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  1. #1
    Member
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    Jun 2022
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    Lower Unit Noise

    175 pro xs Serial# 1b698699
    Okay so i was on the water and hear a faint clunking sound when i was idling. I shifted to Neutral noise went away. Back to forward no noise. Fished on and ended my day. I got back to the house and proceeded to drain lower unit oil (i just replaced seals so was doing a trip then draining to make sure all the water was out) (also the water intrusion was very minimal). Anyway There were some small flakes of metal and 2 small splinters that i saw. I looked at the shift slide in it was biased toward REVERSE. I recalibrated it according to the manual. My thoughts were that the cable had stretched enough that it wasnt going into FORWARD enough. I have a tub so i refilled the lower and ran it (idle) in the tub and there was no noise. Drained again and fluid seemed okay. My question is: Is it okay to proceed to run it?

  2. Member
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    #2
    I have heard a clunking noise at idle from time to time on different engines that I have ran. I always figured this comes from the gear backlash and prop connection to prop shaft has a small amount of clearance. At idle the engine may not run perfectly smooth so you get some clunking from this.
    Last edited by hooken203; 03-18-2025 at 08:24 AM.

  3. Member
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    #3
    This may have been that. I'm not sure. This motor have never exhibited that behavior although I know what you're talking about. Ive heard it on the hose. This also wasn't like when you slow shift and outboard. It was like knock knock knock pause knock knock pause ... like kind of irregular.

  4. Member
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    Jun 2013
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    LONGVIEW TEXAS
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    #4
    clutch rattle some props can cause this
    .................................................. ...the scariest thing in life is the unknown ...................................

  5. Mercury 3L/4 Stroke/Verado Moderator EuropeanAM's Avatar
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    #5
    Can also be amplified if the propeller nut is not torqued to specifications.


    Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
    Still consider myself a "Marine Apprentice" after 48 years (learn something new every day).
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  6. Member
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    Jun 2019
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    Tulsa, Oklahoma
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    #6
    I had this issue as well a while back, my clutch dog was slipping out of position (only when in forward) as I would idle, turned out that the shift cable had stretched a little (20+ years old) and I was able to adjust it to where it engaged fully again, haven't had a problem with it since.

  7. Member lpugh's Avatar
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    May 2009
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    Sacramento Ca
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    #7
    cables do not stretch! shifter do wear over time, cups for the Barrell adjuster get lost, shift lever rods get bent
    Thank You Leon Pugh

  8. Mercury 3L/4 Stroke/Verado Moderator EuropeanAM's Avatar
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    #8
    I'll have to respectfully disagree on cables "stretching". Whether it's the guide wearing, spring windings of the guide compressing, or the wound insert growing in length, the overall result is a cable that is longer than it's initial adjustment.

    All of the other linkage items (including those mentioned) occur quite often as well.


    Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
    Still consider myself a "Marine Apprentice" after 48 years (learn something new every day).
    Mercury Parts, Mercury Outboards, Smartcraft & Accessories, Injector Service, TDR Reeds- BBC Sponsor

  9. Member
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    May 2024
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    Dover, New Hampshire
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    #9

    dog lashing video - Opti 150 2014 w/ ultra low hours.

    Same- so we can't All be having a bad gear box? video section one, is past the clear and obvious dog latch with plenty of forward lever remaining, (sorry no detailed video, it was just me) then a couple of seconds of forward thrust, past the first throttle "hump" = no noise. https://youtube.com/shorts/1ye83gD1c3k?feature=share