Black Tank Valve Replacement

[Bill_Diana]

It seems every 2 years I need to replace the valve on the black tank because it become very difficult to pull. What am I doing wrong that causes this to happen?

[Harvey51]

I had the annoying small leak that made removing the drain cap a messy job.
I followed advice from this forum to put a tablespoon of vegetable oil in the toilet and sink after every tank dump. No more leaks!

[Bill_Diana]

obviously this issue is more common than one might believe. Also, seems like lots of solutions tried by many of us. Again, thanks for all the comments.

[Gjac]

I had the same issue with my black tank valve. I added a grease fitting on top of both valves 10 years ago. I only greased the gray valve twice but grease the black valve 5 times in 10 years to keep them operating smoothly. The last thing you want to happen is to pull the T handle out of the plastic threads in the valve because it is so hard to open.

[fourthclassC]

Howdy, I thought I'd share my experience here. I had some leakage by the valve which made taking the cap off unpleasant. I changed the seals. seals only. This did not leak for about a year. Then it started leaking again. Just a little. So I think the blade itself is scored up from sand in the tank at some point. I think that if I change the entire valve (not just the seals) it will stop and last a long while without leakage/seepage.

[Lynnmor]

Not sure that vegetable oil is a good idea. I made cutting tools for a food processing plant and thought it would be a good idea to coat them with vegetable oil and stack them in a package. When the company went to use them, I got a phone call saying they couldn't pry them apart. The entire stack needed to be boiled.

A big issue with the drain valves is that the poor design has an opening into the rectangular portion where the is when open, and c**p goes in there. Just another cheap, poorly designed RV component.

[Rvpapa]

One way that works for us that I do about once every couple of months.
Dump tank; dump a five gallon bucket of water through toilet, close dump valve and pour in about a pint of cheap vegetable cooking oil (canola) and then wait a few minutes to let the oil float on the surface of the water that remains. Next go out and work the valve open and closed as rapidly as you can. Valve gate will pick up enough oil after five or six open and closes to make a surprising difference. Works for us for a good twenty years so far.
Art.

[MDKMDK]

Buna-N is another name for nitrile rubber.
https://www.applerubber.com/hot-topics-for-engineers/understanding-the-composition-of-a-nitrile-buna...

[RLS7201]

The seals in your waste tank valves are NOT RUBBER they are Buna-N. I install grease zerks on my valves years ago with NO SWELLING. I use the same grease that I lubricate my chassis with and the valves still work like new.

Richard

[Bill_Diana]

Thanks folks for you input, ideas and suggestions. I'll use a combination of all that you have said.

[MDKMDK]

How do you store the RV? Valves open or closed? After I dump and rinse the tanks before storage for any length of time, I close the valves and add a liberal dose of RV antifreeze, in the gray and black tanks, so that the valves and seals will be lubricated while the RV is sitting. It's the propylene glycol in the A/F that keeps the seals lubed. I've used it for over a decade with no problems. Valves will stick with lack of use, but once you pull/dump them a couple of times, they usually free up.

[LadyRVer]

I spray the rod on pull handle with silicone spray every couple of months. Makes a big difference.

[ernie1]

I had a similar problem repeatedly until I found out that as I would change the seals or sometimes the entire valves, I would lube the seals and surfaces with vaseline or plumbers grease. This was recommended by the manufacturers and people on various sites. This was the problem: petroleum products will degrade rubber type products making them soft and spongy. In my case, the seals were swelling and would cause it to drag as the valves were being used. Now I only use silicone products like plumbers grease that is SILICONE based and not petroleum based. Have not had trouble for years since.

[MDKMDK]

Try reducing fibre in diet, and increase Omega 3 fish/krill oil.

[2oldman]

I'm not sure, so I direct you to a few youtube posts.