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    38xxvent bubbling during fill up

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Name:	858A7B5C-28E2-46AB-8B88-06AB4B12AE82.jpeg
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ID:	436687 I have had my 1987 3818 for almost two years and have had to fill up the diesel tanks very slowly as it bubbles and gurggles on file up.

    i pulled the vent hoses today and have found that when I remove the fill cap and then blow into the vent it bubbles into the tank. So that indicates to me that either the Vent tube has dropped (does not seem possible as it is welded), the vent hose is hooked up the the wrong connection on the tank (is hooked up to #5 in the picture). Or is a design flaw.

    any suggestions how I can get the vent to ....vent??

    thanks!
    Craig
    Nanaimo bc
    1987 bayliner 3818
    w/ 175 Hinos no Genny, but solar to run everything!
    10ft Livingston with centre console and 15hp on davits / winch

    #2
    Check if the vent line bellies below the tank...you may have gotten some fuel in the low spot and it's"stuck" there. That would make it gurgle...lift it above the tank so that it drains...or remove it and empty it.

    1988 3888
    Twin Cummins 6BT's 210hp
    Onan 8.0
    Boating Raritan Bay

    Comment


      #3
      Thanks Nick. Yes tried it. Can hear the bubbling in the tank.
      Craig
      Nanaimo bc
      1987 bayliner 3818
      w/ 175 Hinos no Genny, but solar to run everything!
      10ft Livingston with centre console and 15hp on davits / winch

      Comment


        #4
        My 3270 does the same thing for the same reason. The vent is lower than the fill and the loop goes below the top of the tank. A friend of mine had his vent hoses rerouted to loop above the tank. problem solved. It is on my never ending "to do" list.

        Greg
        Newport, Oregon
        South Beach Marina
        1986 3270 with twin 110 HP Hino diesels. Name of boat "Mr. Darcy"
        Past work history: Prototyping, tooling, and repair for Reinell,. General fiberglass boat repair starting in 1976.
        Also worked as heavy equipment mechanic, and machinery mechanic for over 30 years.

        Comment


          #5
          Mine are looped on our 3818
          P/C Pete
          Edmonds Yacht Club (Commodore 1993)
          1988 3818 "GLAUBEN”
          Hino EH700 175 Onan MDKD Genset
          1980 Encounter Sunbridge "Misty Blue" (Sold)
          MMSI 367770440
          1972 Chevrolet Nova Frame off Resto-mod in the garage
          Boating on the Salish Sea since 1948

          Comment


            #6
            Bubbles in the tank doesn't sound right...can you fill them up full? If the vent tube was low, that should be the max that it can be filled....
            . . .It places the lotion in the Basket. . .and that basket happens to be in a 1987 Bayliner 3870 w/ Hino 175's

            Comment


              #7
              I’m going to have to ck my tank vent lines as to fill the last 25 gals or so of each tank is very slow with lots of burps of bubbles and fuel out the fill ports. You guys have me thinking, thank you.
              Jim Gandee
              1989 3888
              Hino 175's
              Fire Escape
              Fyrflyer@ca.rr.com

              Comment


                #8
                I have not completely filled them up. Took too long.

                i think the venting is only happening through the fill hose.

                my vent lines are looped at the top by the thru Hull. When I removed the vent hose and blew into it it had a straight line to the tank so nothing in the hose.

                might pull the return line from the engine and see if it perhaps is ahooled up to the vent line?
                Craig
                Nanaimo bc
                1987 bayliner 3818
                w/ 175 Hinos no Genny, but solar to run everything!
                10ft Livingston with centre console and 15hp on davits / winch

                Comment


                  #9
                  Maybe this should be treated as a couple of different "problems"...if you tie all the symptoms together, it might confuse the issue.

                  1. If you can blow into the vent and make bubbles in the tank, then the tank is full or filled up to the level of the vent tube - this is normal and can be ignored unless you suspect the vent tube extends too low into the tank to give you a full tank (not likely). But you cannot blow into the fuel, make bubbles and not have had a spill the last time you filled up. Basically, the vent cannot be lower than the fuel. Also, blowing into the vent line is not likely to carry the same volume as the fuel going in when filling. Fuel filling may be overpowering the vent line.

                  2. It is possible that the gurgling you hear when filling may be caused by the fuel "sudsing up". You can see this if you fast pour fuel into a 5 gal container, for example - lots of bubbles. The sound you hear may just be the fuel bubbles. This could be normal.

                  3. The vent line may be turning into a "one-way" valve, meaning, it's possible that you may have a collapse in the vent line allowing you blow in, but not allow as much out as might be required.

                  4. You may have the nozzle in too far when filling...? This would cause the fuel to try to back up the fill line and would make bubbles/gurgling/suds. Back the nozzle out a bit and see if it helps.

                  When you last filled up, did you have any spill out the vent...? If so, then you might still have some residual fuel left in the vent line. ( call me stubborn for not paying attention to the fact that you already did this )

                  Do you get the gurgling at the end or during the whole filling cycle right from the beginning. If you get it from the beginning, you might have a wee amount of fuel in the vent line or the vent line may be blocked slightly. If you only get it at the end, the bubbles caused during fill have not settled yet...stop filling for a couple of minutes and resume and see if it changes the symptoms. If so, the bubbles are the culprit and might be an indication that the pump passes too much fuel flow.

                  Can you try using a smaller filling nozzle...? Maybe your fuel station doesn't have a small nozzle. A smaller nozzle would produce less "suds" in the tank and would allow for air escape back out the fill. This in itself would create bubbling or gurgling effect.

                  Was there any fuel in the vent line at all when you disconnected it to check for fuel...? If so, and there was any in there, you may still have some residual from the inner lining collecting in the loop.

                  Do both tanks do the same thing...? If so, try changing the fueling station...it is likely the fuel is pumped too fast and the vent can't handle it. In this case, the gurgling noise is actually the fuel trying to back up into the fill line and is only manifested in the vent line (the only other insufficient escape).

                  How long does it take to fill how many gallons...just to get an idea of the flow rate...
                  1988 3888
                  Twin Cummins 6BT's 210hp
                  Onan 8.0
                  Boating Raritan Bay

                  Comment


                    #10
                    Originally posted by Jim_Gandee View Post
                    I’m going to have to ck my tank vent lines as to fill the last 25 gals or so of each tank is very slow with lots of burps of bubbles and fuel out the fill ports. You guys have me thinking, thank you.
                    Jim...may be an indication that the pump is pushing too fast through a big nozzle. Try stopping when you get to the end, wait a couple of minutes then resume. Did it go away = bubbles.
                    1988 3888
                    Twin Cummins 6BT's 210hp
                    Onan 8.0
                    Boating Raritan Bay

                    Comment


                      #11
                      My gut feeling is that the vent line may be connected to a pickup fuel fitting at the tank rather than a vent fitting. The only way to find out is to unscrew the fitting and look.
                      If this is the case it is also possible that the return line is attached to a vent fitting instead of a pickup tube.
                      "Adios Dinero"
                      1997 3988 with new 330 Cummins
                      Photo Credit: Whiskywizard

                      Comment


                        #12
                        Jim...may be an indication that the pump is pushing too fast through a big nozzle. Try stopping when you get to the end, wait a couple of minutes then resume. Did it go away = bubbles.

                        Nick, Good thought but I’ve tried filling the last of the fuel so slow the fuel dock personnel start to wonder if I croaked, it takes so long!
                        Jim Gandee
                        1989 3888
                        Hino 175's
                        Fire Escape
                        Fyrflyer@ca.rr.com

                        Comment


                          #13
                          As "Adios Dinero" commented, the lines may be on the wrong fittings.

                          When fuel blows back out of the fill, it's because the air in the tank has gotten compressed by the incoming fuel and has no where else to go. This is the purpose of the vent (that, and allowing air into the tank as the engine takes fuel out).

                          Put your ear on the tank and have someone else blow into the vent. If you hear bubbling coming from within the tank, the incoming air is being discharged below the level of the fuel. This is wrong; the vent shouldn't have a tube, it's just a hole in the top of the tank with a hose atached. If there's a tube on it, you lose the ability to vent the tank (during fill-up) as soon as the rising level of fuel covers the end of the tube.

                          Return lines sometimes have a tube, sometimes not. If yours does, and the hoses are switched between return and vent, the return will still work just fine but the vent will not. If the vent line is switched with a pickup line, whatever that pickup was supposed to supply won't work.

                          There are many reasons why vent lines don't work -- fuel in a belly, corroded/blocked vent fittings for example. It's a good idea to check those things, too. (The vent hose should run continuously uphill to well above the thru-hull vent then go back down to the vent.) Your situation (bubblling in the tank), sounds different; that's not the sound fuel in a hose belly makes.

                          Good luck.
                          100T MMC 2307794

                          Comment


                            #14
                            Thank you all. Will check the different fittings and see what is what.

                            Tank is half full now. Fuel dock has large fill up nozzle but I end up having to go sooooo slow. Yes other customers stare at me as I hold up the process!

                            yes spilled fuel last time when I tried to go too fast. Even when I go slow I still get drips out of the vent tube.
                            Craig
                            Nanaimo bc
                            1987 bayliner 3818
                            w/ 175 Hinos no Genny, but solar to run everything!
                            10ft Livingston with centre console and 15hp on davits / winch

                            Comment

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