Community Forums

Steve 716 · 01-21-2021, 06:57 PM

If you use flex seal tape it will seal everything it covers. I used it to seal an opening under my toad front facia and it sealed. I picked up a piece of trim and it punch a hole in my wheel well and the hole started growing. I covered it with the tape and no problems since.

chuckftboy · 01-21-2021, 07:37 PM

I own a sheet metal fabrication shop and my first choice for replacing the aluminum sheets would be Paint grip, 24 ga. sheet metal installed with steel pop rivets

Its sold in 4' x 10' sheets and paint will adhere to it easily for corrosion protection. Relatively inexpensive although sheet metal is up about 30 percent since the first of the year. Any HVAC or sheet metal fab shop should have it available

STEVE-JUNELL · 01-21-2021, 07:47 PM

Years ago I have a 2005 Essex I did this project on and I went to a local pole barn metal shop and they had some painted flat stock I used that for the first layer then the pink foam and marine grade plywood worked great

Delacroix · 01-21-2021, 09:30 PM

I greatly appreciate all the replies on material selection. This is definitely a job you don’t want to do twice. I keep thinking about how many newmar coaches out there have this identical problem and people just don’t know. I bet newmar is aware of it.

MarcM · 01-22-2021, 05:40 AM

Our 2018 Ventana LE went into the shop 8 months after we picked it up new. While crawling around under it after returning from a 5 week trip to the SW of the US I was shocked by how much corrosion there was on the frame, accessories and everything else that was exposed to the weather.

Our dealer (Diamond RV in Mass, now Gander RV) really took this seriously as a warranty claim and put one of their new shop employees on the project to undercoat EVERYTHING properly. They said he looked like an old fashioned chimney sweep when he got done!

We purchased a Newmar based on the alleged quality of the brand in comparison to others and we ordered it new to meet our preferences. While we love traveling in it, we have found that the quality reputation of the brand is not what it once was, and sadly now given new ownership of the brand, doubt that it is going to get back to where it once was.

calendarboy · 01-22-2021, 08:29 AM

If you have a motorized boat, it will have sacrificial magnesium attached. The magnesium is highly reactive and will lose bits more quickly that the other metals.

Using steel 2x4s and 2x6s, etc. requires adding sacrificial magnesium.

The best anode in a water heater is magnesium which is much more reactive than aluminum. The only thing better would be TWO magnesium anodes.

Back in the 50s and 60s JC Whitney sold kits for adding sacrificial anodes (magnesium) all over cars.

I think we should consider adding sacrificial anodes to our RVs—escpecially where there are disimilar metals, water, and possibly salt.

Ron75 · 01-22-2021, 08:52 PM

I have a 1998 Dutch star from Florida same problem basement Steel pretty much completely rusted let's go to the beach with the motorhome NOT.
I bought new steel for outer and diagonal support from Newmar expensive but good repair I have my own welder and cut and welded new steel after painting, a lot of work.
I completed the wet Bay but still have to do the rest of the basement not looking forward to it took me two months to do the wet Bay pulling 112 gallon freshwater tank out and then cutting old Steel and some of the down supports terrible job, time consuming, confined space work. I'm 75 and crawling around under there in and out hundreds of times to cut this measure that and see if it fits hand clapping and welding in place.
Never take your motorhome or camper trailer to the ocean.

Delacroix · 01-23-2021, 10:11 AM

Firedog: What sealant are you using during your repair. Also, if I place lots of sealant on my stainless steel screws, do you think it will be ok compared to the rivets. I doubt the pull rivets are as good as you are using. I’m actually thinking of using the flex seal in caulking tubes, placing lots of extra so I see it extrude. I’d really like to get your input as I’m sure planes require something that holds up over time. Thanks

RCC · 01-23-2021, 11:52 AM

I'm following this discussion with LOTS of interest, because I've noticed the aluminum sheeting on the underside of the water tank basement on my 2012 Thor Tuscany is deteriorated just as Delacroix and Firedog3722 have described. I haven't done a "full autopsy" yet to determine if I'll need to replace any of the wood structure. I, too, am concerned with what to use to replace the substandard aluminum skin that Thor used. With much anticipation, I read up on the suggested FRP (fiberglass reinforced plastic), but noted it is for interior use only -- so that option is out. Thanks to all of you for the detail you're giving us as you work through this. I think I'll be following in your footsteps in the immediate future, and I appreciate learning of your processes!
Roger Craig

Firedog3722 · 01-23-2021, 06:26 PM

I was working on replacing my Magnum MS2812 today and that took most of the day so didn't accomplish much in the wet bay. Replacing a battery temperature sensor is not easy.

However, I did decide on the sealant I'm going to use. I talked with a few (4) auto repair shops Friday and told them what I thought the issue was and how I wanted to do the work. Three of them suggested a 3M product called 3M - 00550 Dynatron Auto Seam Sealer Caulk. This caulk comes in a tube and you can get it at Autozone for $15/tube. In my area the stores only stock one tube, they got me others by 1pm the next day. I chose this caulk because it is not supposed to get hard. It remains flexible after is cures. Thought this might be important with all the talk about how our coach chassis' flex. It also is supposed to adhere to paint/plastic/alum/steel and other surfaces. It is able to fill large voids and is paintable in a short amount of time.

Work I was able to complete today was rough cutting the replacement wall piece and getting it fit across the the entire wall, side to side. I still have some minor trimming to do tomorrow, but the basic wall is cut and fits. Picture tomorrow.

Things to be aware of when you do this project are that you don't have to do the entire wall, I'm not and you will see a picture tomorrow. You just need to replace enough of the wall alum to get overlap with good old alum so you can seal it, and fasten it. Unless your wall is entirely gone I would suggest only replacing what you have to. I was going to do the complete wall but after getting into it I found the areas around the frame beams to be sealed very well and I didn't want to disturb that seal. My new wall piece is 95 inches long (just short of 8 ft) by 18 inches wide. Check all the welds. I found a broken weld at the driver side rear corner of the bay where the vertical support meets the lower supports for the wall across the back and the support that goes from rear corner to the front corner under the door you open to operate items in the wet bay.

I'll say again, it surprised me at the number of items fastened to the rear wall with long screws that had penetrated the complete wall, wood and the alum, another potential water entry point. Be sure you only use screws that are long enough to go thru the mount point of the object you are attaching and then some of the plywood (or other item you use). That reminds me, to fasten the new plywood to the alum wall I think I'm going to use liquid nails. I have to read what it adheres to, making sure it will stick to my new, and the old, alum in the back wall.

Bucky573 · 01-24-2021, 09:53 AM

I replaced one section of mine that came off going down the road. The metal came loose due to corrosion. The foam insulation remained in place undamaged.
I used the FRP sheeting from Home Depot and self tapping screws. I did put a bead of silicone on the frame before attaching for waterproofing.
I raised the coach up on jacks to give me more room to climb underneath.

Delacroix · 01-24-2021, 10:17 AM

Firedog: I just read about the properties of the sealant and I’m definitely going to be using it. Greatly appreciate you pointing out this material. I’m also not replacing the entire back wall board or aluminum. I’ve cut back to good board and stopped. Same on the metal. I’m about ready to start my priming. I really look forward to starting to put this back together. It’s been a major job. Luckily I’ve got a heated building to be working in. I live in WV and it’s been 20 some at night. My building temp is 60 so I should be good painting.

Firedog3722 · 01-24-2021, 07:48 PM

Delacroix glad to help.

As promised here is the first rough fit of the back replacement wall. See first photo below.

Next thing I did today was to align the back wall and stabilize it where I wanted it. I've have actually it raised off the angle bar about 3/8 inch. Reason was, IF some water got in there I didn't want the wall sitting in it. I drilled holes thru both the new wall alum and the old wall alum where I wanted the rivets that will hold the new wall. How I attach at the bottom to the angle is still being discussed, more to follow. See the picture in row one on the right side

I cut the material for the forward section, first (bottom) layer of the new floor. This is the material I ordered from Newmar. I thought it was Styrofoam laminated to Aluminum. I now believe it is a thin Stainless Steel, a magnet sorta likes it. It took quit some time deburring the cut edge making it smooth and removing the cutter marks. There is also a layer of some type of paper on it. I'm going to call Newmar tomorrow to see if this is special paper (water resistant) and I'm supposed to leave it on, or it is just for shipping and I need to take it off.

The thickness of the Styrofoam on this product was approx. half of what I took out. I'm going to have to purchase a sheet of 1/2 - 5/8 thick Styrofoam from Home Depot to fill the extra space. You can see the space I need to fill with extra Styrofoam in the first photo in the second row below. The second photo in the second row shows the narrower piece of the floor set in place to check the fit.

I thought that I had ordered too much of the 1st layer material. What really go my goat was the fact that one piece of the floor material is not what is required, if you want close tolerances. The forward section of the material measures as 22 1/4 inches. The rear portion that sits right in front of the rear tires measures 26 1/4 inches. The length of both those pieces is near 77 inches. You can not get both those pieces out of a 48 x 96 piece of material, it is short by 1/2 inch but blade width. I knew this before I cut the first piece. I cut the 22 inch piece where I wanted it 22 3/16 and then dropped in the wider part. The gaps between the edge of the angle iron and the material on the wider rear piece were just to big for my liking. So I'll cut my wider piece out of the second sheet I have.

Firedog3722 · 01-24-2021, 08:00 PM

I forgot to mention a broken weld I found. It was at the rear, drivers side junction of the vertical support, door seal support, and the angle that runs across the back of the rear wall. See photo below. Because of the condition of the metal my hobbyist welder friend doesn't have the welder needed to weld this. So drilled two holes, one into the rear crossing piece and wet bay door seal support, and another into the vertical support and the rear angle. I forgot to take a photo of that correction today. Next visit I'll take a photo of the fix.