Fixing leaky black water tank

[Popga]

Time to swallow my pride and hopefully prevent others from my mistake. While emptying my black water tank, I decided to close the drain valve and fill the tank almost full to flush it out. Well....while filling, I started chasing butterflies and forgot to turn off the water. Boom! my trailer rocked and starting leaking yucky water out from coroplast. My gallon counter read only 1 gallon too much, but the was enough. There was also a backup of water into the toilet bowl. While trying to troubleshoot, I had a friend man the hose shut off while I watched into the open toilet bowl for the tank to fill. As soon as the water got close, I had him turn off water. I had lowered coroplast enough to see the black water tank. Water started running down the side of the black water tank, originating from the top of the tank. I obviously blew either a seal or the tank.
I went to the dealer and was told its going to be 4 months wait to get in and then if I need a new tank, who knows how much longer.
Since I'm pretty handy (even if not very smart), I thought I'd attempt to drop the tank myself and just order a new one. Any advise on how to drop the tank??? By my figuring, there's a vent, a connection to toilet, a connection for flushing and an electrical connection for tank heater. All advise would be greatly appreciated.

Erik

[Jlawles2]

Erik, You may be able to pull the toilet and inspect if it's a straight drop in to the tank to save dropping the coroplast. IIRC there was a write up where someone had a Tech come out and do just that.

I find it hard to believe you would have cracked or split the tank since it's vented to the roof.

[howson]

Cate&Rob -- have you seen this thread? Not sure if you've actually done a tank replacement or not.

Popga -- from book knowledge (not practical experience), the "gotcha" will be when you have to cut out the hole for the vent, toilet, and spin in the sensors. The tank will not have any of these pre-configured (at least that's what I learned at school). This is not an easy task. Be prepared, no matter how much you drain and try to get the tank and lines empty, to get "liquid" leftovers showering down as you take stuff apart.

Jlawles2 -- it's very possible. I did almost the exact same thing and split the washer tank on my 315RLTS. Overfilled it and BOOM! water everywhere. I know it's a split in the top because I can still use the tank without any issues (no leaks)--but if I try to fill it up out comes the water. So what the OP described I'm afraid is exactly what happened. The seams on the tanks are not very robust, so they gave before the water could be pushed up the vent stack and out the trailer. I don't know how to do the math, but it must be considerable pressure to push water the height of a trailer roof through a 1.5" pipe. (I can visualize all the engineers here reaching for their reference books and calculators...)

Howard

[Cate&Rob]

Popga
Hi Erik,

We are going to have to engage the TT guys on this forum to understand how to get eyes on the top of the tank. (In my 5th wheel, I can see these connections in the pass through storage area under the bathroom) I am hoping that you "blew a gasket" . . . specifically the grommet around either the pipe from the toilet to the tank or the grommet around the vent stack. You are going to have to figure out how to access these pipes and grommets to install a new tank . . . so, might as well figure this out first and do an inspection before dropping the tank.

Rob

[Popga]

howson

Update....
Thanks for the responses. The top of the tank is completely unavailable for inspection without removing coroplast. Once I had cut a section away. I could stick my head just far enough into the belly to inspect the top of the tank. Unfortunately, there was an approximately 9" split about 1 inch from the edge of the tank. I ended up pulling the tank and due to the area of the split, I do not think it is fixable. Man is that a flimsy tank....I will write an update of steps in the removal and replacement when done and I have my wits about me.
But I will say now, That my former trailer was an Arctic Fox, and its tank stood up well to me being the owner. I never had any issues of overfilling, and the water just overflowed the top of the vent. I believe JLawles2 to be correct in the assessment that this POS tank can't withstand the pressure built by the vent filling and bursts before it overflows from the vent. I take full blame and responsibility, but....seems like there are issues that need addressing, like using a quality tank in the build. I know I will be searching for one and hope to find it.

BTW Howard, I'm not sure how to include or flag multiple folk, Like Rob and Joseph in my reply....

Thanks,
Erik

[howson]

Popga -- looking forward to reading the write-up. You may be the first to do (at least that I know of) so there will be a lot to glean from what you learned.

[uwskier]

Check for a plugged vent while you're at it. It seems crazy to me the tank wouldn't be able to withstand the pressure buildup of filling up the vent pipe unless the pipe was completely obstructed somehow.

[Cate&Rob]

Check for a plugged vent while you're at it. It seems crazy to me the tank wouldn't be able to withstand the pressure buildup of filling up the vent pipe unless the pipe was completely obstructed somehow.

You would not be able to fill a tank with a blocked vent. If the air can't get out, the liquid won't go in. There are many RV stories of black tank contents coming out the roof vent . . . so, I agree, splitting the tank seems like an unusual failure mode.

Rob

[Jlawles2]

howson Howard, google geek out b/c I can't remember the equation but I can do it on my calculator with the conversion function.

But according to google: Each foot of elevation change is equal to 0.433 PSI of water pressure. Think of a vertical column of water. For simplicity, 8' of vent pipe is less than 4 psi. Size of pipe does not affect water pressure (static of course).

[howson]

Jlawles2 ...so there I was, enjoying a nice nip of Jameson while listening to Sarah Jarosz on iTunes and reading the forum...and then I read your post.

[Jlawles2]

howson if we ever meet up, we will have to partake in adult beverages and discuss the "BOX" you spoke of. You may even need to introduce me to this Mr. Jameson.

[Popga]

howson
Glad my troubles can bring y'all together!
And save me a thimble full....


Erik