Black water leaking into bulkhead

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Black water leaking into bulkhead

July 09, 2023, 09:32:23 pm

We just had the bulkhead (front and rear) repaired in Nacogdoches. We are now trying to track down a leak in the black water system. We think it was happening prior to the repair work and possibly as a result of the very cold temperatures this last winter. We emptied all of the tanks for testing and let it dry out (stop dripping). We did fill the gray water to 3/4 with a hose (to isolate the test - not connected to any water and fresh tank empty) and drained it with no apparent signs of leaking.

When we filled the black water with a hose, it filled up and starting leaking out of the bukhead. The tank meter only indicated 3/4 but we could see the clear water almost to the flange under the toilet. The tank meter never read full so we now know that is broken. Any thoughts on where to look for the leaking? Is there an overflow point?

Re: Black water leaking into bulkhead

Reply #1 – July 09, 2023, 09:39:55 pm

Look at the seal where the toilet drop goes into the tank and the tank vent seal also. When repairing the floor they may not have gotten the seal installed correctly as they are a pain to get right.

Mike

Re: Black water leaking into bulkhead

Reply #2 – July 09, 2023, 09:45:11 pm

Is that behind the panel in the same bay as the water pump (passenger side - just in front of the rear tires)?

Re: Black water leaking into bulkhead

Reply #3 – July 09, 2023, 09:48:01 pm

Depends on the bathroom lay out but on our coach Yes the commode is on the passengers side and the vent pipe is on the drivers side. Now if it was leaking before the floor was replaced then you may find a crack in the tank edge that will require welding up.

Mike

Re: Black water leaking into bulkhead

Reply #4 – July 09, 2023, 09:50:57 pm

Welding? Is the black tank plastic or metal?

Re: Black water leaking into bulkhead

Reply #5 – July 09, 2023, 09:57:08 pm

Some type of ABS I believe. With the right stuff it should be able to be welded up.

Mike

Re: Black water leaking into bulkhead

Reply #6 – July 09, 2023, 10:05:56 pm

Quote from: ViewRVs – July 09, 2023, 09:50:57 pm

Welding? Is the black tank plastic or metal?

Plastic. Based on the type of plastic you need a plastic welding rod that is comparable with the tank and a heat gun welder. Just across the way from our office is a guy that makes plastic water tanks for fire departments. He starts with flat sheets of plastic and welds them up.

Re: Black water leaking into bulkhead

Reply #7 – July 10, 2023, 12:06:58 pm

Fill it to 3/4 full using the dark tank flush hook up.
If it still leaks then you can rule out the toilet flange and the vent pipe as they are connected to the top of the tank.

If it's a slow leak and you are lucky..... it could be the dark tank dump valve leaking around the connector rod.

Re: Black water leaking into bulkhead

Reply #8 – July 10, 2023, 12:13:23 pm

Fred; I would open up the wall on the wet bay and do a visual of what is going on when you fill the tank to say 3/4. It could be leaking around the rubber connector that is coming of. the bottom of the black tank. If so, that is a fairly easy fix to remove and replace with new unless the clamp is loose and if that is the case, I would just tighten it up and check again. A bright light is your friend.

Re: Black water leaking into bulkhead

Reply #9 – July 10, 2023, 10:19:00 pm

Quote from: juicesqueezer – July 10, 2023, 12:13:23 pm

Fred; I would open up the wall on the wet bay and do a visual of what is going on ....

I know. That's a big job removing the wet bay wall with all of those things connected to it. They sure made it difficult.

My fear is that it is leaking at both the flange/vent at the top AND a slower leak at the valve.

Re: Black water leaking into bulkhead

Reply #10 – July 31, 2023, 06:45:09 pm

OK. We spent Saturday and Sunday tearing apart the wet bay!

We just had the front and rear bulkheads fixed in Nacogdoches and now we have water leaking from the bulkhead! (See photo) We don't want to ruin the work that was just done!

We do know that we have leaks at the gasket on the top of the black tank. When we filled/overfilled the tank, water bubbled up around the gasket and flooded the bay.

1. What sealant should we use to seal that?
2. Is the proper result of an overfilled black tank to have fluid in the toilet or is there supposed to be an overflow pipe?

We also believe that the faucet had a drip on the cold fitting. It was loose when we removed the connector. We are going to remove the faucet. It is a water source and we really didn't use it. There are are signs that the fittings on the grey polybutylene pipes might leak. We are going to replace as much of that as we can with new PEX tubing. With the faucet gone, there will be many less fittings to leak!

We also checked the Valterra dump valves. They don't leak when closed and hold fluid even under 3/4+ tank fill. They both DO have a slight leak when dumping. We plan to replace those but we'll need to find other posts for that!

Based on other posts, we also need to redirect the fresh water overfill to below the bulkhead!

We do plan to make a new panel design so that we can FREQUENTLY check there for any water/fluids! The goal/objective is to protect the rear bulkhead.

3. Are there any other sources of water in the bulkhead that we're missing?

Re: Black water leaking into bulkhead

Reply #11 – July 31, 2023, 08:51:55 pm

Quote from: ViewRVs – July 31, 2023, 06:45:09 pm

2. Is the proper result of an overfilled black tank to have fluid in the toilet or
2a. is there supposed to be an overflow pipe?

2. Yes
2a. No

Mike

Re: Black water leaking into bulkhead

Reply #12 – July 31, 2023, 09:07:03 pm

Quote from: Pamela & Mike – July 31, 2023, 08:51:55 pm

2. Yes
2a. No

Mike

Correct.

There is a vent through the roof.

Re: Black water leaking into bulkhead

Reply #13 – July 31, 2023, 09:19:34 pm

So what is the best way to fix that pipe and gasket into the top of the black tank?

After it is cleaned, would a silicone caulk or self-leveling sealer work?

Re: Black water leaking into bulkhead

Reply #14 – July 31, 2023, 09:44:59 pm

I would think silicone will seal against air escaping, but so sure it will hold against pressure of tank being overfilled since it will be on the outside. Don't know how much trouble to replace the rubber grommet

Re: Black water leaking into bulkhead

Reply #15 – July 31, 2023, 09:48:15 pm

Use some Goop marine sealant............ and try not to overfill the dark tank.
Amazon.com: Goop Marine Adhesive and Sealant Clear 3.7 Oz : Industrial &...

As an Amazon Associate Foretravel Owners' Forum earns from qualifying purchases.

Re: Black water leaking into bulkhead

Reply #16 – July 31, 2023, 09:52:04 pm

Yup, best way to not have the black tank overflow is to make sure you don't overfill it!

Re: Black water leaking into bulkhead

Reply #17 – July 31, 2023, 09:59:46 pm

Quote from: wolfe10 – July 31, 2023, 09:07:03 pm

There is a vent through the roof.

If it gets that high you would be in deep sheet.

Mike

Re: Black water leaking into bulkhead

Reply #18 – July 31, 2023, 10:27:44 pm

So you have a leak after you got the bulkhead repaired? Why didn't they address your leak at that time. The seal going into the black tank is replaceable once the toilet is removed. Pull the flange and reinstall new seal reinstall flange. Shower is gray water. Different chapter. New seal should work like the original for the next 25 years

Re: Black water leaking into bulkhead

Reply #19 – August 01, 2023, 09:23:08 am

Quote from: Pamela & Mike – July 31, 2023, 09:59:46 pm

If it gets that high you would be in deep sheet.

Mike

Agreed.

But, a blocked vent would allow pressure to build and contribute to leaks.

Re: Black water leaking into bulkhead

Reply #20 – August 07, 2023, 07:48:17 am

Black Tank Gasket - Completed
So I spent Saturday and Sunday getting the new gasket on the black tank and the flange put back down. I did need to bevel the end of the ABS pipe and use silicone grease to get it all to work. Yes, not overfilling the tank is a great idea!

Dump Valves
I did spend Sunday getting the valves off. Argh. Getting the bolts off of the valves was very difficult given the space. The access to the nuts on the back of the valves was nearly impossible. Here's my question.

Q) Is the intention to remove the entire piece of sewer piping, replace the valves while out, and replace the entire assembly into the tanks with the clamp?

If not, I can't be assured that the valves are tightened enough to prevent leaks.

Re: Black water leaking into bulkhead

Reply #21 – August 07, 2023, 09:34:32 am

Quote from: ViewRVs – August 07, 2023, 07:48:17 am

Q) Is the intention to remove the entire piece of sewer piping, replace the valves while out, and replace the entire assembly into the tanks with the clamp?

Unless any of the pipes are damaged, just clean up the valve mating surfaces and install the new valve.

Then look at opening up the fiberglass underbody to remove the water-soaked foam and dry out the metal.

Re: Black water leaking into bulkhead

Reply #22 – August 07, 2023, 10:06:27 am

Be careful to not over tighten the valve when installing the 4 bolts. It is possible to crack the housing as well. They don't take much torque to tighten properly. When I replaced the valves I got it all dried out, put dry paper towels under anywhere that might leak, and then ran water into the black and gray tanks and let it hold for a day or two to check for leaks before closing up.

Since you mentioned not reinstalling the faucet, or keeping it disconnected, you may want to cap it at the manifold valves. You would not want to inadvertently turn on a valve even if capped in the wet bay. I think we have used the faucet once. I keep it turned off at the manifold.

Re: Black water leaking into bulkhead

Reply #23 – August 07, 2023, 10:43:14 am

I hadn't thought about turning it off at the manifold, good idea. I use the faucet frequently to fill a bucket to get the bugs off the windshield and hook a hose up to it to rinse it off

Re: Black water leaking into bulkhead

Reply #24 – August 07, 2023, 09:32:31 pm

So, I also discussed this with Chad at Foretravel tech support. He advised against removing the pipes from the tanks. He did say that he inserts the bolts from the back and has the nuts on the front to make it easier. He also uses a thin board to slightly raise up the pipes for better access. He indicated that he's done a bunch of these and it's not an easy task with the limited space.

This week I'll try to install the new valves and keep the vocabulary as family friendly as possible.

I am blessed with a DW that thinks very highly of me and is very encouraging and supportive! She's got more confidence in me than I do!

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