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    38 - Black accumulating on aft quarters...?

    My 6BTA's 210hp WOT (I believe) is 2800...I cruise at 2350...No problems whatsoever - engines have about 140 hours - repowered in 2012. Temp running at 180-185 all day. Oil pressure stays at about 55psi.

    Some light black is accumulating on each of the aft quarter corners equally. Normal...? Or should I be looking...

    Speed at that RPM is typically 16.5 to 17.5 depending on sea state...trim tabs at about 75% down (guesstimate). Hopefully I'll get a chance at WOT tonight. Thinking I might take an inch off the prop diameter...they're only about an inch from tunnel walls and it looks like water turbulence is starting to chew at the prop's trailing edge of the tunnels.

    Thanks in advance...Nick
    1988 3888
    Twin Cummins 6BT's 210hp
    Onan 8KW

    #2
    To my knowledge and observations, the only way to stop the exhaust residue is a very log exhaust pipe extension. A light coating after a trip is no big deal. However, if it is heavy it can be an indicator of poor fuel burn or oil burning. I treat it as another sign to how my engines are running.
    P/C Pete
    Edmonds Yacht Club (Commodore 1993)
    1988 3818 "GLAUBEN”
    Hino EH700 175 Onan MDKD Genset
    MMSI 367770440

    Comment


      #3
      Thanks, Pete...it's more of an accumulation than a black on each run. No fuel/oil slick on startup or idling...no visible smoke while running...throttles very responsive.

      The only time it's a bit sluggish is after a fuel fill...then I can feel her squatting while accelerating and a bit slow on getting the bow down...

      1988 3888
      Twin Cummins 6BT's 210hp
      Onan 8KW

      Comment


        #4
        Could be a sign that the engine isn't getting enough air. Make sure your air filters are clean. Not sure if the 6BT 210's have aftercoolers, but if so, might be a sign they are starting to foul as well.
        Terry

        Comment


          #5
          Terry...good point on the filters (no aftercoolers). I'm thinking while the engines have low hours, I bet the filters have multiple seasons. Just picked up the boat early June so still going through the systems. Will definitely put the filters on the top of the list.

          Thanks again...
          1988 3888
          Twin Cummins 6BT's 210hp
          Onan 8KW

          Comment


            #6
            Nick, K&N’s. Easy to clean and recharge. I have them on all my vehicles and vessels.
            P/C Pete
            Edmonds Yacht Club (Commodore 1993)
            1988 3818 "GLAUBEN”
            Hino EH700 175 Onan MDKD Genset
            MMSI 367770440

            Comment


              #7
              I second Pete on the K&N's, use them on my Porsche and my Suzuki and will be putting on the boat when I get the chance. We too just bought our boat in November.
              P/C Bob Hicks JN
              Dock Holiday, 1992 Bayliner 3888 Double Cabin Flybridge Cruiser
              Twin Hino W04TI 210 HP Diesels with Hurth HSW630A 2.0:1 Trannys
              Westerbeke 8.0 BTD-614 8KW Genset
              Avon 9 ft 6 in Tender with a Tohatsu M8B 8HP outboard
              Currently moored at Stones in Nanamio, B.C.

              Comment


                #8
                Pete/Bob...Re: K&N's...are they different for marine vs automotive...? Don't marine filters handle the humidity better and require different care...?
                1988 3888
                Twin Cummins 6BT's 210hp
                Onan 8KW

                Comment


                  #9
                  Here is a good article via the BoatDiesel forum. If you're not a member there, it's worth dropping the $20. https://www.sbmar.com/articles/under...oubleshooting/
                  Terry

                  Comment


                    #10
                    I always read the instructions for use but I have used K&N's for over 20 years and trust the products. Haven't got the filters for the boat yet as only flying out to it tonight.
                    P/C Bob Hicks JN
                    Dock Holiday, 1992 Bayliner 3888 Double Cabin Flybridge Cruiser
                    Twin Hino W04TI 210 HP Diesels with Hurth HSW630A 2.0:1 Trannys
                    Westerbeke 8.0 BTD-614 8KW Genset
                    Avon 9 ft 6 in Tender with a Tohatsu M8B 8HP outboard
                    Currently moored at Stones in Nanamio, B.C.

                    Comment


                      #11
                      Originally posted by TenMile View Post
                      Here is a good article via the BoatDiesel forum. If you're not a member there, it's worth dropping the $20. https://www.sbmar.com/articles/under...oubleshooting/
                      TenMile

                      Terry...sorry I didn't respond to your recommendation...Thank you for that...

                      I read the article carefully and can't imagine it being more simple. I have been around engines for a long time and it made perfect sense to me (but not enough around marine engines or my 38 specifically). The logical paths presented would make it easy for anyone to do enough troubleshooting to find the source of a problem.

                      Thanks again and especially for the recommendation to join BoatDiesel forum...Nick



                      1988 3888
                      Twin Cummins 6BT's 210hp
                      Onan 8KW

                      Comment


                        #12
                        That article should be a sticky at the top of the cruisers forum. Great advice for any diesel engine owner. Good luck with the new rig.
                        Terry

                        Comment


                        • Nickp
                          Nickp commented
                          Editing a comment
                          Agreed...great article...thanks, again...

                        #13
                        Does a new K & N go on dry or does it get charged? I'm new to K&N's also. I too have same issue as Nick except I am still with the 175s and one side (port) is particularly dirtier than the other.
                        1988 38'
                        Shear Bliss

                        Comment


                          #14
                          I suffered this on my 3788 and did a ton of work as per posts.
                          I was even told a turbo rebuild would be the way to go
                          A sesoned Bayliner owner said test for WOT with a loaded boat and rpm is low repitch the prop a degree or 2.
                          Im convinced that boat was running from day 1 with incorrect pitch as even the bayliner fuss was getting black.
                          it was a new boat
                          came out of the hole and max speed was 23 not 17 not a spot of black on the transom.
                          Just my input
                          2001 Bayliner 3988 330 hp Cummins 6bta m3
                          950
                          Located in Blaine Harbour Marina

                          Comment


                            #15
                            My Hinos does it also, I believe that it is normal, diesels are dirty burn engines unless they have particulate filters on the exhaust to catch all the soot.
                            {Living our Dream}
                            John & Nancy
                            1988 Bayliner 38
                            175 Hinos 8.5 kw Westerbeke
                            Sandy Point Ferndale Washington

                            Comment

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