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Possible power loss, Cruising then random RPM rising with no movement-gctid386128

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    Possible power loss, Cruising then random RPM rising with no movement-gctid386128

    I've been on my boat all weekend, and took it out 3 days in a row, with no major long hauls. Just a few short trips here and there.

    Yesterday, I made a ~30 mile round trip with my boat, cruising at around 23-25 knots there and back.

    Trip there, no problem. Trip back, problem.

    I was cruising and it almost seemed like I had hit something (this was at 10pm at night), so I stopped the boat. After mildly freaking out, I checked the prop.. just fine. Checking all the levels, engine bay, gauges. Everything was perfectly normal. Doesn't mean that everything is though. I go ahead and put it back in gear and get up to WOT with luck.. thinking maybe I just hit a small log that was slightly submerged.

    After about 10-15 minutes, it did it again.. except I didn't take it out of gear, I left it at cruising. However, the boat slowed down, but I was still in gear and the RPM's were still high. With my past experience with engines in cars, this sounds like the clutch is slipping? or the gears? I know that is not the case because I don't have a way to shift and a clutch to have slipped, but it seems as if the gears are slipping? If that's even possible.

    This would only happen at high RPM's, and when I was at WOT. I decided to slow down ~6-8 knots, and drive back. It did fine on the way back with no issue. Even backing into the dock and parking the boat in the slip wasn't a problem either. No strange smells, or noises.

    If anyone can shed some light, I would greatly appreciate any help. Since I'm not very mechanically inclined, I will most likely have to take it to a mechanic or have the mechanic on duty come out to the boat, but I was hoping to be a little more prepared.

    Here are the specs to help you better understand my issue:
    • 2002 Ciera 2655
    • Mercruiser 5.0 260 hp
    • Alpha 1 Outdrive
    • 15P Prop




    #2
    Spun hub (the rubber insert) in your propeller,,,, easy fix at prop shop.
    "Adios Dinero"
    1997 3988 with new 330 Cummins
    Photo Credit: Whiskywizard

    Comment


      #3
      Your prop hub is probaly slipping

      Comment


        #4
        jamie mac wrote:
        Your prop hub is probaly slipping
        I'll have to check that when I get back to the Marina.

        Is there anything else I can check in case it may not be that? Thanks guys!

        Comment


          #5
          Sometimes it's very difficult to distinguish sounds when running up on step.

          Could this have been an engine misfire?

          I'd say with confidence, that this was not a gear nor a drive coupler slipping. These will either fail completely, or will work.

          Prop hubs will usually fail more consistantly than a one or two time event....... , but never say never.

          Install your "like" spare prop, run it and see if it will re-occur.

          Are you aware that running at WOT RPM is not recommended for anything more than testing?

          .
          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


            #6
            2850Bounty wrote:
            Sometimes it's very difficult to distinguish sounds when running up on step.

            Could this have been an engine misfire?

            I'd say with confidence, that this was not a gear nor a drive coupler slipping. These will either fail completely, or will work.

            Prop hubs will usually fail more consistantly than a one or two time event....... , but never say never.

            Install your "like" spare prop, run it and see if it will re-occur.

            Are you aware that running at WOT RPM is not recommended for anything more than testing?

            .
            That was my plan - to install a new hub and go from there.

            No, I wasn't aware that running WOT RPM is not recommended. I hadn't planned on doing it the whole time (there are several 4-5 no wake zone's throughout the trip). My WOT RPM is only 4k anyways.. I might get 4300 without anyone on the boat.

            Comment


              #7
              2850Bounty wrote:
              Sometimes it's very difficult to distinguish sounds when running up on step.

              Could this have been an engine misfire?

              I'd say with confidence, that this was not a gear nor a drive coupler slipping. These will either fail completely, or will work.

              Prop hubs will usually fail more consistantly than a one or two time event....... , but never say never.

              Install your "like" spare prop, run it and see if it will re-occur.

              Are you aware that running at WOT RPM is not recommended for anything more than testing?

              .
              might be the beginning of prop slippage easiest thing to check with little expense if this doesnt work then as rick suggest could be moter related. . 4000 rpms seems a little low imo may be overpropped anyway.

              Comment


                #8
                jamie mac wrote:
                might be the beginning of prop slippage easiest thing to check with little expense if this doesnt work then as rick suggest could be moter related. . 4000 rpms seems a little low imo may be overpropped anyway.
                what do you mean by 'overpropped' ? and by prop slippage, you mean the hub.. correct? Just clarifying.

                Comment


                  #9
                  Jay, see your owner's manual, and look up your spec'd WOT RPM. I can tell you for certain that 4k rpm is not correct.

                  This does not lead you to the problem per se', but this should be addressed, IMO.

                  Knowing your WOT RPM is as important as are the other important aspects of boat owership.

                  .
                  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


                    #10
                    jaywoodz wrote:
                    what do you mean by 'overpropped' ? and by prop slippage, you mean the hub.. correct? Just clarifying.
                    Prop slippage is your hub.overpropped is if your prop is larger than what is actually require . i just thought your wot was a little low .previous owner may have changed prop for any number of reasons. ask your prop shop they shouldd be able to tell you.

                    Comment


                      #11
                      jamie mac wrote:
                      Prop slippage is your hub.overpropped is if your prop is larger than what is actually require . i just thought your wot was a little low .previous owner may have changed prop for any number of reasons. ask your prop shop they shouldd be able to tell you.
                      I think this is the same prop that came with the boat, I'm not too sure. About being overpropped, I have a very small amount of room from the fins of the prop and where the outdrive are. I mean.. less than an inch.

                      Comment


                        #12
                        I didnt mean for you to get overly concerned about you being over propped but if your prop ends up that it is slipping and you have to get a new one you might c heck if it is the right one for your needs. i didnt mean to go off topic.

                        Comment


                          #13
                          Went today and changed the hub with grooves. The grooves were slightly rounded but I don't think it was that bad. I switched it out and took it out.

                          I couldn't get above 12 knots at wot.. very annoying. If i raised the prop at all while cruising, the rpm's went higher and we slowed down. I ended up turning around and heading back to the slip.

                          Any ideas? It doesn't ever plane out and it just seems like its at a stand still.

                          Comment


                            #14
                            jaywoodz wrote:
                            Went today and changed the hub with grooves. The grooves were slightly rounded but I don't think it was that bad. I switched it out and took it out.

                            I couldn't get above 12 knots at wot.. very annoying. If i raised the prop at all while cruising, the rpm's went higher and we slowed down. I ended up turning around and heading back to the slip.

                            Any ideas? It doesn't ever plane out and it just seems like its at a stand still.
                            What drive do you have on there??

                            Comment


                              #15
                              Keep in mind, I didn't replace the black hub piece. I think it's plastic.. I replaced the metal piece that has grooves that you first see when looking at the prop while on the boat.

                              Comment

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