Dump Valve

Sneakinup · 01-13-2004, 02:27 PM

As I gradually get through testing all my onboard systems, I find little items in need of attention. Well, not really little items.

While testing my blackwater tank for leaks, I noticed that I am getting a steady drip out of the dump port. The tank is not leaking anywhere else. I filled it completely with water and continuosly checked under neath. (The PO's were nice enough not to leave me any presents in the tank.)

I know the Dump Valve is leaking slowly, and I have never opened it before.

How big a deal is it to repair/rebuild this valve? I have the bathroom taken apart and have pretty good access to the valve. Does anyone know what is involved? Rebuild kit? A good cleaning? Please tell me I don't have to drop the tank!

72 Overlander.

Thanks!

pepper48 · 01-13-2004, 02:42 PM

I had the same problem and tried some of the things I learned on this forum. I first drained the tank and used a coat hanger bent into an "L". I ground the short end of the "L" round and carefully cleaned out the valve seat. You need to be careful you don't cause damage to the seat because you will then definitely need to drop the pan or cut an access to replace the valve. After I cleaned out the seat I made sure I kept something in the tank to keep the seat lubricated. This approach worked for me.

thenewkid64 · 01-13-2004, 06:05 PM

The halves of the valve are held together with 8-12 screws. If you separate the halves you can replace the seal without having to cut into the pipes. If you have good access now is the time to do it. Although I have had dried out ones leak and after some use they seem to seal back up. Use is the best thing for these types of valves.

Sneakinup · 01-27-2004, 03:41 PM

I've filled, emptied (the tank was bone dry by the PO... fortunately) and refilled the black tank a dozen times in hopes of the valve refreshing itself and hopefully holding. It still drips consistently. The blade does not seem to go all the way down either, as I have to really force the clasp down. I have the toilet out and tried to get to it with a wire hanger, but it didn't seem to do anything.

I have access to both sides of the valve, but those screws look tough to get to. I'm guessing that an offset screwdriver would be the trick. The valve is a Thetford T-1169 Model 01447. Based on the pic, does it look like I can disassemble it without a major catastrophe?

thenewkid64 · 01-27-2004, 05:53 PM

Sneak,

If I remember right that valve goes into a pipe that runs through the bumper storage compartment, right?

If so you may want to look at how much disassembly is necessary to get to the unit form the bottom too. There is sometimes a screw directly on the bottom

You should be able to separate the halves of the valve far enough to replace the seals only. I did the one on our 76 MH and what I saw was the old seal had gotten folded into the slot so the blade would not close completely and also would not seal. The seal kit will work for a few models of valve, so do not be concerned when you have parts left over.

Sneakinup · 01-27-2004, 06:01 PM

[quote]If I remember right that valve goes into a pipe that runs through the bumper storage compartment, right?

Yes, it goes directly in to the bumper area where the grey water attaches in behind it. I'll have to get out there and really dig in. I am pretty confident that there is crud blocking the blade from going all the way down, or like you said, the gasket may have folded over. From what I have read, the worst case scenario with me attempting to clean it out is to end up needing new seals.

There are two big screws facing the bumper, and a bunch of smaller ones facing in to the trailer. I saw on one of the RV supply sites that Thetford sells and offset screwdriver to get to them.

Until it warms up (sounds funny being that I am in Florida) I decided to add 5 gallons of water to the tank with some mild soap in the hopes that it will dissolve some of the gunk. If that doesn't work, then I will begin the disassembly process.

thenewkid64 · 01-27-2004, 07:09 PM

If you are going to soak it I would suggest that you leave the valve in the open position with the sewer outlet capped so the slot can be wet and maybe soften up the guck. It may take more than 5 gallons. You could also try a hose up the outlet with the valve open and a brass spray nozzle in a wide spray pattern.

TomW · 02-15-2004, 10:44 AM

Sneakinup,

Testing assemblies on my ’67 Overlander yesterday in preparation for reassembly, I found my dump valve (the exact one you have) is leaking. Now I’m lucky that my black tank is sitting on the workbench, so I can get to everything easily. After disassembling everything to get to the valve, I came to the conclusion that, on my model, it would be impossible to remove the valve without first dropping the tank unless you were willing to butcher the galvanized box to gain the necessary clearance

I have attached a picture of what appears to be the cause of the leak. Unfortunately, I am a poor photographer with an inexpensive camera, so I have to add 999 words to the picture: The inset picture is supposed to highlight where the seal “unfolded”. In cross-section, think of the seal as a “U” shape. The gate, around 20 years ago, snagged one leg of the “U” folding it flat. Now, 20 years later, it has retained that shape:

TomW · 02-15-2004, 10:52 AM

Oops, picture was too big; Here's a lower resolution:

Sneakinup · 02-28-2004, 03:54 PM

I managed to get the dump valve off of the tank without having to remove the BW tank. Upon closer inspection I found that brown trout had died in the middle of the seal, hardened, and created a damn that only salmon could jump! With the use of a small mirror and a flashlight, I could see that the seal was not folded over or out of its seat, and that there was just death and decay holding the valve from resting in its assigned slot. Using a few throw away tools, I managed to get them to swim down stream and out of the clutches of the gate valve.

I then temporarily attached the valve back on to the tank and poured some "valve lubricant and rejuvenator" in to the empty tank and added 4-5 gallons of fresh water. It appears that my problems in that department may be solved as the "dripping" has ceased!

I want to thank Brett (Thenewkid64) for encouraging me to try to get this valve working before I attempted to do the dirty deed of trying to replace it. I feared that if I did have to replace it, I might one day be ready for the 2006 Sarasota rally... perhaps WITH my trailer this time!

TomW · 03-05-2004, 06:53 AM

I dont't know if Thetford still makes the SLIDE EZ VALVE REPAIR PACKAGE part number 03827-S, but I was able to find one at an RV place that used to be an Airstream dealer.

Before I found it, I was about to to convert the valve to an all plastic unit, because I thought it was my only option.

I thought I would post a picture of the kits for anyone keyword searching on Thetford 01447 Slide-ez valve.

Tom

Rick Alston · 09-07-2004, 11:32 AM

Tom

To remove the useless valve, I had to cut off the four corner screws of the valve because they were totally rusted; and that left me with four rusted posts that go into the fixed plastic holder that is attached to the BW tank. I have tried unsuccessfully to unscrew them with a vise grips and they don't budge. Is there a metal sleeve in the plastic holder for the screws or is each screw imbedded directly in the plastic?

One more question: if I ruin the plastic holder during my attempt to remove the screws, how do I remove it from the bottom neck of the BW tank without destroying the tank? I think it is glued in place.

Rick

TomW · 09-07-2004, 01:54 PM

Quote:

Originally Posted by Rick Alston

...Is there a metal sleeve in the plastic holder for the screws or is each screw imbedded directly in the plastic?

...if I ruin the plastic holder during my attempt to remove the screws, how do I remove it from the bottom neck of the BW tank without destroying the tank? I think it is glued in place.

On my tank, there were no metal inserts in the flange - the screws screwed into plastic. My bottom two screws were rusted away, so I understand your situation. I did, however, manage to remove them with vicegrips.

I think you will be able to get your screws' remains out okay. On my tank, the flange is solvent welded in place, and would have had to be cut off to install a new one. If that had happened, I would have ordered the new flange before cutting the old one off.

Hope this helps,
Tom

Rick Alston · 09-07-2004, 02:04 PM

Tom

Thanks for the reply-I am glad that the screws are directly imbedded in the plastic flange. Since the screws aren't coming out with vise grips, I think I will heat them (being careful to not directly heat and melt the plastic) to loosen the plastic enough to wiggle out the screw remains. I did this process with the tail light lens' and it worked great.

Rick