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Omc cobra no forward or reverse

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    Omc cobra no forward or reverse

    I have a 2556 with omc cobra drive. Was running 25mph and popped out of gear no grinding noise or humming just have nothing now no forward or reverse. I'm new to outdrive but have mechanical skill so would like to try to tackle this without a shop. Disconnected lower shift cable tried by hand and motor stalled. I'm in the dark any help would be greatly appreciated

    #2
    The coupler maybe went. Look behind the engine, in the bilge see small rubber pieces, smells like burnt rubber.
    Be good, be happy, for tomorrow is promised to no man !

    1994 2452, 5.0l, Alpha gen. 2 drive. Sold ! Sold ! Sold !

    '86 / 19' Citation cuddy, Merc. 3.0L / 140 hp 86' , stringer drive. Sold ! Sold ! Sold !

    Manalapan N.J

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      #3
      Have you checked the gear oil level? There are number of causes for this, the cheaper ones are a shift cable that slipped out of adjustment or broke......

      Did Someone change the gear oil recently?
      88 Four Winns 200 Horizon 4.3 OMC
      98 Jeep Grand Cherokee 4.0/Selectrac
      07 Jeep Grand Cherokee 5.7 Hemi/Quadradrive II

      Long Island Sound Region

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        #4
        Welcome to the forum.

        Have you tried spinning the prop by hand with it in neutral?

        If it is instantly stalling when shifting it could be something in the lower unit is seized. If this is the case the stall will be instant and rather violent, shaking the whole boat.

        As Chief mentioned it could also be the coupler.
        Joel
        1987 3818 Hino 175
        "Knotty Girl"
        Prince Rupert B.C.

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          #5
          I hope you are able to get it fixed that happened to me popped out of gear a few times couldn't find anybody to repair it here where I live bought a replacement from crowley marine .com

          there is a few mechanics that know how o work on them good luck
          1988 flybridge trophy bayliner 2556 ,mercury 5.7 lit. OMC cobra out drive 76 hrs. on new package,
          located in ketchikan ak,name DOMINION

          Comment


            #6
            usually, but not always, if the drive coupler comes apart, there is a residual drag on the outdrive that can turn the prop, but only passively, so it wont push the boat along,, the same symptoms as with the rubber hub in the prop... but with one exception, Ive never seen a failed drive hub that didnt smell like burnt rubber, whereas you wont notice a smell from a failed prop hub. can you see the prop slowly turning when its in gear?

            with the engine OFF, have you checked to see if you could turn the prop by hand while in gear, how about in neutral?... Is the prop still on the prop shaft?... if the nut comes off, the prop will to, then you will have nothing. but even then, when shifting, you should feel it click into gear or a slight thump... unless the drive shaft or upper gear pack is broke..

            when I bought my boat, I asked around about the dependability of the cobra drives, and the local omc shop here said that the older ones were prone to jumping out of gear, and that a full failure was possible... the mechanic said that an upgrade gear set was available to cure the problem.

            I have no experience with the "jumping out of gear" problem other than what I have been told, but I have spun hubs out of props, broken u-joints and had drive hub failures, and all of them will prevent the engine from propelling the boat.


            NU LIBERTE'
            Salem, OR

            1989 Bayliner 2556 Convertible
            5.7 OMC Cobra - 15.5x11 prop
            N2K equipped throughout..
            2014 Ram 3500 crew cab, 6.7 Cummins
            2007 M-3705 SLC weekend warrior, 5th wheel
            '04 Polaris Sportsman 700 -- '05 Polaris Sportsman 500 HO
            Heavy Equipment Repair and Specialty Welding

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              #7
              Hoping to get into it on the next few weeks will try to repost with what I find. Leaning towards shift cable but we'll see thanks for all replies much appreciated

              Comment


                #8
                If you were in gear and it, by itself, just stopped propelling the boat while the engine is still running, then it can't be the shift cable/alignment because the drive would simply remain in gear when the cable disengages. I would suspect that you have a prop spin; the coupling between the shaft and the prop is broken/worn and whereas the shaft turns, the prop doesn't. You can tell if the drive is going in/out of gear if, while the engine is running, you move the lever forward or back; You should hear the very recognizable "clunk" of the drive going in/out of gear. Also, as you move the arm from forward/reverse position to the reverse/forward direction you should sense the engine speed coming down momentarily as the lever passes through the neutral position. This is by design since you can not disengage the gear while it is under load, running at higher rpm.
                Retired, computer expert / executive
                Bayliner 285 Cruiser / Mercruiser QSD 4.2L 320 HP Diesel
                Live in the Bay Area, CA, USA, boat in Turkey
                D-Marin @ Turgutreis in Bodrum/Turkey
                [email protected]
                [email protected]

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                  #9
                  I just found that it is more than likely the drive coupler. Went to winterize and put on lift til spring and the impeller isnt spinning im thw drive i had to winterize thru the circulator pump on the motor. Well see in the spring whats going on my marina doesnt have room on land for me at this point so im done for the winter.i will post back with results when i get it apart

                  Comment


                    #10
                    Originally posted by Zack View Post
                    I just found that it is more than likely the drive coupler. Went to winterize and put on lift til spring and the impeller isnt spinning im thw drive i had to winterize thru the circulator pump on the motor. Well see in the spring whats going on my marina doesnt have room on land for me at this point so im done for the winter.i will post back with results when i get it apart
                    Bit concerned that you didn't get that horrible stink of burning rubber. Seems a bit odd. However, your powers of deduction are now in gear. Does anyone have a short list of physical checks that can be made once the boat is on blocks or trailer. It would be nice to localise the fault a little before "serious" engineering has to start. I'd really hate to find out something simple has gone wrong although I can't think what it might be. Maybe someone can donate a copy of the outdrive manual (if you haven't got one yet). I only have the Mercruiser manual.
                    Terry (Retired Diving Instructor and Part Time IT Consultant)
                    1998 Bayliner 2452. 5.7l V8 - Edelbrock 1409 4bbl - Alpha1Gen2 - Solent UK.
                    MMSI 235061726

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                      #11
                      Remove the impeller housing., ground high tension lead from ignition coil. Then have someone crank over the engine while you watch the stub that comes out of the rear of the upper gear housing that turns the impeller. If this is not turning, and the engine is then yes, the coupler is probably blown. The only other thing that can cause this is if the u-joints catastrophically failed but they would be making one heck of an awful noise if that had happened. If the coupler is blown, pull the outdrive and look inside the gimble housing. Post up pix of what you see.....
                      88 Four Winns 200 Horizon 4.3 OMC
                      98 Jeep Grand Cherokee 4.0/Selectrac
                      07 Jeep Grand Cherokee 5.7 Hemi/Quadradrive II

                      Long Island Sound Region

                      Comment


                        #12
                        Originally posted by 88fourwinns View Post
                        Remove the impeller housing., ground high tension lead from ignition coil. Then have someone crank over the engine while you watch the stub that comes out of the rear of the upper gear housing that turns the impeller. If this is not turning, and the engine is then yes, the coupler is probably blown. The only other thing that can cause this is if the u-joints catastrophically failed but they would be making one heck of an awful noise if that had happened. If the coupler is blown, pull the outdrive and look inside the gimble housing. Post up pix of what you see.....
                        I would be a little concerned that if there was still some coupler friction the stub might still turn even if the coupler is shot. That would give a false positive and mislead.
                        Terry (Retired Diving Instructor and Part Time IT Consultant)
                        1998 Bayliner 2452. 5.7l V8 - Edelbrock 1409 4bbl - Alpha1Gen2 - Solent UK.
                        MMSI 235061726

                        Comment


                          #13
                          Just seeing everyones post sorry have been busy im on a lift for the remainder of the winter i will post what i find in march when there is room on land in my marina. Thanks for all the input

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                            #14
                            I found the problem. Sorry i havent posted all summer we Have been boating lol. the coupler was completely smoked. So i replaced the coupler gimbal bearing bellows gaskets shift cable and impeller and havent had a problem

                            Comment


                              #15
                              Not bad for my fist time.
                              Be good, be happy, for tomorrow is promised to no man !

                              1994 2452, 5.0l, Alpha gen. 2 drive. Sold ! Sold ! Sold !

                              '86 / 19' Citation cuddy, Merc. 3.0L / 140 hp 86' , stringer drive. Sold ! Sold ! Sold !

                              Manalapan N.J

                              Comment

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