Black Tank DRAMA

[214skier]

Hi, me again. In the season of chronic RV trouble… at four year mark…maybe we should have traded it.

Latest— Black tank full. Cant get it to dump. First reaction was clog— i have tried:

- Tons of solid dissolving chemicals.
- Run the black tank flush until the water level reaches toilet valve.
- Used a 6’ piece of 1/2 flex pipe to physically try to dislodge any blocks (from my view here it seems like all the solids are now fully liquid).
- Bought a cap I could drive a ton of water up the pipe back to the black tank (no resolution).

Other symptoms

The dump valves have been slowly deteriorating to the point neither of the grey tank valves will close (the push rods are pretty corroded given the fact they are exposed to the road).

Up until recently the black has opened and closed with ease. Pulling and pushing the rod meets some resistance…but no where close to the resistance in the grey tank valves.

My crurrenty hypothesis is the black tank valve is frozen closed—I dont know what to do.

Should i, cut into the corrugate to look at the black tank valve? If so, can I manually open it?

[Carl n Susan]

Yes you can manually open the valve if you have access. Either drop the coroplast (easy enough to and my 1st choice) or cut a 3-sided flap in it. You will be able to access the valve, the cable attached to it and can manually open the valve (vice grips make it easy). You may have to undo the cable connection first though.

[214skier]

Originally Posted by Carl n Susan

Yes you can manually open the valve if you have access. Either drop the coroplast (easy enough to and my 1st choice) or cut a 3-sided flap in it. You will be able to access the valve, the cable attached to it and can manually open the valve (vice grips make it easy). You may have to undo the cable connection first though.

I cut through the coroplast to verify the black tank valve is “open” (disappointed by this fact).

So I must have the mother of all clogs.

Given my grey tanks are stuck “open”…i think I will cut into coroplast to find both of those valves. Close them manually then use the back flush system to hopefully push through the clog that must have entirely sealed the exit.

Open to any and all advice *thank you much in advance.*

[AZ Traveler]

Find a professional tank cleaner such as KleenTank.

[Daryles]

I changed the black tank valve seals recently. Not a hard job with the tank empty and dried out.
To do this on a full tank you would need to pump out the tank via the toilet.
When I did the seals, the first time I didn't get them in the groove correctly and it leaked. When I took it apart the second time and reassembled it I slathered the seals with plumbers grease (silicone grease) and the valve blade and the pipe ends. I got the seals in and seated correctly and it has been perfect since.
While I was in there I added lubrication holes to the valves.
THIS WORKS!!!
I can open and close all my valves with one finger.
As Carl mentioned above, dropping the coroplast isn't hard. Putting it back up is awkward.

Valve lubrication making lube holes for silicon grease

https://m.youtube.com/watch?v=TGv9THpOdmw

[214skier]

Originally Posted by Daryles

I changed the black tank valve seals recently. Not a hard job with the tank empty and dried out.
To do this on a full tank you would need to pump out the tank via the toilet.
When I did the seals, the first time I didn't get them in the groove correctly and it leaked. When I took it apart the second time and reassembled it I slathered the seals with plumbers grease (silicone grease) and the valve blade and the pipe ends. I got the seals in and seated correctly and it has been perfect since.
While I was in there I added lubrication holes to the valves.
THIS WORKS!!!
I can open and close all my valves with one finger.
As Carl mentioned above, dropping the coroplast isn't hard. Putting it back up is awkward.

Valve lubrication making lube holes for silicon grease

This is brilliant. What if the valve is under coroplast?

[Daryles]

Yeah, you have to drop the back three feet of coroplast on the forward drop down to reach the grey 1 (bathroom) and black tank valves.
For the grey 2 (kitchen) you need to drop the front three feet of the back (main floor) coroplast.
For future access you can cut the coroplast and insulation while you have it down so your cuts are accurate.
Honestly after you have it down the first time, and put it back up with screws it's easy to take it down and up. The first time down use a pry bar under the washer and a 1/4" socket on a drill in reverse to remove the nails.
Putting up use 1" #12 self drilling bolts through the nail holes. The self drilling bolts will go through the frame without holes but you have to push really hard.

[214skier]

Thank you much for the advice. I will try to get to lubricating the dump valves today as you suggested.

I have Tank Kleen this morning, hoping to have this resolved!

[Daryles]

I have Tank Kleen this morning, hoping to have this resolved![/QUOTE]

Let us know how it goes.

[214skier]

Tank Kleen came to me and worked miracles. Cleared the clog, water blasted the interior of black and both grey tanks. Back flushed to thoroughly rinse all three tanks. They cleaned my hot water heater (who knew?...I suspect all of you). Awesome service--so very thankful. Will use them again.

I have mobile RV repair coming to fix all three valves plus lubricate. Hopefully this will be behind us.

[AZ Traveler]

To prevent further black tank issues, only open the black tank valve when actually dumping. Keep it closed until the tank is over half full.

After dumping and flushing the tank put at least 10 gal of water in before using it. Lots of water is the secret to preventing the poop pyramid which is the cause of most clogs.

[214skier]

Originally Posted by AZ Traveler

To prevent further black tank issues, only open the black tank valve when actually dumping. Keep it closed until the tank is over half full.

After dumping and flushing the tank put at least 10 gal of water in before using it. Lots of water is the secret to preventing the poop pyramid which is the cause of most clogs.

Great advice. Thank you