Dump Valves - Need Help

[lebolewis]

All of my comments are about a 1976 31ft Sovereign International. The tank dump valves are the original Thetford valves. The tanks were left "dry" by the PO, but with some effort they both open and close. The Main tank (Black water) valve does not seat completely. Judging from the handle clips, it is about 1/8 - 1/4 inch from seating completely.

Problem - both valves are a little "stiff" to open and close, but the Gray water tank seals well and seems OK and I think it is good to go. The Main tank valve leaks a steady little stream.

I have done a "search" on this subject and read many threads and this is a brief summary of what I have learned. Plan A is that you make every attempt to fix the problem without removing the valve because it's a BEAR to get to. Plan B, bite the bullet and remove and repair/replace the valve.

I'm now in the Plan A stage and looking for ideas. So, all you clever, EXPERIENCED guys chime in and give me some good advice. Thanks Bill

[Zeppelinium]

I'm about to take my similar set of valves apart. Black works fine, grey doesn't seal. My only previous experience is with my Caravel--had to take the valve apart. It's a straightforward repair once you buy the new plate, but on the Caravel I only had to take down a small piece of skin around the valve. On my 31' it's a much bigger piece of banana skin.

Another advantage of the Caravel (1970 black tank only) is that you could fiddle with the grooves in the valve with a bent clothers hangar to remove jammed toilet paper. I don't think you can with the double valve and drain on the later models. I'll be posting photos in October.

[balrgn]

Other than awkward positioning it is not hard to work these. Here is a pic s you can see the inner valve

[Condoluminum]

Getting to valves to replace or rebuild is sucfficiently challenging I'd try a few alternatives before committing to that... Hypothesis is that something is dried and blocking channel groove around edge of valve where slider is trying to complete seal...

I'd consider several rounds of flushing and letting unit soak or stay wet to try and "sfoten" whatever is blocking groove first.. (May take some special accommodation of how to handle dripping fluid...)

Several other threads advise use of coat hangar or other long stiff wire as a way to chase or clean the groove.. I'd try that, with possible addition of extendable mirror or other means to see blockage..

Another option might be to use pressure washer wand and see if high-power spray might dislodge blockage. I'd also try Thetford valve lubricant as well...

John McG

[lebolewis]

The bent coat hanger or similar device is the most likely candidate for successfully getting the crud out of the gate track, if that is what is causing the problem. I hope it's not part of the seal that is stuck in there. However, I cannot figure a way to get to the valve where I can "see" or "feel" what I am doing! The toilet hole is the closest opening to the valve but I've never had the toilet off the tank and I don't know how much trouble it is to take off....and then put back on! Nor, do I know if the opening there is large enough to get your hand and part of your arm into, like up to above your elbow. Anybody got any experience with that? Trying to come in from the outside drain outlet is too great a distance. However, I do plan to try the high-pressure hose and spray technique and I think I can do that from the outside drain opening, if I can wiggle and work the hose up to the valve gate. Got to go purchase a small brass sprayer for the hose. I haven' tried that yet because I am still soaking everything and trying to soften everything up. More later........Bill

[carnegie1935]

I had the same problem on our holding tanks. I read a post about putting liquid laundry detergent and a gallon of water into the toilet and drains after each dumping. I use about a cup of detergent. I also put vaseline on the handle shaft and all dripping has stopped. The shaft now pushes all the way in and the clips will latch. I was dreading the rebuild and now It seems to not be necessary. Good luck to you.

Kay and Roy

[lebolewis]

Like Kay and Roy, I too am hoping for an easy solution to this problem. Unless it's a piece of the valve seal that has folded over and gotten in the valve track seat, then I think I can eventually dissolve the crud or pressure blast or float it out of there! I visited Lowes today to get some things and looked at a gallon of Muriatic Acid.....the stuff they used to clean swimming pools, masonary and other things with. They don't use it on pools any more....it's to dangerous. It's very corrosive and you have to be very careful using it. One of the threads on this site recommends mixing it with water and using it to clear gate valves......but I decided to pass for now. Tomorrow, the high-pressure water blast! Bill

[Zeppelinium]

Originally Posted by lebolewis

The bent coat hanger or similar device is the most likely candidate ... The toilet hole is the closest opening to the valve but I've never had the toilet off the tank and I don't know how much trouble it is to take off....and then put back on! Nor, do I know if the opening there is large enough to get your hand and part of your arm into, like up to above your elbow. Anybody got any experience with that? ...
........Bill

toilet hole isn't big enough, since the tank is shallow you can't get your arm in far enough to bend your elbow. I don't know about your layout, but my toilet is on the other side of the trailer from the drain.