And another Plumbing issue!

[DryFly]

I'm finishing up replacing the belly pan on my '73 Argosy 20' TT and decided to check the functionality of the toilet before I closed it up - I'm glad I did. I found a leak where the black 4" drain elbow attaches to the drainage system. I want to replace the Thetford valve (part # 08706) but I can't locate the "T" that sits below it and onto which the 4" elbow attaches. I called Thetford but they were no help. I'm surprised as this looks like it should be a part for their system. Here's a photo - any suggestions?
Also, the black drain line sits awfully close to the ground and looks to be an opportunity to shear off waiting to happen. Is there a way to raise it?
Thanks as always

[Jammer]

The more unusual Thetford valve parts have been discontinued.

Your best bet is to patch the part you have by cleaning it thoroughly and applying ABS cement. If the crack is large, you can reinforce the repair with fiberglass cloth, by applying cement, then the cloth, then more cement. Wear nitrile gloves.

Otherwise you can switch everything over to the Valterra system:

RV Products & Accessories

[TG Twinkie]

I believe you will find it is not 4" but 3" fittings.
Does the dump valve attach to the bottom of the tank with a hose clamp?
I would try to repair the crack as long as the valve seals are good.
Otherwise, I would look at an upgrade.
If I were to replace it. I would attached a 90 street el to the tank and put the dump valve in the horizontal line. You can use a clean out fitting to bring the grey water line in down stream from the dump valve.

[idroba]

My 20' '74 Argosy was either plumbed differently or modified by a PO, but I would say that it probably is plumbed like TGTwinkie imagines yours could be done, with a vertical valve rather than a horizontal one. Oh, mine also has a gray water tank on it, yours may not.

I have never had the belly pan off so I can't tell you how it is really done.

[DryFly]

I removed the Thetford valve along with the 90* waste line - TG, you are correct, it is 3". Here's a photo of the fitting that is adhered to the tank. The Thetford Blade Valve was attached to it using 4 very rusted screws. I like the idea of a 90* street el, but I can't see how to fit one. I'll keep working on this - I would definitely like to go to a Valterra system, but I don't think the hole pattern is the same as the Thetford. Ideas?

[TG Twinkie]

I would send the latest pic to Thetford along with the others you took and see if they make anything that will work.
The flange device in the last pic looks like it is glued somehow to the tank. Is this true?

[Beaker63]

Hey Dryfly
The vintage airstream site (under restoration ) has directions for converting to the Valtera valve. Did ours and it works great.
Tim

[DryFly]

Originally Posted by Beaker63

Hey Dryfly
The vintage airstream site (under restoration ) has directions for converting to the Valtera valve. Did ours and it works great.
Tim

Tim, do you have a link? Also, were your connections similar?

Thanks
Dale

[Beaker63]

Hey DryFly
Its vintage airstream.com
I have only a black tank and the connection were the same. The only problem was that the
1/2 inch aluminum plate needs to be larger than listed. I think it should be 6x6 inches.
Tim

[DryFly]

Originally Posted by Beaker63

Hey DryFly
Its vintage airstream.com
I have only a black tank and the connection were the same. The only problem was that the
1/2 inch aluminum plate needs to be larger than listed. I think it should be 6x6 inches.
Tim

Wow, a whole new site I never new existed. This will be worth hours of exploration. What a great community. Thank you (I'm trying to avoid expanation points)

[DryFly]

I wanted to use a Valterra valve, but in the end I decided to replace the existing Thetford valve with a new Thetford valve. This is because the Thetford fitting that is attached to the blackwater tank is REALLY attached to the blackwater tank, and I would have had to remove the toilet and blackwater tank, which I was loath to do. Thetford is evidently gradually discontinuing these valves so eventually someone (hopefully not me) will have to do the big job.
One of the really good things about this older system is that it is based on standard plumbing parts. All the fittings are readily available at hardware stores. You can't say that for Valterra.
By using a standard 3" elbow with a built in 2" tee, I was able to raise the drain line by about 2". An issue with the original drain is that it sits pretty low to the ground, providing an opportunity to back over some obstruction and potentially causing damage. This is what probably happened to my system, thus requiring the repair.
Sorry for the long post.
Here's a photo of the finished product - prior to the last new piece of belly pan going on.

[Michigander]

Nice job. Looks like a neat installation.

[TG Twinkie]

Good looking install.

Just out of curiosity. Why is ABS pipe used on RV's in most cases? Is it cheaper than PVC?
My Argosy has both. All of the pipes going into the holding tanks are ABS. But everything leaving the holding tanks is PVC. It is all original.

[DryFly]

Originally Posted by TG Twinkie

Good looking install.

Just out of curiosity. Why is ABS pipe used on RV's in most cases? Is it cheaper than PVC?
My Argosy has both. All of the pipes going into the holding tanks are ABS. But everything leaving the holding tanks is PVC. It is all original.

Thank you TG.
As I understand it, PVC is quite a bit stronger and more durable than ABS. ABS is now only used for drainage and venting, not for water delivery (I think a component of the ABS can leach into the water).