Skipjack 25 Fisherman Thunking when going into gear

Discussion in 'Boating Discussion' started by InDeepShip, Jul 26, 2018.

  1. InDeepShip

    InDeepShip Well-Known "Member"

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    Adam
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    My buddy has a skipjack 25 fisherman with a volvo penta and it thunks when it goes into gear. He thinks its a stretched shifter cable. He has to put it into gear and then push it forward more to get the RPMs up for it to go into gear. What do you guys think that it might be? Would you recommend replacing the shifter cable or something else?

    Edit: The thumping is pretty harsh it doesn't sound right
     
    Last edited: Jul 26, 2018
  2. plj46

    plj46 I've posted enough I should edit this section

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    My outboard "thunks" when i put it in gear.Its not like a car with an automatic transmission.Does he put it in gear quickly or try to ease the shifter ? easing it is the worst thing you can do to it.Maybe check the gear oil ?
     
  3. TEAMFISH

    TEAMFISH JUST ADD WATER

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    Could be multiple things.
    (1) Gear oil (Volvo changed to synthetic and it will make them "thump" more)
    (2) Idle too high
    (3) Forward cone
    (4) Excessive forward/reverse cone shaft play
    (5) Throttle engaging before out drive goes into gear completely
     
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  4. Derby

    Derby My "Member" is Well Known.

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    Set idle with boat in gear. That's the main root cause I have seen in the past.

    All my inboard boats thunked. Same with buddies IO. My outboards do too but it's harder to hear.
     
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  5. Derby

    Derby My "Member" is Well Known.

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    Cables may stretch over time, but not during operation. Disconnect and see if they slide smoothly. If not, they should be replaced.
     
  6. Derby

    Derby My "Member" is Well Known.

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    Sorry, one more thing. You need to use a timing light to set idle. The tachometer is not a very accurate instrument.
     
  7. salty nuts

    salty nuts Well-Known "Member"

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    I was always told a heavy thump is a good thing we going in gear...mine does that. When it's smooth that's when you could have cone clutch issues. Mine thumps hard in forward and reverse.
     
  8. TEAMFISH

    TEAMFISH JUST ADD WATER

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    Volvo's tend to thump but too much can be bad. There is a spec for acceptable play. There is a Bronze bushing at the bottom that can start to get hammered. The top nut also comes in three thicknesses to adjust end play. If that bottom bushing gets hammered too hard and decides to let loose it will send the shaft through the upper housing. Never had it happened and not saying this is the problem but it's something to consider.
    [​IMG]
     
  9. MATTANZA

    MATTANZA old man of the sea, in training.

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    check cvu
     
  10. InDeepShip

    InDeepShip Well-Known "Member"

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    Thanks for all the recommendations! Is there an idiots guide to adjusting the idle speed? He believes that this thunking is hurting the engine. Im not used to working on small boat engines so I'm new when it comes to the mechanical side of this stuff.
     
  11. mischief1

    mischief1 Member

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    May also be U Joint
     
  12. Derby

    Derby My "Member" is Well Known.

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    Depends on motor.

    Could be a little more fuel in carb idle circuit or advance the timing. You should check the manual for that motor. Or find someone that has your motor and knows what they are doing.
     

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