to get back and had crud plug the filter stopping the engine.
Cooling systems should be checked and the fluid replaced or added to as necessary. All hoses, wires and belts should be inspected and replaced if dry or cracked. It is a good idea to carry an extra belt or two with you along with the appropriate tools to change the belt. Belt tension should be adjusted per the factory service manuals recommendations.
Transmission fluid, hydraulic fluids (power steering, power tilt) and oil injection tanks should all be inspected and refilled. While you are at it, check the bellows on the stern drive, packing or stuffing boxes hinge points, U joints etc. Fittings, cables and connections should be lubricated. Many of the components will have grease fitting so that they can be lubricated using a grease gun.
The lower unit, drive shafts and propellers should be inspected for nicks and damage. Basic aluminum propellers (especially on lower horsepower engines) can have minor nicks filed by hand. Paint can be touched up with a spray can of paint from a home supply or auto parts store.
But if you have brass, stainless, adjustable blades or any other type of high performance propeller, don’t take the chance of trying to fix it your self. Take the propeller to a good prop shop and have it repaired and balanced.
Make sure that when you remove the propeller that you lubricate the shaft to prevent corrosion and assist in removal in the future. It is always a good idea to have a back up prop on hand along with the appropriate nut or cotter keys.