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Mercruiser 470 outdrive

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  • Mercruiser 470 outdrive

    I have a 1982 Mercruiser 470 motor/outdrive. Motor still runs great, but 2 weeks ago my prop spun out on me. The boat would still move at idle, so I purchased a rebuilt prop to get me trough the holiday weekend. Then, after launching, I never even made it out of the cove. The prop won't spin in neither forward or reverse. I checked the prop again today, and it doesn't appear burned out, and I can spin the shaft with the drive engaged. My question, is where do I start? I am a fairly experienced mechanic, but not so much with marine issues. Do I start with the lower unit, or just pull the whole outdrive? I'm headed to get a manual this evening, but I'm just hoping for some input on diagnosing the problem.


  • #2
    Re: Mercruiser 470 outdrive

    Howdy,


    Have a look behind the engine.

    It sounds more like a spun coupler.

    Look for metal shavings or black powder near the back of the engine.

    If it's the coupler, you will be removing the engine to replace.

    Regards,


    Rick
    ----------------------------------------------------------------------------------
    I use xxx oil and have never had a problem........
    This post was created with OpenSuSE x64 Linux!

    Comment



    • #3
      Re: Mercruiser 470 outdrive

      That's not a happy thought.... I did a glance over while I was checking the prop and listening for noises, and I didn't see obvious shavings. Will have to check over again. Would I want to drain my gear oil and check for anything there?

      Comment



      • #4
        Re: Mercruiser 470 outdrive

        You could. Not a bad idea if it hasn't been done.


        On the trailer (with the key in your pocket and the coil wire removed ), have someone move the shifter into FWD while you turn the prop clock-wise.

        The drive should go into gear and you should hear (and feel) a clicking sound.

        If you try to turn the prop CCW. it should be (a lot) harder or impossible to turn (because you'll be trying to turn the engine)

        Have them move the shifter to REV while you turn the prop CCW.

        It should go into gear and you should hear similar clicking and you shouldn't be able to turn the prop CW.


        If you can turn the prop CCW while it's in FWD (no clicking) .........

        ........... (or CW while in REV) you may have a spun coupler.
        ----------------------------------------------------------------------------------
        I use xxx oil and have never had a problem........
        This post was created with OpenSuSE x64 Linux!

        Comment



        • #5
          Re: Mercruiser 470 outdrive

          Hello States,The original mercruiser manual is available for free download in the "Adults Only" section at the top of this forum. It is manual #6.

          Eric

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          • #6
            Re: Mercruiser 470 outdrive

            take the top cover off the outdrive (4 bolts) and check your upper gears. also coupler, as mentioned. the shaft going into the engine should be spinning whenever the engine's running, neutral or not. if not spinning, its the coupler. if it is, the problem is in your drive.
            '86 Glastron Conroy X-19, Merc 170
            '04 Carolina Skiff J14, 25 hp Mercury
            sigpic

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            • #7
              Re: Mercruiser 470 outdrive

              So, ok, I'll check the shaft, since the prop is off and I don't need to shift into gear, right? I just am not relishing the idea of pulling the motor since my garage is full and I don't have a cherry picker. Will I need to pull the outdrive too if that's the case? And are there any special tools needed to reinstall said drive? All I want to do is go boating! I'm not afraid of tearing into it, just want to make sure I'll have what I need to get it all back together in working order.

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              • #8
                Re: Mercruiser 470 outdrive

                That shaft Mike is referring to is visible while the drive is installed. Look behind the engine inside the boat, It goes thru the transom.

                Guys, isn't there a rubber burning smell from inside the boat if the coupler is spun?

                Comment



                • #9
                  Re: Mercruiser 470 outdrive

                  If that smell is the sign then I'm sure you guys are right. We did notice a burnt rubber smell while I was trying to limp to the dock. Or paddle. So, how much do I need to pull apart to get the motor out properly?

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                  • #10
                    Re: Mercruiser 470 outdrive

                    Hey States, IF that IS your problem you will have to pull the drive off first to remove the engine. You should download the manuals they are available for your engine as well as drive. ( 2-separate ones), detailed in this repair.

                    That manual I mentioned above is not correct- it starts at '83. (sorry)

                    Eric

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                    • #11
                      Re: Mercruiser 470 outdrive

                      Originally posted by 4states View Post
                      If that smell is the sign then I'm sure you guys are right. We did notice a burnt rubber smell while I was trying to limp to the dock. Or paddle. So, how much do I need to pull apart to get the motor out properly?

                      If you smelled burning rubber, you will also find rubber powder back there too if you look closely.

                      Plan on pulling the drive and engine in that order.

                      Downloadable manuals are at the top of the furum in the "Adults Only" sticky (permanent) message.
                      ----------------------------------------------------------------------------------
                      I use xxx oil and have never had a problem........
                      This post was created with OpenSuSE x64 Linux!

                      Comment



                      • #12
                        Sign up today
                        Re: Mercruiser 470 outdrive

                        Ok, thanks for the help... motor and drive are out and the problem was the coupler. I had a guy with more experience do the yanking, and he did a thorough check of other parts after the motor came out. Gimble bearing and shift cable seemed fine, but what caused the coupler failure was the front motor mount. It had cracked and dropped about 3/4". So, now I need to rebuild it. I'm going to cut it all out, grind back the gelcoat, then glass in a new "shelf" for the motor. My mechanic told me there isn't alot of torque on the front, and the motor just needs a solid, level place to mount. There is some rot under the glass, so I'm not sure how far I'll need to go, but I'm just wondering if this shelf I'm building will be good enough. Anyone know if just building a new mount and glassing it to existing walls will hold? I figure I'll grind back 4-6" all the way around the old area, laminate plywood together to get the shape of the old mount to fit in, and then extend fiberglass all around. Does this sound adequate?

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