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    #31
    Originally posted by ksanders View Post

    On my 3488 with 330 Cummins engines I had the exact symptom the OP described, or close.

    I would apply throttle and the engines would both go to around 1700-1800 RPM. Then only one would advance. Increasing throttle caused the one with the bad turbo to loose RPM from there.

    Boost gauges would tell in a second what the problem if it’s boost related. Vacuum gauges would tell if its a fuel filter problem.

    I am 100% against just dismantling a engine to “try” stuff. Information is key, but I do not think you are one for just taking apart an engine either, based on your experiences and thoughtful posting over the years.


    "I
    would apply throttle and the engines would both go to around 1700-1800 RPM. Then only one would advance. Increasing throttle caused the one with the bad turbo to loose RPM from there."

    When I see a completely 'frozen' turbo on a Cummins 6b the offending engine often loses some rpm after a throttle up as the governor settles back to its max speed without boost.
    That is typically a few hundred rpm at most and is always associated with black smoke.
    On a 6b with typical props that would likely occur somewhere near that 1700 rpm area as boost starts to build o the 6B there with twins (rated at 3,000rpm).

    The differences I see here so far are:
    - no black smoke
    - the rpm drops are in stages
    - rpm drops all the way to zero
    - this engine is likely rated at 2400-2600 rpm

    At any rate it is east to look for black smoke as well as many techniques to look for fuel starvation issues.
    If the offending engine black smokes he may have a turbo and/or air problem.
    Of course if the other engine black smokes it is likely just overloaded and attempting to make up for the offending engine that is not producing power and is at a lower rpm.
    Northport NY

    Comment


      #32
      Originally posted by smitty477 View Post



      "I
      would apply throttle and the engines would both go to around 1700-1800 RPM. Then only one would advance. Increasing throttle caused the one with the bad turbo to loose RPM from there."

      When I see a completely 'frozen' turbo on a Cummins 6b the offending engine often loses some rpm after a throttle up as the governor settles back to its max speed without boost.
      That is typically a few hundred rpm at most and is always associated with black smoke.
      On a 6b with typical props that would likely occur somewhere near that 1700 rpm area as boost starts to build o the 6B there with twins (rated at 3,000rpm).

      The differences I see here so far are:
      - no black smoke
      - the rpm drops are in stages
      - rpm drops all the way to zero
      - this engine is likely rated at 2400-2600 rpm

      At any rate it is east to look for black smoke as well as many techniques to look for fuel starvation issues.
      If the offending engine black smokes he may have a turbo and/or air problem.
      Of course if the other engine black smokes it is likely just overloaded and attempting to make up for the offending engine that is not producing power and is at a lower rpm.
      You are correct, a turbo failure will overfuel and cause black smoke

      KEVIN SANDERS
      4788 LISAS WAY - SEWARD ALASKA
      where are we right now​​​​​​???​

      https://share.findmespot.com/shared/...j23OquWOj2N3Xe

      Comment


        #33
        Can not confirm or deny black smoke at this time

        I didn't check... I had family and friends on board.. was busy keeping an eye on everything else.

        But it's normal for a diesel to smoke when under load, right? So as I'm accelerating on to a plane some smoke is expected?
        ​​​​

        Comment


          #34
          Originally posted by infy View Post
          Can not confirm or deny black smoke at this time

          I didn't check... I had family and friends on board.. was busy keeping an eye on everything else.

          But it's normal for a diesel to smoke when under load, right? So as I'm accelerating on to a plane some smoke is expected?
          ​​​​
          "But it's normal for a diesel to smoke when under load, right?"
          Only under heavy loads..

          "So as I'm accelerating on to a plane some smoke is expected?"
          1-2 seconds of so followed by a quick clearing of smoke is usually OK.
          Black smoke that is always visible in the exhaust steam and/or on the horizon identifies an overload that will eventually lead to failures.
          If you have low rpm and black smoke you are in an over fueled and overloaded condition as a result of some type of problem which needs correction.

          If one engine is suffering from fuel starvation and the other is forced to try and make up the difference you will have an overload in that engine.
          So knowing if you have black smoke is another symptom, knowing which engine is pretty important as well.
          Northport NY

          Comment


            #35
            When I take it out for a test I may strap a GoPro on to the back and on to the instruments so I have references later.

            I don't want to beat it up too much knowing there's an issue. The first tests will be at dock. I'll warm it up and then rev it to 1500, 1700, and 2000 rpm or so in neutral. See how it responds.

            Fuel filters are coming in on Wed... Racor 2040N-02 and Baldwin PF7572. I'll hopefully have the engine back together on Saturday.

            Oil filters coming in on Wed too. Baldwin P7053 Full Flow and Baldwin P7185 By-Pass for port and starboard. After the oil change I may take it out and put it under load.

            Comment


              #36
              "When I take it out for a test I may strap a GoPro on to the back and on to the instruments so I have references later."
              A good idea but usually very hard to capture on camera.


              "
              The first tests will be at dock. I'll warm it up and then rev it to 1500, 1700, and 2000 rpm or so in neutral. See how it responds."
              Your high idle speed (no load) should be your rated rmp +8% or more - i do not know the rated rpm on that engine.
              Examples - if rated rpm is 3,000 high idle would be 3,240 or more, if rated rpm is 2,500 then high idle would be at least 2,700 or more.

              Under load you engines should see rated rpm at the very least - reaching rated rpm +3-5% at all times is a best practice to avoid overloading.

              Fuel filters are coming in on Wed... Racor 2040N-02 and Baldwin PF7572. I'll hopefully have the engine back together on Saturday.
              If you are going with 2 mic filters the vac gages become that much more valuable.
              .
              Northport NY

              Comment


                #37
                Busy weekend coming up! Hopefully these match up as replacements for the part numbers coming out.
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                  #38
                  Infy, hope you bought two more of every filter as spares you’ll keep tucked away for a rainy day. Or more like a rough day that stirs the crap up off the bottom of the tanks and plugs a filter unexpectedly! Good luck this weekend! Hope those filters resolve your issue!
                  Jim Gandee
                  1989 3888
                  Hino 175's
                  Fire Escape
                  [email protected]

                  Comment


                    #39
                    New filters are in. Super easy. Engine starts and runs. I haven't taken it to temp first. Was going to change the oil before that...

                    Need 14 galons or 52 liters of oil for the two..
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                    But I ran in to a problem... The west West Marine 12v oil pump I have won't fit down into the oil access tube. I'm not sure what fitting I need... Any ideas?

                    I may just cut it and put a new cap on...

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                      #40
                      I adapt mine with a couple of brass fittings to the hoses. It works best with the hose on the bottom of the boat. If the oil isn’t warm you can expect it to take a long time.
                      P/C Pete
                      Edmonds Yacht Club (Commodore 1993)
                      1988 3818 "GLAUBEN”
                      Hino EH700 175 Onan MDKD Genset
                      MMSI 367770440

                      Comment


                        #41
                        Agree with Pete to warm up engines to temp then change the oil.
                        Dave
                        Edmonds, WA
                        "THE FIX"
                        '93 2556 5.7 Bravo II 2.0:1 18 1/4x19 P
                        (.030 over-Vortec top end-part closed cooled)
                        The rebuild of my 2556 https://www.baylinerownersclub.org/f...76?view=thread
                        Misc. projects thread
                        https://www.baylinerownersclub.org/f...56-gctid789773

                        Comment


                        • Pcpete
                          Pcpete commented
                          Editing a comment
                          Operating temperature warmed up.

                        • builderdude
                          builderdude commented
                          Editing a comment
                          👍🏼

                        #42
                        Yeah I only discovered that the oil pump won't work after warming up first. I'll try and see if I can find a fitting.

                        Both port and starboard Racor replaced. Starboard has same secondary fuel filter as the part didn't come in on time. Port has a new secondary.

                        Ok I'm a little stumped here. I got both engines more or less to safe temp.. idle for about an HR.. but the RPM I'm reaching in neutral are less than what I am able to reach under load?

                        Revved port first.. reached max about 1.9k rpm. (This is the one that stalled twice under load and started this thread.)
                        https://youtu.be/9ADnBzZXoWU
                        ​​​​​
                        Revved starboard side... Reached max 1.5k rpm. It reached 1,800 under load last time I was out.
                        https://youtu.be/W9USyhrToYM

                        ​​​
                        I've read elsewhere these engines are rated for 400 horsepower at 2300 RPM. I should be able to reach at least 2,300.

                        Reversed port/starboard fuel tanks. Same results.

                        Opened both tank fuel caps. Same results
                        ​​​​​​
                        can't check for smoke unfortunately... It's night..

                        i could use some ideas

                        ​​​​​Bad fuel? Injectors? On a gas engine I can shut off a cylinder by pulling a plug lead.. not sure if there's an easy way to do that on a diesel.
                        ​​​​​​

                        Comment


                          #43
                          Infy, I think your tachs are not working properly. In both vids you can here the engines reving higher after the tachs stop their movement. Watch it close and you see what I’m talking about. I’d suggest you put a laser tach on both of those engines to get an accurate RPM.
                          Jim Gandee
                          1989 3888
                          Hino 175's
                          Fire Escape
                          [email protected]

                          Comment


                            #44
                            Interesting idea.. it's possible that when I was under way tachs were shaken a bit more loose. that would explain why they may have been reading different values.

                            I'll pick up a tach at west Marine and try replacing them. But to be honest on the starboard side I could not feel any difference between 75% throttle and 100%.

                            Comment


                              #45
                              First go to amazon and get a digital non contact laser tach. You stick a reflective patch to the flywheel accessed by pulling the rubber plug at the top of the bellhousing. It a matter of point the laser on to the flywheel and the laser will catch the reflections of the dots. If you choose to replace your current tachs, I’d be interested. There are adjustments on the back housing that may have been set for a larger or smaller gear ratio for the sending unit.
                              P/C Pete
                              Edmonds Yacht Club (Commodore 1993)
                              1988 3818 "GLAUBEN”
                              Hino EH700 175 Onan MDKD Genset
                              MMSI 367770440

                              Comment

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