Black Tank Valve Leak

Topic: Black Tank Valve Leak (Read 1197 times) previous topic - next topic

Black Tank Valve Leak

March 30, 2019, 09:37:14 am

My coach stinks!

I replaced the black tank valve with a new identical replacement, a 3 inch Valterra Bladex valve. It now has a slow leak (one drop of poop water per minute) as follows:

- As the black tank filled with poop water, the valve gasket started leaking
- Various torque values have been used: Very tight, tight and looser. Cross-tightening sequence.
- Good quality silicon grease RS 494-124 was lightly applied to all rubber seals. I did not apply the grease to all crevasses.
- It takes a lot of force to separate the flanges and insert the new valve with it's two gaskets.
Could one gasket surface not be seated correctl?
- The gaskets are facing the correct direction. E.g. O-Ring-like surface facing the blade.

My questions are:
1. Should I buy a special grease for the non-moving interface (gasket to flange), like Danco Waterproof Grease?
This grease is thicker, not meant for moveable surfaces. The thinner grease would lubricate the gasket's movable blade-facing side and the flange side would get the thicker Danco grease.

2. Replace the valve again, but goop on much more silicon grease and moderately torque the bolts?
I have a spare valve kit.

3. Re-seat the valve by dumping the tanks, removing the bolts, and wiggling the valve?

4. Let it leak and put up with the smell until I get home in two weeks? Fix it at home where I have access to more tools, a poop bucket, and don't have campground rules and neighbors to worry about?

I am at Sun-n-Fun and fortunately have access to dump and fill at the campground. Heaven help me if I dump poop water on the ground.

Re: Black Tank Valve Leak

Reply #1 – March 30, 2019, 09:54:47 am

Tim to remove the valve without a mess. Dump and rinse your tanks, then tilt the coach to the P/S and give things a bit to drain. Remove and make sure things are clean and make sure all flange surfaces are flat. Reinstall following the instructions. If memory serves me those bolts don't get real tight. Remember tights tight too tight is broken. Also look closely make sure you don't have a cracked flange.

Re: Black Tank Valve Leak

Reply #2 – March 30, 2019, 10:01:30 am

I had a similar issue when we first bought our coach. Took the dump valve apart and found a small piece of bone from somewhere that kept the valve from seating all the way. Just enough for about a drop per minute.
Cleaned out the bottom between the seal lips of the bone.
Reassembled the valve and problem was worse!!
Turns out the seal on one side was folded into where the blade was supposed to go.
THAT DID IT!!!!!
I put a clear elbow and a third valve on the end of the dump line until we got home where I could do a better and more thorough job without getting in deep "doo doo" with anyone. As a precaution I still keep the clear elbow and 3rd valve on the line.
I realize our dump setup may be different than yours and you may not be able to leave the elbow and valve on all the time, but you might consider a termination cap with the male hose fitting on it as a temp stop gap measure. A pair of gloves and a pail when you are ready to do a dump. Pail under the hose fitting, remove the hose cap (this is where the gloves come in handy) and let the liquid that passed your Valterra valve out. Then remove your termination cap and hook up your "stinky" hose.

Re: Black Tank Valve Leak

Reply #3 – March 30, 2019, 10:02:42 am

Yup, what Bruce said.
What comes after too tight? Too loose!! (broke)

Re: Black Tank Valve Leak

Reply #4 – March 30, 2019, 10:15:05 am

Tim, if i remember correctly, there is a sequence for the bolts, like back in forth on all corners and snug in the end. Those O rings can curl on you when you insert the valve between the two pipes, as it is tight. Like others have mentioned, check both ends of the pipe for any debris.

Re: Black Tank Valve Leak

Reply #5 – March 30, 2019, 10:35:40 am

Thanks for the quick replies. I must have tightened the bolts TOO TIGHTLY in a diagonal pattern because the plastic flange started to curve. Loosening the torque made the flanges straight again. I'll try to check for cracks and will put my iPhone in there and take detailed photos.

I'll go buy that thicker Danco Waterproof Grease at the Home Despot just in case I decide to "dive in", eh'hem, and resolve the problem.

I am making a Youtube video about this and will publish it after the leak is resolved.

Re: Black Tank Valve Leak

Reply #6 – March 30, 2019, 10:45:36 am

Tim... I'm in the process of installing new valves and would like to see your video! I too had some leakage when I first installed them (new valves and gaskets). I used plumber's silicon for a lubricant (consistency of honey).

George

Re: Black Tank Valve Leak

Reply #7 – March 30, 2019, 10:47:25 am

Yes, very likely a gasket not seating correctly.

The silicone grease is just fine.

Reassemble taking special care that the side gaskets are properly seated.

Would buy new gaskets, assuming you will likely find one damaged.

These are rubber gaskets-- they do not require a lot of torque. Over torquing will distort the valve housing and make the blade bind.

Re: Black Tank Valve Leak

Reply #8 – March 30, 2019, 10:58:35 am

A frequent cause of leaks is that the ORings get out of place and pinched when tightening the valve bolts. No amount of tightening will fix it. Empty the tanks. Tip the coach to the pass side as suggested. Disassemble and put in a new valve body as long as it is all apart. It makes no sense to try to reuse a damaged seal.

This is the one if you have remote handles.
Amazon.com: Valterra T1003PBC 3" Valve Body: Automotive

You can get a new blade seal gasket kit. I have not found a new oRing kit.
Amazon.com: Valterra T1003-9VP Bladex 3" Valve Seal with Hardware, (Set of...

Use lots of plumber's silicone grease in the oring grooves to hold the oring in place. Add more to the blade and blade seals. Get the valve body in place and rotate back and forth to make sure it gets seated. Don't over tighen the bolts. There is no torque spec but these are not engine bolts.

While in there slip a shallow aluminum foil baking pan under the valve. It will contain any future leaks. Once it is all back together put some paper towel under the valve and do a 12 hr leak test. Something colored in the tank will help. I dumped in some left over RV antifreeze and water, easy to see.

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Re: Black Tank Valve Leak

Reply #9 – March 30, 2019, 11:19:59 am

Option #3............Git-R-Dun

Re: Black Tank Valve Leak

Reply #10 – March 30, 2019, 01:00:29 pm

Sooner or later, the valves leak. One of the best things I've done is install that 3rd valve which gives me some peace of mind. It is better to find that you have a leak on the other valves when you open that third valve, as opposed to taking the cap off!

Re: Black Tank Valve Leak

Reply #11 – March 30, 2019, 04:08:10 pm

What Sven said....3rd valve. Second line of defense for both black and grey tank valves. And, ability to shift grey to black if needed to gain grey capacity when dry camping.

Re: Black Tank Valve Leak

Reply #12 – March 30, 2019, 07:29:09 pm

One other thing is that those valves are installed wrong as the manufacturers state the valve should be set at a maximum of no less than 30° off level. In other words the handle/valve should not be parallel to floor as yours show. This will allow water to fow into valve stem area if seal is not sealing right.
JohnH

Re: Black Tank Valve Leak

Reply #13 – March 30, 2019, 09:33:43 pm

Third valves are great but if the valve body itself is leaking the third valve won't help. A pinched ORing (between the flange and the valve body) will leak whether you have a third valve or not.

Recent third dump valve installations (split from another topic)

Re: Black Tank Valve Leak

Reply #14 – March 30, 2019, 10:16:38 pm

Quote from: John Haygarth – March 30, 2019, 07:29:09 pm

One other thing is that those valves are installed wrong as the manufacturers state the valve should be set at a maximum of no less than 30° off level. In other words the handle/valve should not be parallel to floor as yours show.

Umm....somebody at the factory must not have gotten the memo on that...both of my OEM dump valves were mounted horizontal. That's the way it was when we bought the coach, and that's the way I replaced them when I did my 3rd valve mod.

No leaks or problems working valves in 5 years. Knock wood. See my old post linked below for photos.

Third Waste Gate Valve

Re: Black Tank Valve Leak

Reply #15 – March 30, 2019, 11:01:56 pm

Quote from: John Haygarth – March 30, 2019, 07:29:09 pm

One other thing is that those valves are installed wrong as the manufacturers state the valve should be set at a maximum of no less than 30° off level. In other words the handle/valve should not be parallel to floor as yours show. This will allow water to fow into calve stem area if seal is not sealing right.
JohnH

Water will flow there as it is under head pressure even if vertical, less valve guide to get fouled in vertical.

Re: Black Tank Valve Leak

Reply #16 – March 31, 2019, 11:20:56 am

Fixed it:
See photos:

1. Sawed off the pipe so the valve could be assembled and installed properly.
The old (new) gaskets were folded over. Dang!

2. Installed a 3 inch rubber coupler.

3. Greased gasket, valve body, all crevasse and pipes fittings with silicon grease. It was greased better than a greased pig.

4. Easily mated gaskets, valves and pipes. Tightened with light torque.

If it leaks, I'll eat my hat.

Video to follow.

Re: Black Tank Valve Leak

Reply #17 – March 31, 2019, 11:26:40 am

Quote from: Chuck & Jeannie – March 30, 2019, 10:16:38 pm

Umm....somebody at the factory must not have gotten the memo on that...both of my OEM dump valves were mounted horizontal. That's the way it was when we bought the coach, and that's the way I replaced them when I did my 3rd valve mod.

No leaks or problems working valves in 5 years. Knock wood. See my old post linked below for photos.

Third Waste Gate Valve

As I stated your seals/valve faces are obviously good if you have not had any leaks even given the direction of gate, so that is fine.
Maybe different scenerio if a fault in valve seal.
I know when I replaced my manual valves with electric ones a couple of years ago, it also said about the angle of fixture, but of course that is more important with the gear etc mechanism in these compared to simple ones that where installed by factory.
JohnH

Re: Black Tank Valve Leak

Reply #18 – March 31, 2019, 04:16:56 pm

Me thinks that with the pressure of a full tank above the valve, a bad stem seal is going to leak regardless of its orientation.

Re: Black Tank Valve Leak

Reply #19 – April 01, 2019, 10:28:22 am

See my Youtube video at Tim's RV Tips #12, "Pooper", Replace Black Tank Valve, April 1, 2019 - YouTube

It shows an improved process to cut the OEM pipe and re-fit the valve for a leak-free seal.

Re: Black Tank Valve Leak

Reply #20 – April 01, 2019, 10:38:42 am

Quote from: bbeane – March 31, 2019, 04:16:56 pm

Me thinks that with the pressure of a full tank above the valve, a bad stem seal is going to leak regardless of its orientation.

Maybe the stem seal never sees liquid until the valve is opened. Just a thought.

Re: Black Tank Valve Leak

Reply #21 – April 01, 2019, 11:25:55 am

Quote from: craneman – April 01, 2019, 10:38:42 am

Maybe the stem seal never sees liquid until the valve is opened. Just a thought.

There isn't any "stem seal" on the rod that pulls the valve gate open. There is only a molded plastic guide in the top of the valve housing. The plastic guide is not meant to be water tight. I posted a link (in another thread) to a Airstream forum thread where the OP cut the top off a Valterra dump valve. The operating rod goes through the plastic guide, and then connects to a slot in the top of the sliding "gate". This connection slot is located outside of the round rubber seals on both sides of the sliding gate. If any waste water gets past the round rubber gate seals, it could run freely out of the top of the valve.

AFAIK, the orientation of the valve - horizontal or vertical or whatever - would have no bearing on this type of rubber seal leak.

See the link below for excellent photos of the gate valve construction:

Waste valve handle and rod pulled out of the valve - Airstream Forums

Re: Black Tank Valve Leak

Reply #22 – April 01, 2019, 11:42:02 am

Thanks for the link Chuck. Good info for when a bad day comes.

Re: Black Tank Valve Leak

Reply #23 – April 04, 2019, 01:21:18 pm

I was going to say that coating the valve stem with silicon grease would be a good idea. However, perhaps after moving the valve several times to coat the valve guide, the valve stem should be wiped to may eliminate the problem of dust contamination.

Eventually, poop water will leak past the valve stem guide, but proper maintenance will help extend it's life.

Re: Black Tank Valve Leak

Reply #24 – April 04, 2019, 01:25:26 pm

Tim,

I don't see dust contamination as an issue, as the valve is closed (stem inside the valve) except when dumping.

And, if permanently set up and gray valve open (which we don't do), wiping off the stem before closing would be easy.

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