• The Language Your Boat Speaks

    BOATING WITH ALL YOUR SENSES

    An outboard’s tell-tale, the stream of water that guarantees the water pump is working, is only one of many ways your boat talks to you. Your boat and engine are always broadcasting up-to-the-minute reports on their condition, and we don’t mean computer diagnostic systems. Some of the best information presents itself directly to your human senses, if you know how to see, hear and smell what they mean.

    What color is the exhaust? Exhaust is best heard but not seen. But when it shows itself, notice the color.

    • Bluish smoke means burning oil, either because a two stroke mixture is too rich, a four-stroke needs new rings, or somebody poured oil into the wrong hole. It can also indicate a dirty carb or stuck valve allowing fuel to mix with and dilute crankcase oil.
    • Black smoke indicates unburned fuel, which might mean adjusting the carburetor, cleaning or replacing spark plugs or replacing plug wires. It can also mean one or more cylinders is missing or not firing at all.
    • White exhaust is usually just condensing water vapor, common on cold mornings or high-humidity days. But if you suddenly start seeing it on a warm dry day, stop and inspect.


    What’s that sound? Small boaters operate in the open air, not as insulated from sound by the cozy cockpits we have in our autos. Always pay attention to the normal engine and propeller sounds. If you know what “normal” sounds like then you’re much more likely to notice the sounds that could be telling you something is wrong. To mention only a few sounds of trouble:

    • Rough running and sputtering can be an early sign of overheating and must not be ignored—overheating can destroy an engine in a minute. On older motors without overheating alarm buzzers, listening is even more important.
    • Metal-on-metal grinding, clicking or clunks may point to the lower unit: broken or worn gear teeth, a bad clutch dog or shift linkage, failing bearings or lack of lubricant.
    • Ringing or jingling sounds, or a low vibrating sound, can mean a loose or damaged propeller.


    Something smell fishy? Even when we aren’t aware of them, we are always noticing smells, and they can help you spot boat and engine problems.


    • Gasoline odor. Over filling a portable tank in the chilly morning can cause spills when fuel expands in the heat of the day. Also check for missing or loose fuel caps, leaking fuel lines or connectors, a cracked primer bulb, and portable tanks stored on an angle allowing fuel to spill from a vent or cap.


    • Do you smell burning rubber? Check for a belt rubbing itself against a misaligned or frozen pulley. Also check for burned, melted or overheated electrical wiring.


    • Sulphurous, rotten-egg smell? Lower unit lubricant has a characteristic odor even when new. Check for leaks and damaged seals, or a missing vent screw.
    • Oil smell. You’ll always notice some oil smell from two-stroke engines, but if the smell changes or gets more intense, investigate. Don’t smell any oil from a two-stroke? Be sure you didn’t forget premix your oil and gas when you filled up.


    It takes a little time to become familiar with the normal sights, sounds and smells of your boat and motor. Learn to take it all in and you’ll be more receptive to the reports of trouble or possible issues if something starts to go wrong.
    Comments 5 Comments
    1. Rockfishman's Avatar
      Rockfishman -
      Good Stuff!
    1. gl115's Avatar
      gl115 -
      thanks for E-mailing me this info.
    1. jeromewood's Avatar
      jeromewood -
      a little common sense goes a long way thanks
    1. jimvango's Avatar
      jimvango -
      Thanks for the good points. In watching my 2000 Mercury 10HP 4 stroke engine closely, I notice water trickling from an open port on the lower left shaft portion of the motor - just above the trim lift support. The flow increases with an increase in RPM. One mechanic says this is not a problem. I do have a strong stream from the normal engine cooling water port above. Any ideas?
    1. Loree Hill's Avatar
      Loree Hill -
      a little common sense helps go a long way thanks for the reminder