Boat Engine Troubleshooting

By Tom Neale
Photos by Mel Neale
Published: April/May 2013

What's that funny smell? Do you hear a strange noise? Wait a second, that feels too hot! Stop and trust your senses. They've got some important news for you.

Using your senses of hearing, touch, smell, and sight can alert you to an impending situation with your boat that may be about to ruin your day. Here's how to heed the warning.

Your Sense Of Touch

Photo of hand touching engine parts
Very carefully touching some engine parts can help determine if there is excessive heating in places that should be cool.

Feeling Hot, Hot, Hot

Unusual vibration, whether in the boat or a component, is a sign of something amiss. It may be difficult to isolate, but you should try if it's safe to do so. Examples of potential problems: steering vibration may indicate something hung on the rudder or a system problem. Vibration in the hull over your shaft strut may indicate something caught on the prop or a bent prop. Vibration of the shaft may indicate the same or it could be a misalignment.

  • Feel for temperatures on all equipment regularly. A good time to do this may be during noise checks. Some parts you can touch with your hand, but if you don't know them, this could result in a serious burn. An infrared-temperature gun with laser is invaluable. With it, you can accurately determine normal operating temperatures for different components and write down the values. Check these areas:
    • Heat exchanger — The area where the engine water enters should normally be hotter than the other end where it exits.
    • Alternator — It will be hotter putting out higher amps or if the belt is too loose.
    • Exhaust — Abnormal temperatures at the point where raw cooling water enters your exhaust via the injection nipple can indicate a failing raw-water impeller, clogging heat exchanger, clogging injection nipple, debris in the raw-water strainer, engine laboring too hard, and other problems.
  • Rub some transmission fluid between your fingers shortly after running (be careful, it may be hot) or when you're changing it. If you feel grit, there may be a problem. There's usually some grit in many transmissions, particularly new ones as they're being broken in, but this shouldn't be excessive.
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