Are you looking forward to that trip on the boat this weekend? When was the last time you serviced the vessel?
Can you remember when you changed the spark plugs and filters last? Boat maintenance is one of the most overlooked components of boat ownership.
The last thing you need is to find yourself dealing with mechanical engine failure out on the ocean. However, sooner or later, a malfunction happens to every boat owner.
We decided to prepare you for the worst with this list of common boat engine problems.
- Dirty or Blocked Fuel Filter
- Twisted Fuel Lines
- Dead Battery or Loose Terminal Connections
- Snapped Drive Belt
- Motor Overheating
- Ignition Switch Failure
- Dirty Spark Plugs
- Electrical Issues
- Flooding the Engine
- Dirty Carburetor
- Damage to the Propellers
- Transmission Problems
- Burst Exhaust Hose
- Hydraulic Issues
- Steering Issues
- Major Mechanical Failures
- Fuel and Water Leaks
- In Closing – Learn to Maintain Your Boat Motor Yourself
Dirty or Blocked Fuel Filter
The most common source of engine failure on the water involved problems with the fuel line. When there is no fuel going to the motor, it starves and stalls.
If you have a full tank of gas and the boat is inching its way through the water while you have the throttle open, chances are you have a problem with a blockage in the fuel filter.
It’s an easy problem to fix, just replace it with a new fuel filter; they’re cheap and easy enough to fit without the need for professional assistance.
If you’re on the water without a spare, clean out the filter and knock any buildup loose. That should be sufficient to get you on your way.
It’s also important to note that fuel can separate and go bad if you leave it in the tank for too long between trips. Avoid this problem by draining the tanks after each trip if you don’t use the boat often.
Twisted Fuel Lines
The fuel lines also present a point of failure in your boat engine. Check that the line running from the motor to the tank is free of obstruction, and kinks are a good place to start.
Crimped or twisted fuel lines won’t supply any fuel to the engine, starving it into submission or preventing it from starting. If there are any twists or crimps, get a marine mechanic to replace the fuel line.
Dead Battery or Loose Terminal Connections
Most modern boats come with electric starters. So, if you turn the key to start the boat and hear a clicking sound, that means the battery is dead.
Most boats come with two batteries. One will be isolated from the rest of the circuit, powering the electrical points on board, and the other will be for the motor.
Sometimes you may set the switch wrong, draining both batteries with the bilge pumps and lights. If you feel like your motor is taking longer to start or is slower in turning over lately, it might be time to service the battery or replace it.
If you’re offshore when this happens, you’ll have to hail another vessel for a jump, or if you’re onshore, plug it into the battery charger and try to turn it over. If the engine cranks with the same power but won’t start, it’s time for a new battery.
Snapped Drive Belt
Another common engine problem is a loose or snapped drive belt. Typically, you’ll notice the voltage meter or overheating light flash on the dashboard, saying it can’t charge the alternator anymore.
You’ll need to replace the drive belt, so make sure you keep a spare one on board, or you’re not going home any time soon.
Make sure you have all the tools you need to change the belt and practice changing it ahead of time, so you know what to do when it happens.
The temperature gauge on the dash will start moving closer to the red when your motor starts to overheat. It might signify that the cooling loop isn’t getting sufficient water flow.
Sometimes, you’ll find an obstruction in the raw water intake that you’ll have to remove to solve the issue. Servicing the impeller often will go a long way to preventing overheating.
Ignition Switch Failure
If the ignition won’t start, it’s likely the battery that’s the problem. However, it also might be an issue with the ignition circuit. Check that the ignition switch isn’t loose.
If everything is okay, it could be the battery or an electrical problem. Prevent electrical connection issues with regular inspection of your wiring harness.
Dirty Spark Plugs
Another common reason for engine failure is dirty spark plugs. If you notice that the engine performance is lagging and it’s been a while since your last service, the chances are the spark plugs need replacing.
A healthy spark plug looks grey and dry. If it’s oil or white color, it’s a sign that there is too much oil in the engine or it’s running too hot. If the spark plug feels wet, it could be because there is water in the fuel.
If you find the boat stalls while accelerating, you could be dealing with a simple problem like someone accidentally knocking the kill switch for the motor. Maybe it’s something as silly as forgetting to fill the gas tank before leaving the harbor.
However, the stalling could also occur due to problems with the electrical system on the boat. There may be a chance it’s a tripped breaker or a blown fuse. Wear and tear of the witting may also lead to a loose connection causing the problem.
Flooding the Engine
If you can’t seem to get the engine to turn over and you’ve tried turning the ignition a few times, you might flood the engine. Flooding usually occurs from repeated attempts to start the boat with the choke out.
The solution to the problem is to wait and let gravity drain the fuel out of the system. Or you could try opening the throttle to the halfway position to burn off the fuel if the ignition catches.
Carburetor models are the most prone to flooding, and it doesn’t happen in injection fuel systems. If your engine floods, you also can remove the cowling and give the top of the carb a blast of compressed air or starting fluid.
Aim the air or starter fluid directly into the manifold as you start the engine. If the engine begins briefly and dies, the problem is with the fuel system, not the motor.
If you have a carburetor model engine, you need to service it to keep it clean. The carb picks up residue from the fuel, forming blockages over time. While the fuel filter does a great job of catching debris in the fuel. With time, it becomes less efficient, and some debris makes it through to the carburetor.
If you notice the performance of the motor lagging, it could be because the carb is dirty or you have dirty spark plugs.
Either way, you’ll need to book the boat for motor service. Ethanol fuels make this problem worse, and you’ll need to ensure you have regular maintenance on the crab to keep the motor running at optimal efficiency.
Sometimes, it’s possible to service the carb yourself if you have a smaller motor. Check the owner’s manual for details on removing the cowling, identifying the crab, and cleaning the jets. If you have a mechanic friend, they should be able to show you how to clean the crab in a few minutes.
Damage to the Propellers
If you open the throttle and you find the steering and motor start to shake, you’re dealing with damage to the propellers.
If there is prop damage, you’ll also notice that the shaking noise gets worse the faster you go, and the engine sounds like it’s running hard, even when slowing down at the slip.
If the boat isn’t getting up to planning speed when you open the throttle or use more gas than usual, there might be an issue inhibiting the normal movement of the propeller. There might be debris around the prop, or you might have a broken shear pin.
Replace the shear pin or pull off the debris, and the problem should go away. Sometimes, the noise might occur due to tiny scrapes or dings in the props. Damaged props need replacement or refurbishment with a professional repair shop.
If you open up the throttle when idling and the motor doesn’t respond, you have an issue with the transmission. It’s probably likely that the shifter won’t engage the right gear to get you moving forward.
If you have low transmission fluid in the gearbox, you’re going to encounter problems with shifting. Keep extra transmission fluid on board and regularly service the boat.
Burst Exhaust Hose
If you find that your boat is suddenly filling with water, keep a calm head and don’t panic. The exhaust hose likely burst, and it’s bringing water on board.
Shut down the engine, and the water stops rising. Ensure you service the boat often and that the service company thoroughly inspects all the engine components to prevent this situation from occurring out at sea.
It’s annoying when you arrive at the launch after a long day on the water to find the tiller for the engine doesn’t work. The problem is with your boat’s hydraulic system.
In most cases, you’ll have to locate the trim release valve and lift the tiller manually into position. Ensure you have a toolbox with adjustable wrenches on hand so you can releaser the manual valve.
All steering systems have the potential to fail, even tiller systems. You might encounter issues with the failure of hydraulic steering rams or the ends of steering cables failing and giving way.
A close visual inspection for corrosion or leaks in the hydraulic system detects problems before they get out of hand. You can center “rudders” or “outdrives,” and you can bring the boat most of the way home using a “jury rudder.”
Major Mechanical Failures
Boat owners rarely encounter a complete mechanical failure out on the water. Occasionally, older models may experience issues like broken camshafts, cracked cylinder heads, or dropped valves. If a total mechanical failure happens at sea, you’ll have no choice but to radio for help.
The Coast Guard will arrange a tow to your nearest shipyard for repairs. Total mechanical failures are the most expensive to fix as they usually involve stripping the motor and replacing costly parts. In some cases, it might be worth looking into the cost of a replacement motor.
Sometimes upgrading will only cost you a few hundred dollars more than repairing an old motor.
Fuel and Water Leaks
A water or fuel leak is alarming, but the good news is that it’s a rare occurrence. Common causes of these leaks include corrosion in the exhaust water jackets. Or it may occur from people standing on the fuel lines during maintenance work.
Hoses may perish or clips loosen due to the effects of engine vibration. Regular visual checks of your motor, especially after long periods of inactivity, are essential for detecting problems early on.
Carry spare clips and hoses with you and ensure you double-clip any new hoses for added security. Top of the coolant levels in closed cooling systems because it contains vital corrosion inhibitors.
In Closing – Learn to Maintain Your Boat Motor Yourself
You can learn to do plenty of tasks by yourself instead of farming them out to the local marine mechanic. Working on minor servicing and repairs yourself will save you hundreds or thousands of dollars that pay for gas money and parts throughout the year.
We recommend reading through articles and watching YouTube videos on basic maintenance for your boat. YouTube can teach you a lot about general boat engine maintenance for beginners. There are also in-person classes you can attend at locations along the coastlines of the United States. Look online for live classes in your area.
You’ll learn how to bleed fuel lines, change spark plus, clean the carburetor, and much more. Keep a selection of spares onboard your boat, along with your toolbox. If anything goes wrong out on the water, you have everything you need to make a quick repair and get back on course.