Black tank plumbing and other things

Black tank plumbing and other things - Printable Version

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Black tank plumbing and other things - BusNit - 01-30-2023

I have replaced my black tank plumbing in favor of a heavier duty dump valves. The original on my coach were Thetford with the non standard 2 hook clamp. At one point there had been a tank leak in the previous owners possession. They had it fixed but it seems the water damage had leaked under the fiberglass bay liner and on top of the steel chassis floor. The water had no where to go so it ate all the metal away. It was very well hidden under the spray foam. I am at a loss in dealing with something I was not expecting. Seems like one step forward and two steps back. I was excited to upgrade the plumbing and added a hose connection to wash out the sewer hose. How I discovered the rotted mess underneath is from the water tank bulging and bending the support that was installed. When I checked the support, it was loose and flexed. This told me the anchoring bolts were not doing their job. I dug the foam around them only to discover the rotted mess of earthy brown decay. I am not going to pull the tanks but instead scab some galvanized 12 gauge plate between the 1.5" square tubes once I clean off the rust. The foam did a good job of keeping the water hidden until it was too late where it then found a path through the protruding bolts. Still wondering how the water got there. All seams are well sealed.

RE: Black tank plumbing and other things - Jack Houpe - 01-31-2023

Simon I use a product from Eastwood which you spray on rust and it turns it into a hard coating over the rust, I use it on my cars and one car has had it on the frame 20 years and looks good as the day I put it on. Your work is superb!

https://www.eastwood.com/eastwood-black-rust-encapsulator-paint-over-rust.html

RE: Black tank plumbing and other things - BusNit - 01-31-2023

Thanks Jack. I checked and they are out of stock. I’ll find a weld through galvanized spray and paint it later

RE: Black tank plumbing and other things - BusNit - 02-01-2023

I cut out the worst portions of the metal and used a grinder to remove the surface rust from the main runners. The main runners are in excellent condition considering the amount of rot. I found evidence of some kind of OSB wood that was used which had some kind of clear coat. Only the clear coat remained and is stuck to the bottom of the water bay liner fiberglass. I found no other wood as it had so disintegrated. I put in a pre-cut galvanized sheet which will get welded as a filler. Not sure what to use as a 1/2" gap filler where the wood once was. I may put sections of 1/2" angle welded on edge. Still deciding on that. (An air gap would be excellent for any possible future water leaks)

RE: Black tank plumbing and other things - Jack Houpe - 02-01-2023

I used avantech flooring but it's 3/4". As always you do a great job man!

RE: Black tank plumbing and other things - hypoxia - 02-02-2023

You're doing a good job with what you have. The Eastwood product is probably the same as POR15 https://por15.com/ which is a great product. I can get it at the local auto paint and body supply house.

RE: Black tank plumbing and other things - Richard - 02-02-2023

There are a number of things to consider in this project. Maybe you are aware. First, welding galvanized can make you sick. Second, you cant make long runs at a time with the welder .Short stitch welds with plenty of cooling time OR you will melt the floor above the patch. Third, and I understand why, you are building in the reverse order that it was originally built, so sandwiching anything in the layer where the osb was subjects it to the heat of the weld.

Just an idea. Bring the scab to the lower edge of the framework. Predrill some holes in the patch, and use door and window frame foam to fill the space above the patch applied through the drilled holes.

RE: Black tank plumbing and other things - BusNit - 02-02-2023

No worries Richard! I have welded since I was 14 and although not a pro, welds do get proper penetration and look half ass decent. I used synthetic gate slats which fit perfectly as a space filler and primarily over where bolts protrude through the tank supports to alleviate crushing the new steel. Galvanized steel is my specialty. With proper ventilation, it will be a repair I will never have to address again. Sold a skoolie that I used galvanized sheet on a roof raise. Built a shell and sold it for 40k to buy this coach. That said, I always used a large industrial fan to blow the weld fumes away. Also I never weld galvanized in an enclosed space such as a garage. I have a Millermatic 210 and a newer inverter 215 which I love. They can handle long passes at 25% capacity. Much more flexibility on wire speed and metal thickness power. Haven't had it go into cooldown mode in my 2 years of owning the 215. I do/did small stitch welds as it isn't necessary to get a full perimeter weld. As I mentioned on the FB Newell group, this coach is not economically feasible to remove the entire contents of the water bay for this type of repair. I will never get any returns on investment for this repair as it was cosmetic and not structurally deficient. I have $340 in materials not including my labor so far. My wife misses me on weekends since I am always outside doing something with this coach. Haven't looked on the water heater side or under the additional house battery compartment yet. Newell puts a rubber liner over the steel in the generator blower fan area which leads to rot. I escaped that debacle with only pitted steel. (No more rubber liner) Same with the basement A/C area. Removed the rubber liner. I do have window foam to finish this off and then seam seal the unstitched edges finalized with Por15 and ridgid polyiso board.

RE: Black tank plumbing and other things - Richard - 02-02-2023

I didn’t mean to question your ability or experience. It’s tough to know how much someone else knows. I erred on side of safety. I didn’t want you to get sick or burn down the coach.

RE: Black tank plumbing and other things - BusNit - 02-02-2023

Oh, I didn’t take it that way and I know you are truly in the right mind to ask! I think I posted on the FB site about welding Galvanized and that I haven’t died yet! I caught so much flack over my pit on some of the bus forums (not the Newell one) that I took out all the pics and quit sharing. I mean, OSHA was thrown in the mix and deadly explosions will eradicate me while working outside and under the bus. I do love to weld but after the skoolie project, I didn’t want to run not even an inch of welding wire. This coach had its defects but the rot under the bays really put me off. I was not going to go into full on restoration mode as the damage seemed limited to what I stripped out. I can’t fault Newell for using what materials was available to them at the time of manufacture but I certainly hope that todays materials and synthetic composites would be used that fare better in wet environments.