08.02.2011 05:45 PM

Important Summertime question

Up at the lake with assorted sons, daughter, mother, cousins and dogs. Out tubing, with abandon over big waves, and oil indicator – and, more seriously, engine temperature indicator – start flashing. When Merc 150-equipped Larson  is going straightish – or pulling kids water skiing – no red flashing lights.

I think I’m getting false warning lights, due to all the tube-related zigs and zags.

Am I right? Am I wrong, and the boat should be towed to the deep part of the lake, and sunk? Over to you, team wk.com!


  1. Iris Mclean says:

    Sounds like it might be a wiring fault it they only flash when you’re cranking the wheel.

  2. Mike London says:

    It may just be low on oil because if it’s happening when going side to side, the sending unit may detect the oil swishing around and thus putting a warning light on. But in a straight line, it doesn’t activate the light because the oil is stable.

    I’ve seen this happen in cars at least a dozen times in my years in auto service. Anyway, hope this helps.

    • Pat says:

      This happens to my car every time it is low (this actually just happened last week for the 5th time). I’d check the oil level before doing anything else…

      Engine heat might be a different issue. Maybe Mike (with his auto service background) can tell you whether low oil could cause an engine to overheat (with my limited knowledge, I would think that it could).

  3. Ottawacon says:

    At a guess, I would bet your cooling flow is impaired, likely because it is only getting partial flow. In a straight line, your actual speed is forcing enough water through to make it work, when zig-zagging the engine is working as hard or harder but the flow rate is lower. Try cleaning out the cooling passages (use monofilament, like from a trimmer).

    I hope that is not because of a milfoil invasion, for the sake of the lake.

  4. Call Bob Rae – he might be able to get it running again.

  5. jp says:

    Does not sound good to me, especially both at the same time. Did you have it serviced this year? Get out your credit card I fear.

  6. allegra fortissima says:

    BEFORE you get at the sinking part of the story:

    http://www.mercurymarine.com phone: (920) 929-5040

    And have the serial number ready. Sheesh…

  7. smelter rat says:

    It ain’t broke until the pistons come through the block 🙂

  8. W the K - No, not Warren says:

    Sell it for large. Then go get a kayak.

  9. Iris Mclean says:

    Do the temp light and oil light start and stop flashing at exactly the same time? If so, I’d suspect you are getting false warning lights. If you have a decent marina on your lake, they could do a quick and easy oil-pressure test. (Should be around 30lb at idle) If the engine is indeed overheating because of low oil pressure, you have a damaged engine. Before you feed it to the fishes, get the pressure tested, and check the cooling flow at the same time, as Ottawacon suggests. Don’t bother with Bob. He knows dick about boats. Besides, he’s on Big Rideau Lake…nowhere near you.
    I was a marine mechanic in a previous life.

  10. sounds like oil pressure…

  11. Wannabeapiper says:

    Check your water pump by looking at the discharge-a hard stream of water coming out of the back of your engine. If it is over heating the engine will start to shut down-TRUST YOUR INSTRUMENTS! Otherwise might be your oil pump-check engine oil level,
    the engine will protect itself electronically if your water pump is plugged. If you have shallow water at your dock and/or weeds they tend to foul your pump. If your engine is shutting down because of temperature the oil indicator might come on.

    I have seen this before so I speak from experience-doesnt mean I am right, but this stuff happened to me.

  12. Jan says:

    What colour is the motor – beige, taupe or grey? Apparently this can be critical.

  13. Iris Mclean says:

    Might be some confusion as to whether it’s a Mercruiser I/O or a Merc outboard.

    • Warren says:

      Mercury 150hp…and there’s no way a couple of 70lb kids in a tube could’ve overheated an engine that big!

      • Wannabeapiper says:

        Its not the load, it maybe a cooling issue-did you get it checked or repaired-I am curious about the diagnosis. I had the exact same problem and I was right but I had to take it in for repair-replaced the water pump and everything was fine. Soon after I converted to sailing-but an inboard sailboat engine has the same issues-the difference is you can sail or kedge your way to the dock, rather than scream for help………..

  14. nic coivert says:

    This may not be helpful but a boat is a hole in the water you throw money into.

  15. Pat says:

    Gord – you need to talk more about stuff that isn’t political… I genuinely enjoyed that comment of yours!

  16. Iris Mclean says:

    All this free advice must have Warren’s socks rolling up and down.

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