315 Yanmar problem

Discussion in 'Mechanic's Corner' started by Howsounder, Feb 7, 2021.

  1. Howsounder

    Howsounder Active Member

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    52 nautical mile, new to me delivery trip home went well Sunday. Really rough crossing of the Georgia straight where for learning purposes, I ran into, down wind, and across the sizeable chop. Slowed down too, but this 27 mackinaw was much more stable at 20 knots. What a blast. When coming into dock, every time I shifted into neutral, I got a pretty weird and pretty loud noise, very much like a bilge pump sucking air. As soon as I shifted into forward, or reverse, it stopped immediately. I got docked, and turned off the engine, and opens the engine hatch and got smoke, and a horrible clutch/brake smell.

    Today I checked the transmission fluid, and found it full, not smelly, and clear. Turned the engine, and shifted from neutral, forward and reverse, and got no funny noises, and proper engagement in and out of gear..........any thoughts?
     
  2. seatux

    seatux Well-Known Member

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    Go to Harbor Freight and buy one of those cheap laser temp units. then take the boat out and run it hard again, checking every once in a while for the source of smoke and or smell but especially using that laser temp gauge...it should isolate the issue, may not tell you the problem , but should isolate where it is coming from.
    Other than that, I have nothing for you, Sorry.
    But do let us know what you find! I have twin Yanmars, but have Never experienced anything like this!
     
  3. Howsounder

    Howsounder Active Member

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  4. Howsounder

    Howsounder Active Member

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    Thanks for this. I have a non contact thermometer, and plan on doing this. My gut on this was that while in gear there was nothing untoward going on, so probably no elevated temps. Today, no funny noise when in neutral. I plan to have a three foot length of hose handy, so I can put one end to my ear, and point and probe with the other end, to isolate, and therefore identify where the noise is coming from.

    steve
     
  5. pilarboat

    pilarboat Well-Known Member

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    Seatux: Could this have anything to do with the trolling gear?
     
  6. Howsounder

    Howsounder Active Member

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  7. Howsounder

    Howsounder Active Member

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    I am not sure I have a trolling valve on this boat. No controls for it at the helm, so probably don’t have one. I did take the boat out armed with a temp gun, and a 3 foot length of garden hose so I could put one end to my ear if the problem occurred, and be able to localize the sound. Got the engine up to temp, in and out of gear, no sounds, no issues, no smells or smoke. Did find I could do up to 4.8 knots with the 9.9 high thrust outboard, and recorded the following performance data:


    1250 5.8 knots, just less than 1 usgph

    1500 6.52 1.5 usgph

    1750 7.25 2.6 gph

    2000 7.82 knots 3.25 gph

    2250 9 knots 4.75gph

    2750 16.5 knots 8.5 usgph

    3000 19.8 Knots 9 usgph

    3200 22 knots 10 usgph
     
  8. seatux

    seatux Well-Known Member

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    I don't have a trolling gear, so I cant speak with confidence to that issue.
     
  9. Howsounder

    Howsounder Active Member

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    I found the problem! The ignition switch is dodgy.......sometimes it does not return all the way back to ignition from “crank” or “start” position. Sensors turn it off in forward or reverse, but in neutral it was turning over the starter motor. (DANG!) Oiled up the ignition switch and it’s returning reliably to ignition position. I think after the thrashing this has given my starter, I should probably order one........probably 1500 bucks!
     

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