Is my fresh water belly pan compromised?

[GOUSC]

I recently winterized my Globetrotter and noticed my fresh water belly pan seemed a little low on the street side when I was walking behind where I park it. I did a search on Airforums and found the following threads on this topic;

Belly Pan Bulging - Airstream Forums (airforums.com)

Fallen fresh water tank - Airstream Forums (airforums.com)

The first thread makes it sound like it’s normal and nothing to worry about. The second thread makes it sound like there could be an issue. I’ve attached 5 pictures of my situation and wanted to throw it out to the Forum to get a consensus.

I recently attended a seminar at Alumalina and it was mentioned that sometimes the belly pan can come undone if you have rivets that fail. After the seminar I looked under my RV and didn’t notice anything unusual so I’m thinking this may have occurred on a recent trip to NY State. There were some rough roads but no rougher than any others we use travelled on. I started with a full tank, as I usually do. We only hook up to city water to refill our tank. I did not have to refill this tank on this trip and had about 6% left over a 2-week trip.

The street side of my tank is 8” off the ground. The curb side is 9 ¼ - 9 ½” off the ground.

Pic #1 – back view of my tank showing the street side is lower than the curb side.
Pic #2 – view from the curb side of the tank to the street side showing there is no sag on the street side.
Pic #3 – This shows there is a crease up in the back underside of the belly pan. I was wondering if maybe some road debris was kicked up causing this?
Pic #4 – This shows a screw has come loose in the access plate to the belly pan. This also shows there was no screw in the hole in the corner. It has either been missing since day 1 or has sheared off.
Pic #5 – Another pic of the access plate area.

I inspected all the bolts that go into to subfloor, or something, that hold up the fresh water tank pan. None of them are loose. It is my understanding from the above posts that this pan serves as the total support for the fresh water tank (i.e. there are no additional straps)

My questions;

1. Is this normal?
2. Any ideas of what caused the crease in the corner of the belly pan and does this cause any concern?
3. Regardless of the answers to #1 or #2, I think I would feel better if I could add some metal support straps, or something, that would give some additional support to this area. See post #7 of the 2nd link above. I’ve reached out to that person but this post is 5 years old so I don’t even know if they still access this forum or not.
4. If I put new screws into the belly pan to replace the one pulled loose in the access area and the one missing in the corner, do I need to worry about piercing the fresh water tank?

[Belegedhel]

Well, not knowing anything about your particular model, I would say that if it looks wrong, then something is probably wrong.

The first thing I would do is determine if each frame rail is essentially the same height (ie, one side of your suspension isn't riding lower than the other).

Next, I would have a look at WHY one side is hanging down... For example, if the tank supports have let loose, then maybe your tank is hanging down on one side and pushing the belly pan down (you might see evidence such as bulging skin, popped rivets, or missing screws), vs. being built in such a way as to accommodate a non-symmetrical tank (ie., is it lower on one end to allow it to completely drain).

You mention that you recently winterized the trailer--is the fresh water tank empty, or is it full of antifreeze? Have you done anything that might trap pressure in it and cause it to bulge?

At any rate, it sounds like you noticed that something is looking different. Our natural inclination is to say "it is probably just normal," and to look for someone who agrees with us, but you are only going to have real peace of mind if you can verify it for yourself. This may involve peeling back some of the belly skin to ensure the mounting of the FW tank is still in good shape.

good luck!

[GOUSC]

Belegedhel - One side of the suspension is not riding lower than the other.
The fresh water tank is empty / no antifreeze. there may be a small residual amount the drain plug is no all the way to the bottom of tank.

My understanding from the posts I referenced is that there are no tank supports other than the bolts I mentioned and these are secure. Since the tank pans are the only support, it's my understanding there is no peeling of belly skin that can be done as the tank is bolted to the floor. The only thing I can possibly inspect would be to remove the small access plate.

I really can't tell you if it was sagging before. I was just happened to notice it. When I looked closer I saw the dent underneath and the loose screw that I'm pretty sure were not there before.

To clarify, I'm not searching for someone to tell me it's probably normal unless this really is normal.

At this point, it looks to me like something cause a dent in the pan that made a screw pop loose. This may have done something to weaken the pan and cause it to bow in the middle. I'm not qualified to drop the full pan with all the pex connections that would need to be removed.

I'm hoping there is someone out there who has repaired this area before and can suggest ways to a) further support this area, if it is normal or, not normal b) put 2 new screws in to replace the stripped one and the missing one w/o penetrating the plastic tank. In addition, if anyone has a 2018 or newer 27 foot Globetrotter does the street side hang lower than the curb side by 1 1/2".

I will have to put ramps / blocks under the wheels to elevate this and get some more working room. I'm just asking what to look for ahead of doing this so I can be prepared to do whatever work I may be looking at if this is not normal.

[GOUSC]

see if these links work as the ones in the original post did not.



https://www.airforums.com/forums/f44...ng-117234.html

https://www.airforums.com/forums/f44...nk-153179.html

[richard5933]

Obviously not the same trailer model, but the tanks on my Excella hang lower on one end than the other. On purpose.

The waste tanks are lower to the ground on the end with the discharge ports.

The fresh water tank is lower to the ground on the end with the freshwater drain valve.

This is because of gravity and the need to have the tanks drain.

[dznf0g]

Originally Posted by richard5933

Obviously not the same trailer model, but the tanks on my Excella hang lower on one end than the other. On purpose.

The waste tanks are lower to the ground on the end with the discharge ports.

The fresh water tank is lower to the ground on the end with the freshwater drain valve.

This is because of gravity and the need to have the tanks drain.

Yup, mine too. Since the tanks are not symmetrical, and the pans are their support, the pans are made also asymmetrical. The fresh tank does bulge the center of its pan when full, but that is normal. The pan holding the gray and black has a frame member along the centerline crosswise with bolts. So that pan does not bulge.

[JCWDCW]

The tanks are enclosed in 1/2 “ or 3/4” styrofoam. You can safely put in new screws on the same centre line as the originals
I don’t se any issues other than some loose screws
The tanks are cradled in the galvanized box and that is screwed to the sub floor so as long as you can’t see any separation at the top of the box you should be good
JCW

[panamerican]

How fast do you fill the fresh tank?

Should be a slow fill. I have seen folks crank the valve wide open, the tank cannot express/displace the air in the tank fast enough as the vent hole is less than 1/2 that of the fill hose and the tank expands and eventually deforms the tank cover (similar to what you are seeing) and the floor.

[TLBIJOU]

The belly pan is not the only think supporting your fresh water holding tank. Your bellypan is 0.025" Aluminum. Your tank full of water will be over 300#. I believe they all have an angle iron frame with 3/4" plywood under the holding tank. Not sure what year your unit is?

[dznf0g]

Originally Posted by TLBIJOU

The belly pan is not the only think supporting your fresh water holding tank. Your bellypan is 0.025" Aluminum. Your tank full of water will be over 300#. I believe they all have an angle iron frame with 3/4" plywood under the holding tank. Not sure what year your unit is?

We are not talking about belly pan here. These are thick galvanized tank pans bolted to frame cross members. The tanks are not supported by plywood nor angle iron frames.

[GOUSC]

Dznfog and JCWDCW - Thanks. After reviewing all the responses from everyone, I think this explains what I’m seeing and how to address the screws. I made some ramps today to get better access 7 underneath to address the screw issue. I may add some straps for addional support if it’s something I can tackle. There are no bolts that hold up the assembly that are stripped or loose.

I do use the slow fill method but there have been times I’ve gotten distracted and there has been back flow. My hose just hangs loose in the opening (not threaded in). I just let all the excess flow back out the input until it stops. Any residual weeps out the smaller relief opening.

The timing works that after my post, someone who is knowledgeable in this area is going to stop by next week and take a look to make sure that all is normal except for the stripped and missing screw.

Thanks again to all for your comments and education in this area.

[Kodiak2006]

Jim - Thanks for posting this. I need to ck the pan on my GT. I think it has a similar bow when filled. I usually travel full since I am typically boon docking in transit. I prefer a know water source regardless (as opposed to CG water which is usually nasty). Did you make it NY to have Collin look at the FE?

[GOUSC]

Hi Gary,

Yes, I had him take care of it. See this thread, post #145, for my report of the repair.

https://www.airforums.com/forums/f44...-227874-8.html

Re: my fresh water galvanized box for the fresh water tank. I too travel with a full tank for the same reasons. A friend of mine has a 2019 GT. His driver side is also 1 1/2” lower than the curb side. However his tank does not have the bulge. He hasn’t Boondocked as much as I in the past so I don’t think he travels with a full tank as much as I do.

I do think some road debris may have causes a dent in the bottom of the galvanized box. I think I will remove the access plate / see if I can bend it back and put in some new screws.

[Ray Eklund]

GOUSC: The street side of my tank is 8” off the ground. The curb side is 9 ¼ - 9 ½” off the ground.

*****
I was working on the same plate this Summer with the head of one screw missing. The threaded portion was still secure and I did not want to drill it out, so not to drill into the fresh water plastic by error. That was an option I am avoiding. I cleaned the area and secured and sealed the edges with Gorilla Tape. The thick black very tacky tape that adheres well.

I mentioned this to my Wife and she read your post and I found it. Three screws were snug, one head was missing last year. I wanted to clean and tape it to prevent anything getting into this area over time. The plate had a slight bend put into it at the Factory, as there is a misfit in this corner of sheet metal and rivets. Maybe a 'fix' to make things 'sorta fit', but with gaps.

My galvanized metal plate is above my axle bottom, and not having any of the water tank framing, exposed below the axle like yours. I had a 3 inch lift installed, which DID give my fresh water tank clearances of: 13 1/4 inches on the street side and 13 5/8 inches on the curb side, the side towards the rear axle. But not as drastic of an angle as your photographs appear.

My fresh water tank is all above the bottom of the Dexter Axles. With a drop to the fresh water drain of 3/8 inch.

I also have 16 inch Michelins, which may give you a half inch more road clearance, if you decide to go that route.

When I removed the plate to look inside, there is a thin piece of flexible white foam that is very thin for friction of the water tank plastic to metal, versus any other purpose. Sure not for insulation for freezing...

The corner of the fresh water 'box' where the screw head was missing does not secure very well and that was the purpose of securing the area with the Gorilla Tape. This area was fitted poorly at the Factory, not from anything I did. Possibly when the Lift Kit was installed? I do not know.

I did notice that BOTH of my Jack Here plates were missing, and a slight indent and rivet missing. This would have been from the time the Dealer installed the Lift Kit. I never use a Jack to lift a side of the trailer. I use blocks under the tires to get the wheel off to rotate.

My drop is less than 1/2 inch from left to right for draining. From your photograph, yours does not look even close to what I am seeing. My bottom aluminum may have a slight cure towards the drain, which is the low drop for draining. That seems like a lot more of an angle.

I too, travel with a full fresh water tank. If you need me to check anything on my 27 foot, make a post. I will follow this thread.

[GOUSC]

Thanks Ray,

I'll keep in mind your Gorilla tape option. I'm going to get a 2nd pair of eyes look at it this Friday when they are at my house for an unrelated matter and report his findings.

[GOUSC]

I had to delay the date that the person who was going to me doing some other work on my RV until after the holidays. He has done work in this area previously and felt there was no issue with the compartment holding my fresh water tank falling. Nothing unusual in that area except for the crease and open area in the street side rear corner.

He agreed that it looked like some road debris came up and caused the dent. He suggested I remove the access panel to get a better look at it. I removed it and used some C Clamps to bend the metal enough to replace a rivet that broke off in the corner and add a couple more in that area.

When it warms up some I will clean up that area and take Ray's advice and use some gorilla tape to close up the area a little more. I spray the underbelly with Corrosion X once a year and that has gathered some road grime that needs to be cleaned off.

The guy suggested I could add a metal strap in that area if it made me feel better. If I can't do it, he can come by later and do it for me. I have the straps needed from other home projects I've done. He suggested I not remove the bolts that are already there holding up the metal enclosure box and just screw them in areas adjacent to the bolts.

Has anyone done this themselves previously? If so, what is the level of difficulty? I'm assuming the current bolts go into a frame cross member (but don't know for sure) so if you have any recommendations of the type bolts or screws to use.

[Kodiak2006]

Jim - from your original post, I have been monitoring my belly pan. I noticed it looked like it had developed more significant bowing this past year. I just completed fabrication of a reinforcement to support it. I am heading to WY this summer and wanted to bullet prof it before the next season of travel. I purchased 1.25 x .125 wall sq tubing and did a drop from a 1in angle iron attached to the OEM belly pan flange.

file:///var/mobile/Library/SMS/Attachments/f1/01/1038BA99-B093-4B93-A610-F166C415AF27/IMG_7471.jpeg

[FloydCoVa]

GOUSE , I remember Rob (RFP) over on the 23d thread posted about using plusnuts to reinforce the bolts that hold the metal enclosure box to the frame. I had to do the same to my trailer. Not sure if this could help you but you might use the same technique to add an extra strap. Look for post #’s 4004, 4007,4009 and 4015.

https://www.airforums.com/forums/f14...ml#post2422774

Just noticed this is a older thread sorry.

[Jim J]

I have a 2014 FC 30 with the same type of water tank and support. I have replaced the tank before when a fitting failed and I lost all my water. The tank has spin on fittings and they can only be repaired by someone with that equipment or equipped to do plastic welding.

The tank and supporting pan are sloped to the curb side for the water to drain out. The Plastic tank is resting on polystyrene foam which is on the bottom and sides of the pan for insulation. If you remove the inspection plate you can see the foam.

You do not need a very long sheet metal screw to reattach the plate, if you remove one of the remaining screws you will see what you need. It is a good idea to have the inspection plate secure to keep out dirt, insects, animals...

If you have a crease in your tank pan that means you ran over something or backed into something that hit the pan. That can happen if you jump on or off a curb coming into or out of a gas station or when backing into a campsite that had a log or concrete parking barrier. Especially if the site is not level.

A small crease in the pan is not a big concern as there is plenty of room inside the pan for the tank and the poly styrene insulation. Check at every corner of the pan to make sure there are no popped rivets.

The pan is attached by many large self tapping bolts that bolt into the frame. Make sure they are all in but not too tight because you can strip the threads in the frame. You can go up to the next higher diameter bolt if this has happened, but do not use a longer bolt.

Hope you do not have to take your tank out because that is a difficult job. The only reason to remove it is if you are having a leak like I did.

[FloydCoVa]

“The pan is attached by many large self tapping bolts that bolt into the frame. Make sure they are all in but not too tight because you can strip the threads in the frame. You can go up to the next higher diameter bolt if this has happened, but do not use a longer bolt.”


On my 2015 23d every other self tapping bolts were stripped. How long I don’t they were loose I don’t know. I followed Robs fix and used plusnuts to better secure the pan. Every one should check these bolts as they could be stripped from the factory. Those self tapping bolts don’t have much “bite” in the frame of the trailer. Thanks to Rob (RFP) for posting this fix.