To help make sure your spring tune-up and cleaning is thorough and effective, we've compiled the following pre-season checklist.
Change the Oil. A ski boat's oil should be changed every 50 hours of running time or at least once a year, even if it hasn't been run at all. After shutdown, air (which is full of moisture and other contaminants that wear on internal engine components) will find its way into the oil supply. If your motor is not equipped with an oil-removal system that pumps the old oil to an outflow hose, it means affixing an adapter to the dip-stick well, siphoning with an oil-drain pump into an appropriate container, then disposing of the sludge at an approved oil-recovery site. It is also essential that the oil filter be replaced with each oil change. The filters are spin-on types, usually located in a reasonably accessible location on the plant.
Filter the Fuel. Most fuel problems can be traced to a clog somewhere in the fuel-delivery system. Many times the filter element itself will have begun to deteriorate without obvious indications, adding to those contaminants already running through the fuel system. Some manufacturers have filters that house the fuel pump as well. You can only get these through an authorized dealer, but the added expense will mean clean fuel and protection of more vital (and expensive to repair) fuel-delivery components.
Clean the Cooling System. As with your car, your boat has a two-stage cooling system: a closed system that circulates coolant inside the engine, and an external system that cools the coolant. Your boat's motor has a near-identical first-stage cooling system, but instead of a radiator, the second stage dissipates heat using cool water drawn in from beneath the boat. The system can suck up all manner of dirt, weeds, grass, etc. To prevent a clog or buildup, the external system is equipped with a filter (more like a screen and commonly called a “sea strainer”). When removing and rinsing out the strainer, be sure not to lose the 0-ring seal found at the bottom of the threads on the strainer housing (cup). If the ring is lost or not seated correctly when you reinstall, you will not get a good seal. Air will be sucked into the system, retarding its effectiveness, and the seal will leak – but only after you shut down the motor and walk away. This check should be performed frequently throughout the season. The cooling system is powered by a water pump containing impeller fins, which resemble the blades on a fan. When any of the fins go bad, they begin to damage the others. Therefore, once a pump starts going, its condition will accelerate, and replacement as soon as possible is required.
Remove Corrosion. In modern motors with fuel injection, electrical power is even more important than on older models, since the juice provides not only the spark but also powers a number of other systems integral to the fuel delivery and sparking sequence.
Half of any electronic equation, and a most common source of power deprivation, will be improper grounding connections. The average engine has five to six ground connections, all of which should be checked regularly, removed, cleaned and reconnected. Several products are now on the market which require only a squirt or two on a connection to keep it corrosion-free.
Service the Battery. If you have an older-style (maintenance-type) battery, it is important to make sure the cells are kept filled with electrolyte fluid. You should always wear protective eye wear when servicing your battery and never attempt to service a battery that is warm to the touch. Pull the individual cell caps off and look to see that the metal plates are completely submerged. Refill using only pure, distilled water. If the levels are more than a few centimeters down, the fluid will need to be checked with a hydrometer to test the specific gravity for adequate acid content. Also, peek to see that the plates inside the battery are not corroded and pitted. If you have a no-maintenance battery that is not holding a proper charge, you'll need to take it to a battery shop and have it tested for voltage, amperage and load.
Don't Ignore the Starter. Starters are mounted low on the engine and thus subject to splashing water and grease in the bilge. The starter terminals can corrode quickly, so regular periodic checks are in order. While you're down there, take a moment to manually toggle the automatic bilge-pump float switch to be sure it moves freely and kicks the pump on when at an appropriate level.
Pull the Plugs. Typically, spark plugs need to be changed every 200-300 hours. If you change the plugs, be gentle. An exhaust manifold leak could let water puddle at the base of the plugs, causing them to rust externally. When subjected to the twisting strain of a socket wrench, they may break off, leaving no option but to tear the engine down to the cylinders. Always unscrew spark plugs with just a little pressure at a time.
Check the Belts and Hoses. Belts and hoses are the easiest to maintain. Check the belts for tightness: More than a very slight deflection when you push or pull means the loop needs to be tightened or perhaps replaced with a new belt. Look on the belt's edges and running surface for excessive wear or steel strands showing through. Typically, the alternator belt will wear the most. Slippage due to a worn belt also generates heat. A telltale sign is when you notice paint chipping off the alternator pulley. Paint hates heat. Another sign to look for is a deposit of black soot somewhere near a pulley. This is actually belt dust and indicates accelerated wear. Look up under the engine cover. Often, the greatest deposit of alternator-belt soot will be out of sight, unless you're looking for it.
Hoses should appear sound, without cracks and supple to the touch. Most leaks occur on the ends, next to the hose clamps. Look for blisters and creases that may indicate a hose about to blow.
Inspect the Mounts. Two last things before you close the engine box. The motor mounts are subject to the greatest degrees of corrosion, contamination and vibration. Though much beefier than the rest of the hardware, they can wear and loosen. Don't tinker with the motor mounts – leave the job to a trained service technician. The fittings must be tightened from the bottom up and, if adjusted incorrectly, will misalign the engine, inflicting undue and potentially damaging strain on the transmission, shaft and shaft packing gland.
Spray it Down. Once everything is checked out, spray a mist of thin lubricating oil, like WD-40, all over the engine. This way, everything stays lubricated, paint lasts longer, dust and grime can be wiped off easily (so the engine runs cooler), and any fluid leaks will be noticed immediately. Don't worry if you over-spray onto a belt or pulley. If you get a little belt slippage upon startup, the lube will dissipate quickly.
Haul the Hull. Even if your boat runs great year in and out, it is a good idea to haul it at least every other year to check things like steering cables, rudders, shafts, stuffing-gland material and the prop. There is no time line for servicing these components, but that doesn't mean they should be forgotten. Improper wear in these areas will usually be very noticeable. In the case of the shaft packing, a continually operating automatic bilge pump tells the tale.
Listen for Clues. Internal components like valves, heads and timing chains may last forever or may eventually require repair. Though physical inspection is not possible without disassembly, there will usually be some very pronounced symptoms that should not be ignored before a qualified mechanic is brought in to troubleshoot. Do not ignore new noises, rattles, vibrations or sudden changes in the instrument readings. Like those who ignore the warning signs our bodies put out as physical problems develo
p, he who waits may already be too late. – L.J. Wallace