Holding tank Valves

[zadaschwartz]

Hi again, Does anybody have any experience in replacing the grey and black holding tank valves? I believe they are called Thetford Valves. I have a 26 foot 1976 Argosy. My tanks are located in the back of the trailer as is the bathroom. My tanks are in good shape but the valves leak when closed. Any thoughts are appreciated.

Zadaschwartz

[tphan]

hi zada- Repair kits, with new O-rings, gaskets, and such, are available from Thetford directly, if you want to go that route. Their phone number in Indiana is 219-294-6491. The re-build kit I bought for my '72 was only $7.69, part no. 09872. (This was for the black tank). Or you can just install a new valve assembly. Either way, you'll probably have to remove the tank, which involves getting the belly-pan out of the way. Good luck- tim

[Janets Husband]

Originally Posted by zadaschwartz

Hi again, Does anybody have any experience in replacing the grey and black holding tank valves? I believe they are called Thetford Valves. I have a 26 foot 1976 Argosy. My tanks are located in the back of the trailer as is the bathroom. My tanks are in good shape but the valves leak when closed. Any thoughts are appreciated.

Zadaschwartz

Yep. It's not too bad the hardest part is gaining access to them. Thetford is the brand name. I have found that dropping the back section of belly pan is the cleanest way to do it. If the pan has not been cut before, cut it side to side at a rivet point. Bolts in the bumper can be a bear you'll want to remove it. Drill out all pop-rivets and it will slide out. Some people will cut a access hole in the belly pan to do this job, but I like the belly pan section removal. The valves are straight forward in there repair or replacement. Take them apart and give them the once over, and if you are not happy with the scratches in the slide or housing, replace the valve don't rebuild. It's far more work to get back at the valves a second time.

[Zeppelinium]

I vote for the access hole, providing you've got a spare piece of aluminum to make a new cover with overlap (or you could make new gussets along the edges of the hole, then use the original piece).

Cutting the belly pan along a rivet line will make it difficult to re-secure. The rivets are in the frame cross members, about 1/8" steel that will not be the easiest thing to drill, plus the flange is not very wide, so a seam there is a problem if you don't have enough skin to make an overlap.

I don't know about your particular installation, but in the Caravel and Overlander the valves were accessible without having to do anything with the tanks.

Zep

[lebolewis]

For what it's worth, here is another actual experience. I have a 76 31ft Sovereign International. Getting to to the valves is a bit troublesome, you have to cut an access hole right under where the valves are located. However the bigger problem is getting the valves off the holding tank and the 3" sewer pipes. The valves are fastened to the holding tanks with 4 big screws. If the screw heads are badly rusted, then they can be very difficult to remove. Further, in my case, the valves are glued to the 3" sewer pipes. They have to be cut off. That requires you to replace the old valves with new valves ($55.00 each). And.....you will also have to put in a new coupler to the sewer pipes or possibly replace an elbow, depending on how your sewer pipes are installed. In my case, I had to remove the rear bumper and remove the plastic hose caddy and cover just to get at the sewer pipes to complete the installation. It cannot be done any other way. I hope I never have to do this again.

My valve leak was caused by the gasket in the valve having a big chunk of rubber missing.

Good luck, Bill

[GlenCoombe]

This is another fine example of why some of us prefer our AS motorhomes. Not only is my black tank valve completely exposed but I can work under the bus without having to jack it up.
Once you have access you should be able to disassemble the valve for rebuilding. Take a good look at the connection push/pull rod for corrosion. Mine broke and required another rebuild of the complete valve.
As you put it all back together use a good amount of valve lubricant to help the slide.

[Van]

I've done both of mine too. As mentioned, the most difficult part is getting to them.

I bought the gasket replacement kits and took mine out, cleaned them up and replaces the gaskets. Reinstalled and worked like a charm.

[LI Pets]

Did mine from the top if this helps?

You can see a hubless adapter where I had to make a cut to get the whole thing out.

[nickcrowhurst]

I recently overhauled the black tank dump valve on my side bath Excella. The valve had become steadily more difficult to open and shut over the years, and I knew I would eventually have to do the repair, and do it while living full-time in the trailer. Therefore, a year ago I cut the inspection hole in the belly pan, and fitted a hatch with 25 stainless roofing screw. A week before I planned to do the repair , I removed the access hatch, and noticed, as stated in the Airstream manual, that the 4 securing bolts on the pipe clamps securing the valves all point upwards. This is clearly to make it easier in the factory, as the floor is fitted after the dump valves are installed. Thank you, Airstream! The manual suggests a short open-ended wrench to loosen these. This is quite impossible, as the securing nuts are deep down between the valves and the tanks. I found that the necessary tools were a Standard Deep Socket set. The sizes required are 7/16 inch for the tank to valve bands, and 5/16 inch for the two bands on the rubber coupling. Mine were from Wal-Mart, a Stanley Standard Deep socket set, # 85-730, 6 pt, 3/8th drive, with a 6 inch ratchet and a 3 inch extension. I was just able to get this and my hand above the clamps and loosen them, after spraying the threads with WD40. I swivelled the clamps round so that the nuts were easily accessible, and then re-tightened them.
With this preparation I was able to complete the repair while my wife was out at the store one morning, without disrupting the use of the trailer.
The problem with the valve was that it was completely covered with a hard rock scale, presumably from using the water in Florida, a limestone area. Any ideas on preventing this? How about removing the scale without demolition? Hydrochloric acid on the pluming system would be a bit fierce, I suspect.
Nick.

[Zeppelinium]

Originally Posted by nickcrowhurst

...The problem with the valve was that it was completely covered with a hard rock scale, presumably from using the water in Florida, a limestone area. Any ideas on preventing this? How about removing the scale without demolition? Hydrochloric acid on the pluming system would be a bit fierce, I suspect.
Nick.

LimeAway, used for getting scale off of glass shower doors?

Zep

[nickcrowhurst]

Originally Posted by Zeppelinium

LimeAway, used for getting scale off of glass shower doors?
Zep

Thanks, Zep, I'll see what chemical that is, and speak to Thetford.
Nick.

[nickcrowhurst]

LimeAway contains phosphoric acid as its active ingredient, according to the parent company website. Page F47 in my trailer's Airstream Manual lists the chemicals that will not harm the tanks and valves. Phosphoric acid is not listed, but a 10% solution of hydrochloric acid is listed. My elementary chemistry memories tell me this will dissolve limestone, producing carbon dioxide gas as a by-product. I'm hoping that will also help to clean the black tank indicators, which I suspect are partially covered in limescale.
Nick.

[JW84345]

Originally Posted by Zeppelinium

... I don't know about your particular installation, but in the Caravel and Overlander the valves were accessible without having to do anything with the tanks.
Zep

How did you get to the valve on the '70 Caraval? Your Overlander? Are they rear bath models? I have a '69 Overlander. I have no desire or time to get into a big project like removing the black tank. Maybe in the fall, but I have another 4 day trip to a MI State park (no hook ups) planned in two weeks.

Jim

[77airstream]

Are the dump valves on a center bath any different than on a rear bath? Where are they located? A slight problem I have is sometime in the past, my guess is, someone thought they needed to yank on the handles to free the valves, so the handles are no longer on the unit. Does anyone have any advice to give?

[vswingfield]

Originally Posted by 77airstream

Are the dump valves on a center bath any different than on a rear bath? Where are they located? A slight problem I have is sometime in the past, my guess is, someone thought they needed to yank on the handles to free the valves, so the handles are no longer on the unit. Does anyone have any advice to give?

Sounds like replacement rather than new seals for you. Thetford makes a drain valve lubricant. I use a little regularly. It also improves flushing out.

Best of luck,

Vaughan

[nickcrowhurst]

Originally Posted by 77airstream

Are the dump valves on a center bath any different than on a rear bath? Where are they located? A slight problem I have is sometime in the past, my guess is, someone thought they needed to yank on the handles to free the valves, so the handles are no longer on the unit. Does anyone have any advice to give?

The dump valves on my center bath are just forward of the streetside wheels. The valves come with just a short , perhaps 3 inch, handle, and extensions are screwed into these so that the ends of the handles are accessible outside the belly pan. You may just find that the extension pieces have come unscrewed and have dropped off. A flashlight down the access holes may reveal the situation. The extension handles were available from Thetford when I last checked.
Nick.

[ve3czn]

WARNING be sure that you have the Black Water Tank completely clean and flush with bleach several times. I was sucessfuly in cleaning my valves out by putting a pail under the outlet pipe then pouring about 4 quarts of water down into the holding tank, and then one quart of pool acid. ONLY ( ACID INTO THE WATER) leave for a couple of days ...or longer and see if the leak is gone You can tell if there is no water in the pail. It also works for the toilet seal.
Never I say NEVER put anything into the toilet like toilet paper no matter what the claim. We use a disposal container If there is some problem move the valve a few times to adjitate the joint Mine took 3 times and is still sealing......Better than the hard way. I had replaced mine and it was a WELL DO I HAVE TO EXPOUND ON IT>

Rae
Canada and Florida 22 ft Argosy

[77airstream]

Originally Posted by nickcrowhurst

The dump valves on my center bath are just forward of the streetside wheels. The valves come with just a short , perhaps 3 inch, handle, and extensions are screwed into these so that the ends of the handles are accessible outside the belly pan. You may just find that the extension pieces have come unscrewed and have dropped off. A flashlight down the access holes may reveal the situation. The extension handles were available from Thetford when I last checked.
Nick.

I wish that they just had dropped off! I talked to my a friend of mine last night, who I had let borrow the trailer last summer (part of the deal to let him borrow it was to fix a "unknown" valve problem). He told me that he took a panel out underneath to see if he could detect what was wrong, and what he came up with was the insides were rotted out. He said that he looked at a few dealers in the Tampa area and nobody had a valve of the size needed. What size is it? I've had several folks tell me that airstream has a "oddball" size valve, but I dont know personally. Is there any way I could buy just the "inside" parts and the handles?

[nickcrowhurst]

The Thetford valves and/or their repair kits are less easily available than some others, but they are high quality, and worth the extra expense, IMHO. If you google "thetford valve rv", you will find many places to buy the valves and/or repair kits, including here:
Save at RV Partscenter - RV Parts and Supply
There are a few variations in the type of valve and repair kit. You mainly need to see if your valves clamp-on to the tanks and waste pipes, or are glued on. By making a large enough access hatch to complete the repair, you can shine a flashlight on the existing valves, and read off the serial numbers embossed on the white plastic. The hardest part for me was cutting the access hole in the belly pan while lying in a field of fire ants. The entire job is nasty, and it's one Airstream job it would be REALLY good to pay someone else to do. (Especially if you aim to complete it in a morning, while full-timing, while your wife is at the store, as I did.)
Nick.

[77airstream]

Originally Posted by nickcrowhurst

The Thetford valves and/or their repair kits are less easily available than some others, but they are high quality, and worth the extra expense, IMHO. If you google "thetford valve rv", you will find many places to buy the valves and/or repair kits, including here:
Save at RV Partscenter - RV Parts and Supply
There are a few variations in the type of valve and repair kit. You mainly need to see if your valves clamp-on to the tanks and waste pipes, or are glued on. By making a large enough access hatch to complete the repair, you can shine a flashlight on the existing valves, and read off the serial numbers embossed on the white plastic. The hardest part for me was cutting the access hole in the belly pan while lying in a field of fire ants. The entire job is nasty, and it's one Airstream job it would be REALLY good to pay someone else to do. (Especially if you aim to complete it in a morning, while full-timing, while your wife is at the store, as I did.)
Nick.

Thanks, I'll check it out. I think you are right on paying someone else to do it. I can see that it could be a nasty job!!!