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  • Black Tank Leaking, need diagrams

    My black has a serious leak near the top of the tank (not where the toilet line of vent pipe enters). I cannot see the location of the leak but it only leaks when the tank is full....pours out of the underbelly.

    I'm out of warranty and may attempt a repair myself. I need a diagram of how/where my holding tanks are located in the frame and locations of all fittings. Can a moderator ask Grand Design to send that to me?
    2019 Solitude 384GK-R.

  • #2
    Originally posted by KirbyRVA View Post
    My black has a serious leak near the top of the tank (not where the toilet line of vent pipe enters). I cannot see the location of the leak but it only leaks when the tank is full....pours out of the underbelly.

    I'm out of warranty and may attempt a repair myself. I need a diagram of how/where my holding tanks are located in the frame and locations of all fittings. Can a moderator ask Grand Design to send that to me?
    GDRV-Megan -- Kirby's VIN is in his profile. Please send him a HOLDING TANK LAYOUT diagram and a DWV PLAN diagram.

    Based on the copies I have (which *may* match your trailer) the black tank is literally right under the bathroom, street side. The output connections appear to run out the end facing the shower (back end of the trailer, if that makes sense). The "Full Way Termination Valve" is right outside of the tank exit (activated by the handle).

    Based on your description of the problem I'd focus on the vent line connection. I'm usually wrong when it comes to plumbing, so let's hope Cate&Rob chimes in here soon.
    Forum moderators are not GD employees--we are volunteers and owners presumably just like yourself. Unless specifically mentioned otherwise, we have nothing to gain should you choose to purchase a product or engage a service we discuss on this forum.

    2017 Ford F-350 DRW, '19 315RLTSPlus

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    • #3
      Originally posted by KirbyRVA View Post
      My black has a serious leak near the top of the tank (not where the toilet line of vent pipe enters). I cannot see the location of the leak but it only leaks when the tank is full....pours out of the underbelly.

      I'm out of warranty and may attempt a repair myself. I need a diagram of how/where my holding tanks are located in the frame and locations of all fittings. Can a moderator ask Grand Design to send that to me?
      Hi KirbyRVA,

      I am not sure how to interpret your statement (not where the toilet line of vent pipe enters) ??

      The most likely leak points at the top of the tank are the rubber grommets where the pipe from the toilet or the vent line pipe enter the tank. This will be into the top surface of the tank, behind the aft wall of the pass thru storage area, directly below the toilet. The attached pictures (for reference) are of the vent/fill line into a bathroom grey tank. (I had to remove this drain line to shorten the insertion length, on my Reflection)

      If these grommets in your black tank are NOT the source of the leak, you may have a split in the tank itself. This will require dropping the coroplast and removing the tank to solve.

      Rob
      Attached Files
      Cate & Rob
      (with Border Collies Molly & Angel + Kitties Hazel & Elsie)
      2015 Reflection 303RLS
      2022 F350 Diesel CC SB SRW Lariat
      Bayham, Ontario, Canada

      Comment


      • #4
        I can access and clearly see the top of the tank where both the 3" pipe from the toilet and the 1 1/2" vent pipe enter the tank through the grommets. When I filled the tank, there was only a small leak around the vent pipe grommet.....just a little puddle next to the vent pipe. The amount of water gushing out of a small hole I punched through the coroplast did not come from around the vent. I cut the coroplast in the shape of bomb bay doors near the tanks and got a nasty shower. I removed many pounds of soggy insulation. I cannot see enough of the tank to tell if it has a split near the top. I now suspect the back flush connection as a possible leak point since I assume it is mounted through a side near the tank top. I have spayed the area with bleach and will allow it to fully dry before investigating further.

        My tanks appear to be one gray tank primarily for the clothes washer (which we do not have) on the curb side, the black tank in the middle, and a second gray water tank on the road side. Having the diagram/s that shows me where the backflush enters the tank will help me find that.

        I do have the dealer tech scheduled to come on Thursday in case the tank needs to be replaced or the repair is beyond my ability and/or patience.
        2019 Solitude 384GK-R.

        Comment


        • #5
          KirbyRVA
          The black tank flush is "spin welded" into the forward end of the tank, about an inch down from the top.
          (Thanks to Country Campers Brian for this picture of the inside of a new tank, taken at our last tech seminar at Grand Design)
          This is another possible location for the leak that you describe. Dropping the front edge of the coroplast should allow you to see this location.

          Rob
          Attached Files
          Cate & Rob
          (with Border Collies Molly & Angel + Kitties Hazel & Elsie)
          2015 Reflection 303RLS
          2022 F350 Diesel CC SB SRW Lariat
          Bayham, Ontario, Canada

          Comment


          • #6
            https://gdrvowners.com/member/178-kirbyrva
            Please, please check for other sources of water other than the black water tank, if you haven't already. We had a similar experience last June and although the water seemed to be in the area of the tanks the actual leak was a threaded fitting on the backside of the nautilus control panel and was only apparent when the water pump was used to pressurize the system.
            John
            2018 Momentum 395M
            2018 Ram 3500 Dually
            Every day is a Saturday, but with no lawn to mow.

            Comment


            • #7
              Originally posted by howson View Post

              GDRV-Megan -- Kirby's VIN is in his profile. Please send him a HOLDING TANK LAYOUT diagram and a DWV PLAN diagram.

              Based on the copies I have (which *may* match your trailer) the black tank is literally right under the bathroom, street side. The output connections appear to run out the end facing the shower (back end of the trailer, if that makes sense). The "Full Way Termination Valve" is right outside of the tank exit (activated by the handle).

              Based on your description of the problem I'd focus on the vent line connection. I'm usually wrong when it comes to plumbing, so let's hope Cate&Rob chimes in here soon.
              Sent to KirbyRVA - Thanks!

              Comment


              • #8
                Originally posted by JBill9694 View Post
                https://gdrvowners.com/member/178-kirbyrva
                Please, please check for other sources of water other than the black water tank, if you haven't already. We had a similar experience last June and although the water seemed to be in the area of the tanks the actual leak was a threaded fitting on the backside of the nautilus control panel and was only apparent when the water pump was used to pressurize the system.
                This was clearly a black water leak.
                2019 Solitude 384GK-R.

                Comment


                • #9
                  Originally posted by GDRV-Megan View Post

                  Sent to KirbyRVA - Thanks!
                  I don't see any attachment on my end.

                  Sorry. Found it as a message in my profile.
                  Last edited by KirbyRVA; 04-08-2020, 12:36 PM.
                  2019 Solitude 384GK-R.

                  Comment


                  • #10
                    Update: I dropped more of the coroplast and exposed most of the black water tank. My BW tank is mounted North-South with the dump opening and valve on the south end of the tank. In what I would call another case of bad engineering, the flush nozzle is also mounted on the south end above the tank outlet. In every other RV I've owned, the flush nozzle is mounted on the end of the tank opposite the outlet which allows the flushing water to sweep solids toward the outlet. How GD mounted this flush nozzle explains why the back flush works so poorly compared to other RV's I've owned.

                    All of the clamps and fittings at the outlet and at the flush nozzle are tight and there is no evident of a leak in that area. Since the leak only occurred when the tank was completely full, I looked again carefully at the grommets where the toilet pipe and vent pipe connect at the top of the tank. As noted previously, I can see only a small stain around the vent pipe where I noticed a tiny bit of water during the test.

                    I did notice evidence of liguid staining at the southwest corner of the tank under the rig. It was dry today but it looks like dirty water has previously run down the tank side at that location. I can only feel part of the tank at that location and I could not feel any split, holes or damage in that area. The tanks were obviously installed in the frame before anything else was built so I have no idea how you can remove that tank. It seems to have a lip that sits on framing welded for the full length of the tank. Perhaps the tank is slid forward (toward front of coach) and it can be dropped out.

                    I'm stumped. Will let dealer tech deal with it. Since we plan to keep this rig on our site full time until we get too old to use it, I am considering disconnecting the 3" line near the top of the tank, capping the tank and running 3" PVC directly to our sewer connection.
                    2019 Solitude 384GK-R.

                    Comment


                    • #11
                      KirbyRVA
                      Thanks for the detailed update.
                      I have never seen a flush connection at the same end as the gate valve drain . . . as you say, this makes no sense.

                      The tank will be T shaped and is sitting on two rails as you describe. One or the other (or both) of these rails should be bolted (not welded) into place so that the tank can be removed from below. These T shaped tanks have a formed bottom with a flat plate bonded across the top. The seal between these two pieces might be the source of the leak.

                      On a full time site, eliminating the tanks and connecting the various drains directly to the sewer has considerable benefits.

                      Edit: Added a picture of someone else's (grey) tank replacement project as a reference . . . I don't have a source for the original photo.

                      Rob
                      Attached Files
                      Last edited by Cate&Rob; 04-08-2020, 04:50 PM.
                      Cate & Rob
                      (with Border Collies Molly & Angel + Kitties Hazel & Elsie)
                      2015 Reflection 303RLS
                      2022 F350 Diesel CC SB SRW Lariat
                      Bayham, Ontario, Canada

                      Comment


                      • #12
                        Originally posted by Cate&Rob View Post
                        KirbyRVA
                        Thanks for the detailed update.
                        I have never seen a flush connection at the same end as the gate valve drain . . . as you say, this makes no sense.

                        The tank will be T shaped and is sitting on two rails as you describe. One or the other (or both) of these rails should be bolted (not welded) into place so the the tank can be removed from below. These T shaped tanks have a formed bottom with a flat plate bonded across the top. The seal between these two pieces might be the source of the leak.

                        On a full time site, eliminating the tanks and connecting the various drains directly to the sewer has considerable benefits.

                        Edit: Added a picture of someone else's (grey) tank replacement project as a reference . . . I don't have a source for the original photo.

                        Rob
                        I expected to see bolts on at least one of those rails. I did not. Both looked welded to me. If so, that is not surprising in view of the other design goofs I've seen on this thing.
                        2019 Solitude 384GK-R.

                        Comment


                        • #13
                          UPDATE: Dealer tech came today and had me fill the tank. He confirmed that the tank was leaking from an apparent split near the top at the corner where I had seen some evidence of dirty water stains. He said tank replacement was necessary and will be done after they get approval from the extended service plan. He noted the placement of the flush nozzle at the wrong end of the tank and said he hoped they had been made aware of this and a replacement tank might have that installed at the other end. He acknowledged that he and the other techs see things often with RV's that suggest common sense does not always prevail when these things are made.

                          Also, the outboard angle iron holding the tank and a cross support are screwed into the frame allowing tank removal.
                          2019 Solitude 384GK-R.

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