Your tow-sports inboard—or any inboard—requires regular maintenance if it is to deliver long life and good performance. Seasoned boat owners know to make recurring assessments part of their routine. Here are several excellent midseason checkups you should make on your inboard-powered boat’s engine and driveline. In all cases, adhere to the engine-maker’s recommendations for maintenance. These are mandatory, not suggestions.
One tip to get started, if you haven’t done so already, is to write down the make and part numbers of belts, filters, fluids, and other service points so that you have these at the ready for future needs. Now, put these other tips into practice.
Transmission (Marine Gear)
Check the transmission—more accurately called the marine gear—fluid level with the boat on the level or in the water. First, run the engine for 5 minutes, shifting gears a few times. Next, pull the dipstick and check the fluid level. Also look for signs of discoloration, particles or a burnt smell. If you discover any of these, there is a problem; now is the time to call in a professional marine technician. By doing so, you might avoid dealing with a catastrophic problem. Check the filter too.
Belts
Feel for tension. A rule of thumb is that a belt shouldn’t deflect more than a half-inch when you depress it with your finger between the pulleys. Also, get out a straightedge to make sure the belts are running parallel to the pulleys they are on. Look for obvious signs of wear and slippage, and listen for squealing or singing sounds. All of these mean the belt needs either adjustment or replacement. Go out and buy a spare belt to keep aboard the boat, along with the tools to change it.
Filters (Air Filter/Spark Arrester)
To maintain a marine spark arrester (also known as a backfire flame arrester), inspect it for physical damage such as holes, tears or a poor fit. Replace it if you find any of these. Usually, you’ll simply remove any debris, clean it with a mild solvent or soap and water, and ensure that it’s completely dry before reinstalling. I like to blow-dry and clean it with compressed air. If it’s really dirty, or you haven’t cleaned it in more than a year, a commercial cleaner or brake cleaner can be used. If you go that route, wear a respirator, gloves, eye protection and other PPE.
Hoses
Check hoses on a cool engine. Hoses should be firm and not collapse easily, or even at all, when you squeeze them. If they collapse, replace them. Hoses should be securely clamped and able to withstand a solid tug on your part. Hose clamps should be tight, corrosion-free and mechanically sound. For engine intakes, and intakes for ballast, make sure that you know where the seacocks (shutoff valves) are located. Operate (aka exercise) the valve levers to make sure that they work.
Read Next: Midseason Sterndrive Maintenance
Prop
Visually inspect the propeller for dings and bent blades. Subtler damage can be seen by holding a straightedge vertically ahead of the prop and against the hull. Turn the prop by hand (key off, kill cord removed or spark plug wires removed), paying attention to the distance between the straightedge and each blade. All three, or four, blades should pass the straightedge at the same distance. If they do not, your prop is unbalanced. Send out a damaged prop for reconditioning. Even minor damage can damage your drivetrain, when you consider that a prop turns thousands of times per minute. This is the time to try that different prop you have been thinking of, and it is also a good reason to own a spare propeller.
