Announcement

Collapse
No announcement yet.

Reinstalled OMC cobra sterndrive...Help!-gctid385261

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

    Reinstalled OMC cobra sterndrive...Help!-gctid385261

    I just reinstalled my OMC Cobra stern drive unit for the season, all went well but I am looking for some way to reinsure I aligned the shift linkage correctly. In neutral the prop spins freely, in reverse it spins freely, but in forward the prop spins but there is a popping sound every half revolution...is this normal?

    1989 bayliner capri cuddy

    5.7 liter

    Matt

    #2
    There is no real shift linkage alignment when installing the drive - the lever just has to go in the notch. No alignment should have changed removing and reinstalling.

    The noise you hear is the dry water pump impeller turning

    Comment


      #3
      The Cobra is a Dog Cluth gear engagement drive.

      The sea water pump impeller does not spin until the engine is running.

      What you are hearing is likely the Dog Clutch engagement teeth clicking between the sliding sleeve and the two driven gears.

      You may hear this while the sliding sleeve is not quite centered in the neutral position on the prop shaft.

      .
      Rick E. Gresham, Oregon
      2850 Bounty Sedan Flybridge model
      Twin 280 HP 5.7's w/ Closed Cooling
      Volvo Penta DuoProp Drives
      Kohler 4 CZ Gen Set

      Comment


        #4
        The only time the prop should spin freely is in neutral. Did you disconnect the lower shift cable when you removed the drive ?

        Comment


          #5
          Try bumping your starter a few revs. Not to start it but to turn it, then see what happens. I don't think you can properly shift it with the engine off.

          Its been a long time for me and I may be wrong.

          Doug
          Started boating 1955
          Number of boats owned 32
          Bayliners
          2655
          2755
          2850
          3870 presently owned
          Favorite boat. Toss up. 46' Chris Craft, 3870 Bayliner

          Comment


            #6
            To clarify. the prop spins right and left in neutral, spins in one direction only in reverse, and the othe direction in forward. I did forget to mention there is no gearcase lube in it yet.

            Comment


              #7
              Stuart Hastings has compiled the defacto bible on OMC drives you can read on the link below or search the web it may assist http://cdnbaylinerownersclub.com/ind...ch-info-part-1

              Comment


                #8
                mboat wrote:
                To clarify. the prop spins right and left in neutral, spins in one direction only in reverse, and the othe direction in forward. I did forget to mention there is no gearcase lube in it yet.
                Correct, and you will hear the ratcheting sound as with any Dog Clutch gear engagement out drive.

                The dog teeth are bevel cut... or "ramped" so to speak......, and are intended to hold under one direction of rotational force ONLY, as there is no coast force applied towards the engine.

                This is the nature of the Dog Clutch style engagement.

                Even the older motorcycle transmissions, old school machinery, farm equipment, etc., used a similar engineering...., but with the dog tooth cut in favor of holding in either direction of rotational force.

                .
                Rick E. Gresham, Oregon
                2850 Bounty Sedan Flybridge model
                Twin 280 HP 5.7's w/ Closed Cooling
                Volvo Penta DuoProp Drives
                Kohler 4 CZ Gen Set

                Comment


                  #9
                  "5 Steps of the Engine Shift Bracket Adjustment"

                  1. Forward Overstroke Adjustment

                  Center the cable anchor located in the angled slot on the top of the shift lever. Install the remote control shift cable, control box in FORWARD GEAR FULL THROTTLE. Pull out on the casing guide to remove any slack. Ajust the shift cable trunnion to center the forward (fixed) overstroke cam with the switch button on the overstroke switch.

                  2. Forward Gear Engagement

                  Install the transom bracket shift cable, control box is still in forward gear full throttle. PULL OUT ON THE TRANSOM BRACKET SHIFT CABLE TO FULLY ENGAGE THE CLUTCH DOG WHILE SOMEONE ROTATES THE PROPELLER. Make sure you pull back on the shift cable to remove all the end play from the system as you adjust the black barrel trunnion. When installed correctly and all slack is out of the system the load lever will "rock upward stiffly" and "rock downward easily"but should always center itself!

                  3.Reverse Gear Engagement

                  Shift the control box into REVERSE GEAR FULL THROTTLE, loosen the 7/16" nut in the angled slot at the top of the shift lever on the shift bracket. PUSH DOWN on the shift lever while someone rotates the propeller to FULLY ENGAGE THE CLUTCH DOG. While holding down on the shift lever, remove all slack from the remote control shift cable by pulling its casing guide to the rear of the boat. Be careful not to preload the system. Then tighten the 7/16" nut securely. When adjusted properly, and all play removed, the load lever will "rock downward stiffly" and "rock upward easily", but will always center itself.

                  4. Reverse Overtroke Adjustment

                  Adjust the reverse overstroke cam to center itself with the switch button on the overstroke switch (3/8" nut). The control box is still in reverse gear full throttle. "PW thru RG" (sic) models will probably not have a reverse overstroke cam.

                  5. Throttle Cable Adjustment

                  Install and adjust the throttle cable. Control box should be moved into the forward gear idle position, then half-way back to neutral. Tension on the cable should be only enough to positively close the throttle plates. Excessive tension will cause the shift system to bind. (Unit should shift no harder with the cable installed than with it removed).

                  Now run the unit and check for smooth positive shifting, also check for proper operation of the ESA system by making the running checks at the engine shift bracket! Service Kits are available to upgrade the ESA module to the latest pulse pattern, time duration and RPM limits (SB #4099).

                  Comment


                    #10
                    2850Bounty wrote:
                    The Cobra is a Dog Cluth gear engagement drive.

                    The sea water pump impeller does not spin until the engine is running.

                    What you are hearing is likely the Dog Clutch engagement teeth clicking between the sliding sleeve and the two driven gears.

                    You may hear this while the sliding sleeve is not quite centered in the neutral position on the prop shaft.

                    .
                    Sorry, I missed something here in that the drive is installed, but so did you in your explanation

                    With the drive in gear, as you can imagine the dog clutch is "connected" making the driveline between the prop and the shaft to the engine have a solid connection. This shaft is what drives the water pump, it is on the other side of the dog clutch from the prop but when in gear those two halves are connected, which is what transmits power. So, put it in gear and manually turn the prop and the water pump turns.

                    BUT, what I screwed up is I was thinking the drive was not attached and you were shifting at the linkage. If the drive is on the engine, the same principal applies, except you would have to exert so much force on the prop to actually turn the engine of course... so it's not practical. But try the drive prior to installation and of course the water pump is then driven. This is important as when you have it off and you spin it in gear, you'll hear a somewhat scary sounding noise... but its not your gears, it's the dry water pump. NOT relevant to the OP's question if it was tested ON the boat and I apologize.

                    The Cobra shifts fine with the engine NOT running/etc. and will solidly engage the gear, no problem. But where the issue occurs in troubleshooting is if you try and spin the prop in the opposite direction of what it's supposed to in that gear... in forward, the clutch may only engage if you spin the prop in the right direction.... same with reverse. Because spinning it the "wrong" way would cause the opposite sides of the dog clutch teeth to match up, which does not happen in "real life" as the engine spins in only one direction. (Unless something goes gravely wrong.)

                    There is still no "alignment" of the shift mechanism when removing/installing the drive, either the lever end is in the notch or not.

                    I believe the same is true even if you have a Volvo masquerading as a Cobra, like this fine Penta SX below which clearly shows it's Cobra origins


                    Comment


                      #11
                      ishiboo wrote:
                      Sorry, I missed something here in that the drive is installed, but so did you in your explanation
                      • 1 wrote:
                      • With the drive in gear, as you can imagine the dog clutch is "connected" making the driveline between the prop and the shaft to the engine have a solid connection.
                      • This shaft is what drives the water pump, it is on the other side of the dog clutch from the prop but when in gear those two halves are connected, which is what transmits power. So, put it in gear and manually turn the prop and the water pump turns.
                      • BUT, what I screwed up is I was thinking the drive was not attached and you were shifting at the linkage. If the drive is on the engine, the same principal applies, except you would have to exert so much force on the prop to actually turn the engine of course... so it's not practical. But try the drive prior to installation and of course the water pump is then driven. This is important as when you have it off and you spin it in gear, you'll hear a somewhat scary sounding noise... but its not your gears, it's the dry water pump. NOT relevant to the OP's question if it was tested ON the boat and I apologize.
                      • The Cobra shifts fine with the engine NOT running/etc. and will solidly engage the gear, no problem. But where the issue occurs in troubleshooting is if you try and spin the prop in the opposite direction of what it's supposed to in that gear... in forward, the clutch may only engage if you spin the prop in the right direction.... same with reverse. Because spinning it the "wrong" way would cause the opposite sides of the dog clutch teeth to match up, which does not happen in "real life" as the engine spins in only one direction. (Unless something goes gravely wrong.)
                      • There is still no "alignment" of the shift mechanism when removing/installing the drive, either the lever end is in the notch or not.
                      • I believe the same is true even if you have a Volvo masquerading as a Cobra, like this fine Penta SX below which clearly shows it's Cobra origins



                      • 1 wrote:
                      • It is a "solid" connection in one rotational direction only.
                      • In looking at an OMC Cobra upper unit schematic, I'd have to suggest that the main drive gear (actually SEQ #38) is what drives the impeller pump..... not the vertical shaft as with the Merc A drive. Yes/No?

                        The shaft assembly (SEQ #34) is fixed to the engine drive coupler.

                      • I too was assuming that the drive was installed.

                        When installed, there's no way you are going to turn the vertical shaft by the propeller...... let alone the main drive gear that is coupled to the engine.

                        Volvo Penta, or the SX Cobra cone clutch drive.... Yes, we can turn the prop and rotate the vertical shaft as well as the sliding sleeve!
                      • I would have figured the same... pretty much like the Merc A drive.
                      • That is good to know for the OMC guys.
                      • Volvo masquerading itself as a Cobra?????

                        Volvo Penta has always used their patented cone clutch gear engagement with the transmission being in the upper unit.

                        Where as the Dog Clutch drive gear selection is done in via lower unit.

                        Apples/Oranges.

                        Hyjack on my own post here.

                        I will say that OMC did something rather unique with the King Cobra "cone clutch" drive sea water pump.

                        They engineered a fourth "driven gear" (SEQ #8) in the transmission as an idler gear, and used this gear to drive the sea water pump. Pretty clever!



                        KC CC drive cut view.

                        Note the fourth gear and the sea water pump.





                      .
                      Rick E. Gresham, Oregon
                      2850 Bounty Sedan Flybridge model
                      Twin 280 HP 5.7's w/ Closed Cooling
                      Volvo Penta DuoProp Drives
                      Kohler 4 CZ Gen Set

                      Comment


                        #12
                        2850Bounty wrote:
                        • 1 wrote:
                        • It is a "solid" connection in one rotational direction only.
                        • In looking at an OMC Cobra upper unit schematic, I'd have to suggest that the main drive gear (actually SEQ #38) is what drives the impeller pump..... not the vertical shaft as with the Merc A drive. Yes/No?

                          The shaft assembly (SEQ #34) is fixed to the engine drive coupler.
                        • I too was assuming that the drive was installed.

                          When installed, there's no way you are going to turn the vertical shaft by the propeller...... let alone the main drive gear that is coupled to the engine.

                          Volvo Penta, or the SX Cobra cone clutch drive.... Yes, we can turn the prop and rotate the vertical shaft as well as the sliding sleeve!
                        • I would have figured the same... pretty much like the Merc A drive.
                        • That is good to know for the OMC guys.
                        • Volvo masquerading itself as a Cobra?????

                          Volvo Penta has always used their patented cone clutch gear engagement with the transmission being in the upper unit.

                          Where as the Dog Clutch drive gear selection is done in via lower unit.

                          Apples/Oranges.

                          Hyjack on my own post here.

                          I will say that OMC did something rather unique with the King Cobra "cone clutch" drive sea water pump.

                          They engineered a fourth "driven gear" (SEQ #8) in the transmission as an idler gear, and used this gear to drive the sea water pump. Pretty clever!



                          KC CC drive cut view.

                          Note the fourth gear and the sea water pump.




                        .
                        Yes, as I said I had originally thought the drive was NOT attached to the boat, which is why "The sea water pump impeller does not spin until the engine is running." confused and is not really the case

                        "Volvo masquerading itself as a Cobra" was a Volvo SX pictured which at first glance appeared to be an OMC... my point was that even if it's NOT a Cobra but an SX which you are more familiar with, it would still be the same - removing and reinstalling the drive alone should not cause an "alignment" issue with the shift mechanism... that is all. I never said anything about the invention order of anything :P

                        Comment

                        Working...
                        X