Access to drain for both waste tanks

[PeterD]

Do I need to remove the aluminum underbody to see the drain pipes on a 1983 Excella 27'?

[Bill M.]

On our 1988 center bath models you need to cut a hole in the big galvanized cover beneith the tanks and the drain valves. You cut a square or rectangular hole about 2' feet on a side directly sideways to where the drain valves are. You have to be very careful drilling and cutting in this area because you do not want to hit the tanks or lines. I used a stop block on the drill and used a nibbler to cut the galvanized metal. Better might be a small disc grinder. Nasty job in a tight spot if you do it yourself. But the valves and plumbing were easy after the acess. Covered it up with a piece of alum and sheet metal screws. Airstream does it the same way. If you have a rear bath model then I do not know how the tanks are located or accessed. It is about $1000 if Airstream does it.

[dbj216]

I replaced the two drain valves on my 86 Limited center bath. The tanks are supported by the "tank cover" or tank pan behind the axles. I took the plastic valve cover off, and then dropped the tank cover, maybe 16 or so rusty hex head sheet metal screws. The tanks need to be empty of course. Once the tank cover is down, the tanks are hanging by their connections to drains, toilets, and vent pipes.

Many folks do cut an access "hatch cover" in their tank covers for easy access. It does make the job a bit easier as long as you don't cut the tanks.

David

[PeterD]

I appreciate the info from both of you.
Cutting it out with a grinder sounds like the safest.
Pete

[karisk12]

How did your drain repair go? I am going through the same with my recently acquired 1981 Excella II 25 rear bath. The rear underbelly skin on mine is aluminum. It was corroding badly at the mounting bolt locations so I removed it. Seven bolts on each side and just a few rivets across the front and rear. once removed access is easy to the drains. Also found out why the tank level indicator wasn't working. PO cut the wires for some reason. I also had a bit of surface rust on the frame so I dropped the gray tank and applied POR-15 to the frame areas. I'm planning to replace the Thetford valves with Valterra. I haven't figured out exactly how to seal up the assembly at the tanks. My assembly looks like the one above except the gray water pipe is smaller than 3 inches. It has a reducer of some type. My black water tank has a crack along the top of the outlet tube. Going to try J-B Weld Plastic there without removing the tank then use a good plumbing putty I guess. Is your gray water outlet 1 1/2 inch or 2"? Kind of a puzzle right now but I'll be glad to have it all new. For the belly skin I bought a sheet of 5052 5 x 10 for $73 at Coast Aluminum in Phoenix. I took it to Mesa Sheet Metal and David cut and bent a perfect replacement for me for $15. I'm very happy with that.

[dbj216]

Hello karisk12. Welcome to these Air Forums. Looks like you are tearing right into your new 81 Excella. Good for you. That's the way to get to know your trailer inside and out.

I think a wise decision to replace your old Thetford valves with the Valterra. That's exactly what I did. My trailer is a mid-bath so it has different tanks than yours does.

Belly pans corrode due to galvanic action between the steel frame and the aluminum rivets holding the aluminum in place. I replaced my belly skins with the 5052 like you are doing. Belly pans are not structural members of the trailer, they just keep some water out and the heat in.

The typical connection of ABS piping to the polyurethane tank is sealant and a hose clamp. Some gray water tanks have 1 1/2 drain plumbing due to the fact that there are no solids in the gray water. But my tank and drain manifold was all 3" piping. It looks like yours is too. Valterra sells several different types of "connectors" that bolt to the valve itself. It is a nifty design. So you can get male or female connectors in either 3 inch or 1 1/2 inch. Most RV stores carry them, or you can order on line of course. I just duplicated what the factory had done.

The waste water tanks are polyethylene plastic. It is unusual for a crack to develop as the material is so ductile. It is also a thermoplastic, meaning it can be "welded". Most adhesives will not adhere to polyethylene. Sealing your cracked tank would involve an large electric soldering iron and a stick of polyethylene. You heat the crack until it gets soft, and then heat and push in the stick of material and let the heat fuse it all together. It is rather like brazing, but at much lower temperatures. You might be able to find someone who has done it before in your area. The bottom line is your tank is repairable.

I attached a couple of photos of my drain manifold and Valterra valves. After three years, they are leak free.

David

[Siegmann]

Dbj, for the hose clamp connection at the tank, what did you use for the sealant?

[Glenritas]

BTW one should use black ABS plumbing with the Valterra valves.

The best thing about having a 3" outlet on the gray tank is how fast it will allow the tank to empty, seconds as opposed to minutes .

[dbj216]

Originally Posted by Siegmann

Dbj, for the hose clamp connection at the tank, what did you use for the sealant?

There may be several that will work. I used butyl caulk as that was recommended by my tank supplier.

glenritas, you are right. I should have used ABS piping, but I was used to using PVC on drain lines and thought it might be a bit stronger. I did use ABS on my Trade Wind with no problems. They make an ABS to PVC adhesive that seemed to work fine.

David

[karisk12]

Thanks for the comments. I started this new thread on my repair. I tried to plastic weld the outlet while still installed but it didn't hold up. I guess I'll have to pull it and take it to a local professional. Was hoping to avoid that job.