Engine Problems?

March 2011 News

Nothing is worse than getting out on the water, pulling away from the shore and the engine sputters and dies about 100 yards away from the dock. After attempting to restart your engine with no luck, you grab your skis, fishing nets and your wife and you both slowly paddle back to the dock. There are a few tricks to checking your pontoon or deck boat's engine before you take off for the day. These little tasks could save you from costly engine repair, groans and mumblings from your family and sore arms from paddling.

1. Overheating

It's not uncommon for a boat's engine to overheat. Be sure you check the water intake area before taking off for the day. If you are out on the water and the engine overheats, check and see if there is something stuck in the water intake. If there is something jammed inside, remove it and then wait for the engine to cool down. After it has cooled, try to restart the engine.

Another problem that can cause your engine to overheat is that the water pump impeller has blown. Make sure that you check this before taking off from the dock as well. If you are out on the water when the impeller blows, you can use the drain plug located in the engine's water jacket to get your engine in running condition again.

Pour fresh water into it and limp slowly back to shore. Watch your temperature gauge to make sure it doesn't get too hot again and stop to cool it down if it does. This won't fix your problem, but it will help you get back to shore, and checking your water pump impeller before heading out on the water will help save money on an engine reconstruction. 

2. Oil Gasket

If your oil gasket is leaking at all, don't go out on the water. Your engine shouldn't start if your oil gasket is leaking, but if you do find yourself out on the water with a leaky oil gasket, cut one out from your marine chart. Add layers to get the right thickness and slowly head back to shore. Replacement oil gaskets aren't too expensive, but if you let it all leak out, replacing your dry engine will get pricey.  

3. Lube

Grease every fitting, swivel and U-joint that you can find at least once a season. Rust can easily build up on your steering cylinder and can seize your steering ram. When you try to turn the wheel with your own muscles, you can break the gearing in the helm and trash the cable. 

4. Spark Plug Wire

Spark plug wires that have cracked can short out, especially if the day is rainy or it is rather humid. When this occurs, your boat engine is likely to misfire. Be sure you keep electrical tape in your toolkit to close up the wires and keep wetness out. Be sure you cover every crack you find so it doesn't short out. This will work until you can replace the spark plug wires.

5. Correct Wiring

In order to protect the boat and engine, the pontoon needs to be electrically connected to the pontoon's engine via a ground wire. If not, galvanic corrosion can set in.

6. Exhaust Manifold Failure

This is the most common in older petrol marine engines. The tell-tale signs of exhaust manifold failure are the emulsified creamy deposit in the oil filler cap and often the creamy oil in the sump.
Marine exhaust manifolds are water cooled and most manifolds are cast iron. This material is porous and spends its life soaking up the salt from the water that passes through it until ultimately, corrosion eventually breaks down the internal walls that separate the exhaust gas from the cooling water. The resulting hole then sprays salt water up into the exhaust ports, causing all the associated problems.

7. Incorrect alignment and poor or worn out engine mounts

Your drive system vibration can damage transmissions and engine mounts and the boat hull itself. To avoid a total engine replacement, replace or upgrade the struts, strut bearing and engine mounts as soon as your engine shows signs of these being worn out.

Sometimes flexible rubber engine mounts are installed on engines to reduce the amount of vibration transmitted to the hull. Where an engine has flexible mounts and rigid gearbox and shaft couplings, the mounts move but the shaft doesn't. A gyrating engine results in a misaligned propeller shaft. This causes shaft vibration and wear of the gearbox bearing. On drive trains equipped with a drip-less shaft seal, the increased movement can cause the seal to leak. The only remedy is to modify the shaft by installing a flexible coupling.

8. Contaminated Fuel

If your pontoon or deck boat has a very rough idle at startup and perhaps even stalling of the engine at idle speed, your fuel might be contaminated. Never buy gas at a service station when the tanker truck is filling up their tanks or shortly thereafter! They count on water present in the storage tanks to remain on the bottom below the outlet going to customer pumps.

Since gas is lighter than water this works quite well. But after dumping five or 10 thousand gallons of new gas in, it does a bit of mixing. In a short while the gas and water separate again and all is okay. If the boat is not already equipped with a fuel-water separator between tank and engine, you might want to consider installing one.

9. Gummed-up Carburetor

Your pontoon or deck boat motor might run fine in the driveway with muffs but when you put it in the water, it stalls at low speed. One of a couple of things could be happening. The motor is stalling in the water because when you put it in gear it is now under a load.

The most common problem is a gummed-up carburetor. This comes from sitting with old gas. Even with fuel stabilizers it can happen. The best way to prevent it is to drain the carburetors when you winterize the motor. But do not run the motor until it is out of gas. By doing that, you are leaning the motor out and leaning the oil mixture out that is used for rust protection.

Depending on your motor, there is a small drain screw either on the front or side of the bottom and this holds the float bowl of the carburetor. Take the float bowl out and drain.

Taking these precautions will keep your motor from stalling at low speeds in the water.


There are so many things that can go wrong with a boat when it is out on the lake. Boats are like cars and trucks in that they need to have maintenance done on them as often as possible, especially if you take your boat out a lot. Being prepared is essential to fixing your engine quickly. Carry spare parts with you that may be necessary to repairing your engine. Be sure you have tools in your boat to help you out as well. Most importantly, be sure you have the necessary information that will help you to fix your boat.

  • Like what you read?

    Want to know when we have important news, updates or interviews?

  • Join our newsletter today!

    Sign Up
You Might Also Be Interested In...

Send to your friends!