Thetford Tecma not holding water

[BVThunder]

I previously contacted Thetford about my Tecma not holding water. They said to verify that the hose from the stool had a "J" loop that was above the water line. The stool was pulled and the loop was verified. The hose clamps were tightened. When we started on our winter trip, the stool was functioning normally. Now, it is no longer holding water. It very slowly drains out over about an hour. I am out of factory warranty by one month. Got any suggestion?

[Jim T.]

Originally Posted by BVThunder

I previously contacted Thetford about my Tecma not holding water. They said to verify that the hose from the stool had a "J" loop that was above the water line. The stool was pulled and the loop was verified. The hose clamps were tightened. When we started on our winter trip, the stool was functioning normally. Now, it is no longer holding water. It very slowly drains out over about an hour. I am out of factory warranty by one month. Got any suggestion?

If you contacted Thetford during your warranty period and you are now having the SAME problem, perhaps recontacting Thetford is the first thing you should do. They MAY extend your warranty & fix your problem.

[DAN L]

Both under, pita spell checker!
Use an old toothbrush and scrub the "ball valve" surface where it seals and the seal also. A small amount of Tp or other waste will cause the leak that you describe.

[BVThunder]

Originally Posted by DAN L

Both under, pita spell checker!
Use an old toothbrush and scrub the "ball valve" surface where it seals and the seal also. A small amount of Tp or other waste will cause the leak that you describe.

Not that kind of stool. It is a macerator/electric stool.

[aiken rver]

Originally Posted by BVThunder

Not that kind of stool. It is a macerator/electric stool.

The problem is caused by Winnebago not putting a vent on the drain. When you flush the toilet it creates a vacuum which will then slowly pull all the water out of the bowl until the vacuum is broken. I got all of the stories about the pipe being to low, the bend in the drain not being high enough, etc. Lived with it for months. Then I bought an Oatey 39017 Sure-Vent Air Admittance Valve with 1-1/2-Inch by 2-Inch PVC Adapter and installed it directly behind the toilet. It just barely fits and probably should be a little higher but works great. Now the toilet hods water exactly as it should. Winnebago has vents on every other fixture but not this one which needs it the most! We really do like this toilet know.

Hope this helps you.

[BVThunder]

Originally Posted by aiken rver

The problem is caused by Winnebago not putting a vent on the drain. When you flush the toilet it creates a vacuum which will then slowly pull all the water out of the bowl until the vacuum is broken. I got all of the stories about the pipe being to low, the bend in the drain not being high enough, etc. Lived with it for months. Then I bought an Oatey 39017 Sure-Vent Air Admittance Valve with 1-1/2-Inch by 2-Inch PVC Adapter and installed it directly behind the toilet. It just barely fits and probably should be a little higher but works great. Now the toilet hods water exactly as it should. Winnebago has vents on every other fixture but not this one which needs it the most! We really do like this toilet know.

Hope this helps you.

Makes sense to me. Sounds like the fix I need.

[Lv2Roam2]

OK guys - pictures, if possible, would be invaluable. I've moved these toilets away from the wall - I don't see a lot of room for extra stuff. Thanks ...

[aiken rver]

I forgot to take pictures but am working on some instructions on how to do the mod. Should have them later tonight.

[aiken rver]

As nearly as I can remember here are the steps to add a vent to the Tecma toilet. I did this almost a year ago so I may have not remembered exactly. It has worked perfectly since this mod.

Basically I just placed a wye in the drain line and added an air admittance (one way vent) to the drain. I think I attached pictures of the parts used. I was just having so much fun that I forgot to take pictures as I did it.

Parts list:

1 PVC DWV 1 1/2" wye
1 PVC DWV Street Elbow 45 Degrees
1 piece of PVC pipe 1 1/2" about 3' long
1 Oatey 39016 Sure-Vent Air Admittance Valve with 1-1/2-Inch by 2-Inch PVC Adapter, 2-Inch
1 Flexible PVC Coupling Fitting 1 1/2"
PVC Glue

Remove the 4 screws holding the toilet to the floor and slide the toilet away to gain access.
Pry the wood top off in order to have better access to the area.
Loosen the clamp screw holding the toilet rubber drain to the black PVC drain pipe and disconnect the rubber drain.
Hold the existing drain up against the floor as far as possible and cut the verticle part of the pipe just below the floor (I used a Sawzal). You want to be sure to have enough pipe sticking up to slide a PVC flexible rubber coupling onto the pipe. Before you slide the coupling onto the drain pipe, cut a pvc pipe to fit into the coupling and the wye fitting. This pipe should be just long enough to provide a solid fit into the 2 mating fittings with just maybe 1/2" of extra pipe. You want to be sure it is firmly attached but not sticking up any higher than needed. Once this is cut, slide it into the coupling and then slide the coupling onto the existing drain pipe. Now tighten the screws on the coupling (which probably are facing the wrong way to reach).

Slide the wye fitting onto the pipe sticking up (do not glue yet). Cut a piece of pipe long enough to fit onto the straight through part of the wye and hold the vent just below the wood top. The vent should be as high as possible but not hitting the wood top when you remount the wood.

Place a 45 degree street elbow into the remaining wye opening and turn it so it is pointing so you can attach the toilet rubber drain. Cut a piece of PVC pipe to fit the elbow and allow a surface to connect the rubber toilet drain to.

Once you are sure everything fits glue all of the fittings together and allow to dry for a few minutes. Do a couple of test flushes and look for any leaks.

Slide the toilet back into position and replace the 4 screws.

I did not reattach the wooden cover but just set it in place. It has never come off and I can check that everything is OK.

[aiken rver]

I managed to get a few pix of the mod. One thing I saw is that I ended up not using the street elbow but just a short piece of pipe to connect the Tecma rubber drain hose.

[BVThunder]

Originally Posted by aiken rver

I managed to get a few pix of the mod. One thing I saw is that I ended up not using the street elbow but just a short piece of pipe to connect the Tecma rubber drain hose.

Thanks! Tech is coming tomorrow. I'll show him both options.

[BVThunder]

Thanks to George (aiken rver) we are now holding water in the Thetford Tecma. The tech that showed up to install the fix was knowledgeable about the issue. He had previously preformed the fix on a number of Winnebagos. According to him, Winnebago is the only manufacturer not to vent this type of stool or black tank. When the black tank is empty or near empty the stool will hold water. As it fills up, a vacuum forms that sucks the water out of the stool. When the tank is almost full you can stand there and watch the water level drop. Winnebago will not admit to an issue. However, they will pay under warranty to install the vent including parts less the cost of the service call.

The fix takes a little less than an hour:

1. Remove four screws holding stool to floor.
2. Pry off wood top to compartment behind stool.
3. Disconnect stool outlet hose from stand pipe.
4. Cut off about 7" from stand pipe.
5. Fit wye to stand pipe.
6. Cut two approximately 2 1/4" sections of 1 1/2" ABS pipe.
7. Put one section in each of the remaining outlets of the wye.
8. Fit 45 degree elbow to side of wye.
9. Cut approximately 5" of 1 1/2" ABS pipe and fit to other end of elbow.
10. Fit Oatey vent at other end of 5" pipe.
11. Check for assembly fit.
12. Disassemble and glue.
13. Attach flexible coupling between existing stand pipe and new assembly.
14. Attach stool outlet hose to top of wye.
15. Test for leaks.
16. Reattach wood top.
17. Replace 4 screws to attach stool to floor.
18. Use and enjoy!

[aiken rver]

Glad the fix worked. Not sure I agree with the tech's assessment though. My black tank is vented. When trying to figure out my problem I also blocked my other toilet open thinking maybe the black tank vent was blocked, but to no avail. Didn't know Winnebago would pay for the parts.

Anyway, glad it works.

[BVThunder]

Wanted to let you know that Winnebago stepped up to the plate and authorized payment for parts and labor less the $45 service call. They balked at first saying that this was an unauthorized modification to their engineered plumbing system, and there was no space for the vent we installed.

They requested photographs. I informed them that both the tech and I had independently verified that the J loop was in place as per Thetford specs. I explained that as the tech told me there was no rhyme or reason for the Thetford not to hold water. This just happened on some units. I think they must have been impressed with the engineering of the fix and squeezing the vent into the space. I hope the next person looking for a fix will find this thread.

This forum and others have saved my bacon not to mention how many dollars over the years. Special thanks to aiken rver.