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89 Yamaha Pro 50-Crankshaft noise or not Crankshaft noise

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  • 89 Yamaha Pro 50-Crankshaft noise or not Crankshaft noise

    This seems somewhat complicated.

    I bought the referenced engine and had our local outboard repair person attend the initial startup.

    It had not run in about a year. The carbs obviously needed some work but that is not my most urgent concern.

    It started and ran fairly well, given the conditions stated.

    I asked the the local expert what he thought and he said it sounds like the main rod bearings are getting ready to go. The question to him was--how do you figure that?

    He said the engine was making a wooooooring sound maybe like a large fan or something like that. My ears don't seem to work in that frequency and the sound was not noticeable by me. It sounded like a typical running outboard motor with a miss here and there.

    I can return the motor and get the money back. The dilemma is the motor is mounted on the party barge along with the control box, etc.

    Question: Can failing main bearings be determined by listening to the motor run--the answer is, of course it can but this would depend on the degree of deterioration. If it is getting ready to come apart, there would obviously be noticeable noise.

    I have confidence in out local guy but I really don't know what the next step should be. We checked the compression and got 120 on all three.

    Would somebody offer some insite---please?

  • #2
    Re: 89 Yamaha Pro 50-Crankshaft noise or not Crankshaft noise

    A 20+ year old 2 stroke outboard is probably going to make some whiring and clicking noises, my 1999 makes noises. It's really hard to say if your motor is near ready to self-destruct but if it's running good maybe you should just go ahead and enjoy it and don't worry about it. My wife and I were launching the boat several years ago and I thought I heard a noise in the motor, she said the noise was mostly in my head and that I was being paranoid, and you know what, she was right! Several years later, motor still running fine! Noises in head!

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    • #3
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      Re: 89 Yamaha Pro 50-Crankshaft noise or not Crankshaft noise

      I could tell if a Snowmobile engine needed crank bearings, by listening for a rolling sound after the engine was shut down. The plastic cage would melt, and the balls would continue to turn after you shut it down.

      I could never tell if a rod bearing was on it's way out. But that was 2 cylinders. There are feq's to listen for (wish I am not sure of on a 3 cylinder Yamaha) but rod bearings? Needle Bearings, um I am a little sceptical. But not in disbelief. The needles are incased in plastic as well.

      So the next question is "Are you basically stealing the motor at the price?" Is there a reason that he may want it?

      3 cyl Yamaha's are basically Indestructable and highly saleable, If he knows the price is lower than he could resell it for, well that may be it.

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