Black tank odor and leak

slaytop

Well-known member
I noticed an odor in the storage compartment for a couple of years that seemed to come from the black water tank but I couldn't see any sign of a leak. Once, while winterizing, I pushed some compressed air through the flushing port to clear the hose of water and I smelled the foul odor again in the compartment. I thought that the air would escape up the roof vent and I shouldn't smell it.

This year I added a support under the black tank to keep it from excessive sagging. To test the support I filled the tank with water and it leaked from the top out of sight. Normally when you fill the tank to capacity it will push the excess fluid into the vent system and plumbing above the tank. If it is sealed properly it shouldn't leak. I wasn't sure if it was a crack, puncture from a screw or leaky plumbing.

Since I couldn't see where the leak was coming from I removed the black tank and tested it out of the trailer. The leak was coming from the vent stack where it screwed into the top of the tank. The putty on the threads of the 1 1/2" adaptor screwed into the tank top was not sealing properly and allowed a small amount of water and air to pass through.

I'm in the process now to reseal the tank using new adaptors and teflon paste before reinstalling it.

Because of this experience, I would suggest that people empty the black water tanks before they are completely filled to capacity (or risk some unexpected leaking).
 

newbie

Northern Virginia
Glad you were able to figure out the problem. When you disconnected the tank, how did you separate the tank from the drain?

John
 

slaytop

Well-known member
I'm doing some major work on my unit right now. The bellies are off and the storage floor is out for replacement. The partition behind the storage area is also off with the aluminum frame still in place. I was able to reach the toilet drain pipe through the partition frame. It's also possible to reach it from the side by removing the battery compartment. Since I modified the dock earlier I was able to access the vent pipe through the dock compartment. It's possible to reach it through the storage partition but more difficult. To get the black tank out I had to remove gray tank #2 and its supports. I cut the toilet drain pipe and the vent pipe above the holes in the panel they came through above the tank. I disconnected the drain valve and cut the flushing hose. I cut the forward tank brace at each end just outside of the tank length and left a stub at each end to bolt on a new piece. I did that rather than try to remove the original bolts which were nearly impossible to wrench out. The tank dropped forward and out with some help. When replacing I will reconstruct part of the plumbing to match up with the original and put in a new piece of bracing. I may make the final pipe connections with flexible collars and clamps. This is not an easy job.

If I had known the exact nature of the leak from the beginning, it's conceivable that I could have removed and resealed the vent pipe from the top without taking the tank out. I hope I get all this work done before the Nashville rally.
 

newbie

Northern Virginia
Wow, that is a big job. I for one would love to see some pictures as you go.

When you reinstall the tank, do you think it would be/is possible to install it so it leans towards the 3" drain side? At 3 or 4 percent?

Good luck,
John
 

newbie

Northern Virginia
After thinking about it , I sure wish they made these tanks with sloped bottoms. Like a grain or coal car on a train. Would make things work a lot better.

John
 
The waste tank bottoms have a slope toward the corner of the drain. The tops are level. They are shallowest at the point furthest from the drain. The shallow end of the black tank is where the toilet drains and is one reason why some people experience rapid build up of solids that seems to block normal use. It is best to support this tank design with level braces to use the full capacity. If the tank sags, and it will when full, hope that the bottom will return to its normal position as it is emptied and the weight of the contents is reduced.
 

Larryheadhunter

X-Rookies Still Luving it
While you at it, you might want to get one of those spinning cyclone at Camping World that swirls around and sucks out any foul odors. Worked for me.
Never smell tank odors again!
Even a gentle breeze rotates the Cyclone 360° to follow the wind. It creates a powerful vortex that pulls odors up and away so they don't enter your RV living area. Low profile design. Attaches to any plumbing vent with no drilling into rooftop.
 

JohnDar

Prolifically Gabby Member
I was looking those some time ago. Looked interesting, but now that you don't smell it do the neighbors sit under their awning with clothespins on their noses when the wind blows? Curious, albeit warped, minds want to know.

To be honest, though, I've not had any odor intrusion back into the rig from the tank vents. Who knows, maybe the MaxxAir covers on the fans blocks it from getting sucked in. Or maybe I'm just a hoity-toity whose stuff don't stink :D
 

newbie

Northern Virginia
You tanks are still vented to the roof. I don't think your neighbors are going to smell any more stink because of a little vent/wind thingy on the vent. (Not to diminish the effectiveness of the vent/wind thingy, I am sure that it serves it purpose preventing a back draft up through the toilet.)

John
 

slaytop

Well-known member
Since my last post I have repaired the black tank and reinstalled it. I will post a few photos of the process and the tank. #2374 photo shows the cut drain lines and a stub of the original brace that held the tank. #2377 shows the cut vent stack behind the dock compartment and the hole where the original plumbing came through. I actually cut the vent pipe twice, flush with the floor and then a few inches higher. #2383 shows the shallow end of the tank where the toilet drains in. The plastic disc leaning against the new pipe was found stuck inside the tank and is the same size as the drain opening. #2386 shows the shape of the tank. Notice how the bottom slopes toward the drain from the other side and the end. #2387 shows a new brace that will attach to the stubs of the old brace. The old brace is welded to a 1 1/2" x 1/8" new angle iron using plug welds. The old brace will fit between the stubs giving a uniform surface as the new brace is bolted to the old. #2398 shows the same area as #2377 with the new brace in place and the new plumbing connected with a rubber coupler.

I determined to take out the tank by cutting only one brace. That may not be possible in all units and it was a tight fit in mine because the new pipe stubs needed to be fitted on the top to see them poke through the holes over the tank. There's a lot to this project left unstated and hopefully none else will have to do this.

I hope the photos help.
 

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