'65 Caravel dump valve replacement step by step

[kevinkatz]

ok so here goes---started this evening to replace the thetford black tank dump valve on my 1965 caravel. i am documenting well because when i looked for information on the forum i was unable to find much.
let me first say that this is not for the feint hearted. i have quite a bit of experience building a few hotrods and did most of the work on renovating my caravel. the biggest issue is that everything is rusty and degenerated.
it is not impossible by any means but you have to be a little aggresive.

first images show where we start. you have to make access removing belly pan by drilling out rivets. i also use a die grinder A LOT. you will see it used here on rivet heads and later on the valve itself. i use it with a compressor.

[kevinkatz]

next you need to remove the split pin out of the lever that goes into the bumper. usually this is very easy. mine disintegrated and got stuck in the metal. i had to work hard using the die grinder, and punches to get it out. now everything is exposed.
note that the 4 screws holding the valve to the base of the black tank are all rusted. there is no way to remove them. i couldnt grab hold of them or cut a screw head.
so i decided to grind them away with the die grinder.

[kevinkatz]

the bolt grinding didnt go well so i decided to attack the plastic of the valve and grind it away in the hope of dropping the valve. it worked well. the the valve came off with not too much encouragement.
now you can see the screws left in the black tank. of course these HAD to come out so i carefully used a vice grip. not easy but possible.

[kevinkatz]

i am showing close ups of how i ground away the plastic for relatively easy removal.

i am also showing the top of the valve with dimensions. note that i had closed off the grey tank insert but will open it with the new valve.

now i a have a couple of questions.
the thetford valves that i see on line are not flat like mine. they have raised areas around the screws. it appears that i may have these fiberglassed into the base of my tank. is that possible?
secondly could i use a valtera valve now that i am at this point? is there one with the same dimensions that will just bolt on?
i will continue this step by step replacement when i get my new valve and finish the job.

[Cannonball]

Ok, you are an over-achiever! You leave the camp at 10:30 am, and less than 10 hours later you are knee deep in this major project. Good luck. Good camp, by the way!


Cannonball, Deep in the Heart of Texas!

WBCCI #4387, Air #84080

Sent from my iPad using Airstream Forums

[kevinkatz]

I ordered my parts from Steve at Vintage Trailer Supply. He is a good resource on this issue and has parts in stock.
There are a couple of options for the valve. Some allow you to attach your Thetford collector. Others, like the one I bought, have a 3" pipe coming off it. I could have bought a valve with the same connections to my collector as my old one. I chose not to do that because my Thetford collector had been glued on to the old valve and I could not reuse it. Some Thetford collectors are still available but there are less options.
I use a Sewer Solution which attaches to the Valtera system. I could have used Thetford because there is a readily available, cheap adapter from Thetford to Valtera. In the end I decided to switch to a Valtera collector. So the black connectors that you see are all Valtera.
You can see from the images that there are two options for attaching the Valtera collectors to the valve. One fits directly to the valve, the other uses a connector and gives more length. It depends on how low, or high, you want your valve.

[kevinkatz]

Here you can see the two options for putting the collector back together. The difference is the elevation. It is important to understand that the plastic used in these valves and collectors is ABS plastic. That is different from PVC that is found in all hardware stores. In Texas you can't buy ABS. The only place you will get adapters, connectors and glue is at RV stores. You have to use ABS cement. BTW ABS is always black, however the white Thetford fittings are ABS.
Now it is just a matter of screwing it back on to the bottom of the tank. The valve came with screws that I may use. They may be a little thinner than my old, rusty screws so I may buy some thicker stainless screws. Be carefull that they are not too long or they will damage the black tank. I will post the reinstertion.

[kevinkatz]

Firstly look at the adapter on the bottom of the black tank and get it clean.
Then I decided to mock it up before gluing and was I happy that I did that.
The screws that came with the valve worked well. You can see one in place holding the valve. The valve opening extension needs to be connected with a split pin.
Then I put my Sewer Solution on to see if I had enough clearance using the shorter collector set up without an extension. I just figure that with less parts there is less to leak, and that it is less likely to get hit by road debris. It may be more difficult to attach the sewer hose. May change my mind before gluing. Anyway when I put on the sewer solution it was at the wrong angle and the inlet water hose was hitting the metal protector. Just rotating the collector a bit makes it work very well.
As an aside I have shown how I handle my grey water at present. I put a 45 degree angle on the grey water pipe. I can either let it dump on the ground or just push in the hose adapter that I have detailed in the picture. It is made from very cheap, readily available PVC. The hose can either direct the water away from the trailer, into a blue tank or down a sewer.

[kevinkatz]

Firstly the gasket on the valve is upside down in the pictures. The bevelled edge needs to go on top.
Fill your tank with water to test before closing up the bellypan.
I sprayed a whole lot of household insecticide in the bellypan while it is open.
I replaced all the insulation that I could get to.

[Peter417]

I'm dying to hear the ending.