Water Pump Won't Pump with 1/3 Full Tank

[lmlayfield]

Thank you Boomer! Your original thread is what caused me to dig deeper into this issue. You made me realize my problem was not a one-off and likely a design issue.

I certainly hope this thread does spread to other owners so they become aware of both the problem and the potential health and safety hazards of large shoulder mounted tanks. I must admit I am dismayed at the absolute denial from Grand Design to recognize and address this issue. To date they are still denying this is a design issue. I have every belief they are relying on the one year warranty to try and foreclose owner issues and avoid what I think could be a class action lawsuit and recall. Yes, I am an attorney.

Hopefully the Moderators will recognize the important potential health and safety issues that arise from the lack of awareness of this issue, and place this thread prominently in the emails sent to forum members.

[Second Chance]

Thank you Boomer! Your original thread is what caused me to dig deeper into this issue. You made me realize my problem was not a one-off and likely a design issue.

I certainly hope this thread does spread to other owners so they become aware of both the problem and the potential health and safety hazards of large shoulder mounted tanks. I must admit I am dismayed at the absolute denial from Grand Design to recognize and address this issue. To date they are still denying this is a design issue. I have every belief they are relying on the one year warranty to try and foreclose owner issues and avoid what I think could be a class action lawsuit and recall. Yes, I am an attorney.

Hopefully the Moderators will recognize the important potential health and safety issues that arise from the lack of awareness of this issue, and place this thread prominently in the emails sent to forum members.

@lmlayfield -

Here are a few forum tips:

1) If you use "Reply With Quote" (to the right of "Reply") as I have here, folks will know to whom you are responding and that person will get a notification.

2) You can also tag folks using the "@" symbol and their user name (as I have done yours) - they'll also get a notification that way.

Rob

[dryfly]

The third dealer agreed with my diagnosis of the problem and used plywood and 2x4s to support the tank bottoms using the same flimsy metal straps. I have rejected this repair as insufficient. I agree it will work for a short time, but the straps will stretch again and the untreated wood will get soft and rot and the problem returns.

What are the straps made of that allow them to stretch? Wouldn't the underbelly being protected from the weather prevent the wood from getting soft and rotting?

[Tom Traveler]

The problem arises because my tanks are supported by the shoulders only. There is no rigid support underneath the tanks. There are three flimsy metal straps that do not even touch the bottom the tanks when they are empty. These straps are screwed to the cross frame members and under stress they can stretch and the screw holes elongate. The tanks are 60” wide (left to right in the frame) 42” long (front to back) and the depth varies from about 4” on the passenger side to about 7” on the driver side. The tank bottom slopes towards the tank outlets on the deeper driver side. The third dealer agreed with my diagnosis of the problem and used plywood and 2x4s to support the tank bottoms using the same flimsy metal straps.

It's seems clear that the solution to this issue is internal top-to-bottom baffles in the tanks (best solution as it would also reduce sloshing but probably not likely because of cost and it doesn't help existing RVs) or some kind of support under the belly of the tanks. Would it be possible to get some wider view pictures of the tanks showing how they are supported at the shoulders and of the layout of the underbelly in general? I'm curious regarding the whole layout of the underbelly because I've never seen it. What is between the bottom of the tank and the coroplast? I assume there is some insulation.

You stated that one dealer added 2x4s and plywood. Assuming no constant leaks in the tanks, exterior plywood and treated 2x4s should last longer than the RV. Could the 2x4s be supported by the bottom T of the front-to-back main I-beams? I agree that supporting these with the thin straps is probably not useful. Is there enough room below the tank, but above the coroplast, for that kind of structure?

I've done a search but haven't been able to find good pictures. Can anybody refer me to other posts with good pictures of the underbelly? Will GD provide them?

[lmlayfield]

It's seems clear that the solution to this issue is internal top-to-bottom baffles in the tanks (best solution as it would also reduce sloshing but probably not likely because of cost and it doesn't help existing RVs) or some kind of support under the belly of the tanks. Would it be possible to get some wider view pictures of the tanks showing how they are supported at the shoulders and of the layout of the underbelly in general? I'm curious regarding the whole layout of the underbelly because I've never seen it. What is between the bottom of the tank and the coroplast? I assume there is some insulation.

You stated that one dealer added 2x4s and plywood. Assuming no constant leaks in the tanks, exterior plywood and treated 2x4s should last longer than the RV. Could the 2x4s be supported by the bottom T of the front-to-back main I-beams? I agree that supporting these with the thin straps is probably not useful. Is there enough room below the tank, but above the coroplast, for that kind of structure?

I've done a search but haven't been able to find good pictures. Can anybody refer me to other posts with good pictures of the underbelly? Will GD provide them?

@Tom Traveler -

Baffles can certainly help with some issues, but here I think you are more accurate with rigid support underneath the tank. In my case the wood was untreated plywood and untreated 2x4s. They painted it black to provide some coating. But, I live in Alabama where the humidity and moisture are pervasive, not to mention I now have a cut and taped coroplast which never seals as tight as one piece does. The kicker was they reused the thin metal straps which have no real ability to support the weight of nearly 50 gallons of water. To make matters worse they blocked up one end of the shoulder mounted tank to try and make the bottom level. So now with a full load of water which will stress the thin metal bands, the tank will bear weight only on each end of the shoulders instead of down the entire length. GD has since agreed verbally to pay the dealer to redo the repair using two rigid metal bars to support the tank bottom while the shoulders are level on the cross members. I am cautiously optimistic this will work, but the same dealer who thought wood, blocking and straps was a good idea.

As originally built there is no insulation or anything else between the bottom the tanks and the coroplast. Momentum TTs do have heated ducts into the area between the floor and the coroplast to prevent freezing. There are no tank heaters.

The challenge in adding rigid supports parallel to the frame using the perpendicular cross supports is the bottom of the tank is not level. On the passenger side the tank is only about 4” high and the bottom is several inches above the level of the frame bottom. On the drivers side the tank is about 7” high and lower than the bottom of the frame level. So adding the rigid support requires accurate measuring and placement of the supports in order to alleviate the problem. Hope the pictures below give you a better perspective. If someone can tell me how to rotate the pictures I will do so.

[Tom Traveler]

Thank you, Tripp, for the info and pictures. I can rotate the pictures when I expand them. This will be helpful to understand the whole thing. I have a Solitude with one 90 gallon tank and have never checked to see if I have an issue as I haven’t used the fresh water tank very much. One time I put in 15 gals to use the spray hose and between the spray hose and dumping the rest, I’m thinking there is still 5 - 10 gals in there. I am assuming the low end of the tank is on the left (driver’s) side underneath the Nautilus panel. I might try raising the right side of the RV with the Level-up jacks to see if I can drain more out of the tank.

Primarily, I have an (perhaps unhealthly) obsession with understanding how the things I use work, even if I don’t need to. That obsession hasn’t yet been strong enough to cause me to drop the coroplast when I don’t really need to, but stay tuned.

[lmlayfield]

Thank you, Tripp, for the info and pictures. I can rotate the pictures when I expand them. This will be helpful to understand the whole thing. I have a Solitude with one 90 gallon tank and have never checked to see if I have an issue as I haven’t used the fresh water tank very much. One time I put in 15 gals to use the spray hose and between the spray hose and dumping the rest, I’m thinking there is still 5 - 10 gals in there. I am assuming the low end of the tank is on the left (driver’s) side underneath the Nautilus panel. I might try raising the right side of the RV with the Level-up jacks to see if I can drain more out of the tank.

Primarily, I have an (perhaps unhealthly) obsession with understanding how the things I use work, even if I don’t need to. That obsession hasn’t yet been strong enough to cause me to drop the coroplast when I don’t really need to, but stay tuned.

Don’t forget to account for the hot water heater (assuming you don’t have tankless) when you do your calculations. I bypassed my HW on all my testing to make sure I was accurate.

[LanerC]

If, like us, you don't get too hung up on achieving perfect level when setting up camp, it may simply be that your unit is slightly off one way or another. The water tanks in most RVs are wide and shallow. When you are getting down to the bottom of your supply, it may be that the water is in a different side or end of the tank ... down where those marginally accurate sensors are. I've occasionally had to raise or lower the front jacks to resume pumping.

Iv had to do this often when pulled over on the side of the road.

[savagkd]

Just thinking out loud... Would it be possible to insert something like a flexible fuel pickup tube, commonly used in marine and aircraft fuel tanks? This would extend the pickup into the center low point of the tank, no matter how far it sags. I haven't tried it myself, just a thought.