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Prop Problems??

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  • Prop Problems??

    I have a 25 Horse Johnson outboard that I’m pretty sure the prop bushing has gone out in it. Have any of you guys had luck pressing a new bushing in the old prop, or should I just buy a new prop?
    I know I’ve tried pressing new rubber bushings into drag-links on 18 wheelers with no luck; much easier to just buy new drag-links with the bushings installed. Wondering if the same applies to outboard props?
    Not as Lean, Not as Mean, but still a Marine!

    If there must be trouble, let it be in my day, that my child may have peace. -- Thomas Paine

  • #2
    No, a new prop won't do it. Pull the one that's on it now, and wiggle the shaft. If there's any radial play, there may be a bad seal or bearing. While you're at it, change the lower unit oil.
    -Remote locations are cheap insurance.
    -There are two kinds of ships: Submarines and targets

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    • #3
      ghrit, Nothing wrong with the lower unit all is good and tight and full of oil.

      Let me see if I can explain the problem a little better. In gear, at high idle all is good........at half throttle or above the RPM’s rev up but the boat doesn’t get any faster, kind of like a clutch slipping in a manual transmission.
      Not as Lean, Not as Mean, but still a Marine!

      If there must be trouble, let it be in my day, that my child may have peace. -- Thomas Paine

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      • #4
        There is a rubber bushing/donut inside the prop itself, assume that is what you are talking about. If that slips it acts like you say. However the rubber quickly wears out totally; and then it will not get up to even half speed.....it only gets worse. The rubber is to save the prop IF you hit something, and it dampens vibration.

        The rubber hub/bushing can be pressed out and replaced. You need a heavy duty press.

        However many people use a replacement/universal bushing replacement model. It is slightly undersized and you use a larger thrust washer and the prop nut to squezze the undersized rubber bush to forcibly contact the hub. I'd not do this on a large 300 hp motor; but would be OK on your 25 hp. WestMarine and others carry these kits.

        rubber hubs usually wear out because of extensive running hard in heavy weeds or in sand.
        Last edited by BEAR; 07-10-2018, 03:51.

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        • #5
          Originally posted by BEAR View Post
          There is a rubber bushing/donut inside the prop itself, assume that is what you are talking about. If that slips it acts like you say. However the rubber quickly wears out totally; and then it will not get up to even half speed.....it only gets worse. The rubber is to save the prop IF you hit something, and it dampens vibration.

          The rubber hub/bushing can be pressed out and replaced. You need a heavy duty press.

          However many people use a replacement/universal bushing replacement model. It is slightly undersized and you use a larger thrust washer and the prop nut to squezze the undersized rubber bush to forcibly contact the hub. I'd not do this on a large 300 hp motor; but would be OK on your 25 hp. WestMarine and others carry these kits.

          rubber hubs usually wear out because of extensive running hard in heavy weeds or in sand.
          What he ^^ said. Most wear out due to age or impact with a log or rock.
          Some good prop shops replace the bushing, but on a 25HP Johnson, buying a new prop will probably be a better deal.
          My money is on a little harder than a drag link to do.

          ETA: I'm not a fan of the "squeeze it with the prop nut" crowd.
          Wimachtendienk, Wingolauchsik, Witahemui

          He who knows not and knows not that he knows not, is a fool.
          He who knows not and knows he knows not, is wise.

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          • #6
            Thanks fellas!
            Upon further inspection and doing a little more research, I’ve found the prop to be a stainless steel Power-tech brand, so I believe it’ll be worth repairing. Power-tech just happens to be down the road from me in Shreveport, LA. I’ll give them a call tomorrow and see if they will let me drop it off and have them install a new bushing.

            You guys know your stuff.....it was a stump that got it! We were fishing Lake Erling, the number 1 bass fishing lake in Arkansas. It’s also got stumps as thick as hair on a dogs back.
            Not as Lean, Not as Mean, but still a Marine!

            If there must be trouble, let it be in my day, that my child may have peace. -- Thomas Paine

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            • #7
              One stump usually doesn't do it, it was made for that shock. Probably a number of slip/shock events and that last one was the "straw" that broke the camel's (prop) back. Shallow running takes its toll.

              Power tech should be able to press in a new one. For me the tough part is getting the old one out!

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              • #8
                Originally posted by Snuffy View Post
                Thanks fellas!
                Upon further inspection and doing a little more research, I’ve found the prop to be a stainless steel Power-tech brand, so I believe it’ll be worth repairing. Power-tech just happens to be down the road from me in Shreveport, LA. I’ll give them a call tomorrow and see if they will let me drop it off and have them install a new bushing.

                You guys know your stuff.....it was a stump that got it! We were fishing Lake Erling, the number 1 bass fishing lake in Arkansas. It’s also got stumps as thick as hair on a dogs back.
                Most of the time what Bear describes is correct, but the rubber hub replaced to old shear pins and is meant bto fail at some stress level. It is possible to crater the hub in one whack, just not probable. It's a shock absorber., over enough time, simply shifting from neutral to forward or reverse will take it's toll. We've had customers who ran props for years on large OB or IO engines without hitting anything and one day while simply shifting to forward and pulling up a skier the hub will spin.

                Crip back to the dock at headway speed and get it fixed.......
                Wimachtendienk, Wingolauchsik, Witahemui

                He who knows not and knows not that he knows not, is a fool.
                He who knows not and knows he knows not, is wise.

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                • #9
                  I bought the boat and motor used about 3 years ago. The motor is a ‘93 Model, but that doesn’t mean the prop is that old, or it could be, I don’t really know. I’m betting it was a combo of age and hitting that stump though.
                  Not as Lean, Not as Mean, but still a Marine!

                  If there must be trouble, let it be in my day, that my child may have peace. -- Thomas Paine

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