Small Leak From Black Tank Drain Plumbing? Or....?

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Lonestar Guy

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Texas
Hi all! Back from a trip to Red River NM. I'm fortunate enough to be on an acre and store my TT in my yard. When I get back from a trip I back it into the driveway for de-briefing, cleaning, repairs, whatever. After it sat there for some time, I noticed a wet spot underneath. I found there was slow drip from the underbelly protection where the black tank drain line comes through (see photos). I peeled back the underbelly a bit from the outside edge to see what I could see. Hard to see in there, but the only thing I can see 'wrong' is a loose clamp...(see photo) which I wonder if it was ever clamped. There is a lot of RTV around the joints. I have not removed the underbelly enough to see precisely where the leak is coming from but there is appears to be nothing dripping from above the connection point (that I can tell).

The odd thing is, the fluid doesn't seem to have a waste (nasty) smell to it. I did thoroughly rinse the black tank when dumping as we left the last site, but I wouldn't think it could THAT clean, as to not smell at all. Additionally, due to the undulations in the underbelly, I'm not thinking that fluid is running to the point from say the fresh water tank, but I could be wrong. Perhaps I'm stuck with peeling back more of the underbelly until I find the source. :(

Any thoughts to offer before I remove more of the underbelly? Thanks in advance!
 

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Rene T

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Does that clamp go around a rubber sleeve between two solid abs pipes?
If it does, it needs to be tightened. That’s problably where your leak is coming from.
 

Lonestar Guy

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Does that clamp go around a rubber sleeve between two solid abs pipes?
If it does, it needs to be tightened. That’s problably where your leak is coming from.
Well, I haven't exposed that much to see, due to the underbelly being in the way, but I guess I'm going to have to. Not sure why the clamp is that loose, unless the broke. Typically, a hose clamp won't open up that much on its own and it has never leaked till now.
 

Lonestar Guy

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OK, sure enough, as I suspected, the clamp is broken (photo), rusted first I guess from very minimal leakage then just plain broke, which has caused the dripping leak. The screw feature of the clamp was at the bottom, the perfect place to catch any leak so it would deteriorate sooner. :-/ Yea!

It seems that all the pieces are hard plastic...(photo) I see and feel no rubber tube, per Rene's thoughts. If so, this seems like a bad design as there is no allowance for flexing.

I am now wondering exactly where the clamp should go. It looks like the markings of a band where I have indicated with one red dot but it seems more likely it should be at the tank connection and it looks like that's where the original clamp was based on an earlier photo.

Can someone pls confirm the location for the clamp? Since it's not a rubber sleeve, I don't know how much difference it will make in any case but, as noted, I'm pretty sure it goes at the tank connection. If I seeing this correctly, it's just poor design and workmanship.

Thanks again!
 

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Rene T

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OK, sure enough, as I suspected, the clamp is broken (photo), rusted first I guess from very minimal leakage then just plain broke, which has caused the dripping leak. The screw feature of the clamp was at the bottom, the perfect place to catch any leak so it would deteriorate sooner. :-/ Yea!

It seems that all the pieces are hard plastic...(photo) I see and feel no rubber tube, per Rene's thoughts. If so, this seems like a bad design as there is no allowance for flexing.

I am now wondering exactly where the clamp should go. It looks like the markings of a band where I have indicated with one red dot but it seems more likely it should be at the tank connection and it looks like that's where the original clamp was based on an earlier photo.

Can someone pls confirm the location for the clamp? Since it's not a rubber sleeve, I don't know how much difference it will make in any case but, as noted, I'm pretty sure it goes at the tank connection. If I seeing this correctly, it's just poor design and workmanship.

Thanks again!
Put a new clamp back on at the same spot as the old clamp
 

Lonestar Guy

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Texas
Well, poot! The new clamp is on. I tightened it very tight. It still leaked! I tightened it some more and as I figured, as those clamps are prone to do if tightened too much, it slipped and probably broke a tooth... it wont I goobered up the clamp. You can only tighten those things so much before they slip and/or break a notch.

Anyway, I've got a shot that shows where it's dripping from and it, of course, seems to be at the joint of the tank collar and the adapter sleeve. I think I'm going to have to clean and epoxy/RTV that joint. RTV I guess as removing the epoxy in the future might cause damage.
^^^x2
All rubber hoses get the clamps in the same previous position, especially radiator hoses.
There are no rubber parts. All hard or molded plastic.
 

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donn

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Fernco fittings are relatively cheap. Go buy a new one. In case your not familiar with them, Fernco fittings is a rubber sleeve that slides over the two pipe ends and is clamped in place. Common plumbing device for connecting 2 sewer lines together.
 

Lonestar Guy

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Texas
Fernco fittings are relatively cheap. Go buy a new one. In case your not familiar with them, Fernco fittings is a rubber sleeve that slides over the two pipe ends and is clamped in place. Common plumbing device for connecting 2 sewer lines together.
Thanks, I was thinking about that option. I need to determine if the substance holding the hard plastic pieces together at this point is epoxy or RTV. If epoxy...bad, or I should say worse than RTV. Either way I'm not yet sure if I can separate the pieces without cutting them up and that could be an issue with the tank collar. I hate to 'settle' for alternatives but I may just settle for sealing as is with something. :-/
 

Aaron5er

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Sep 10, 2021
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Location
NE Georgia
Lonestar
I used this 3-M marine sealer if you determine that sealing as is after cleaning is your best option.
20210925_184844.jpg

I had a small crack at the lower outlet nipple made on my 80 gallon fresh water tank. Someone tried to seal it previously with what appeared to be a silicone based sealer which was easily peeled up from the edge with my fingernail.
I mentioned it to my son that works for a high end marina, he told me to hang tight and brought me this tube of sealer.
I had already drained the water, peeled off all the old stuff, wire brushed, dried with compressed air and cleaned up the area with acetone, per instructions.
I used an acid brush to build it up fan it out around the nipple, working fairly quickly because it skims over in just a few minutes.
24 hours cure time and I could not scrape or peel it up from the edges.
Gave it another 24 hours, filled the tank with no dripping and took it for a 30 miles pull.
Got home and it was not leaking.
Still holding good after 5-6 months.
That's some super stuff and he told me that they make some even better than this!
Let us know how it goes for you....
Aaron
 

BillB3857

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Jun 8, 2012
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210
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St. Louis Area
I had a similar problem. I went to the auto parts store and got a fiberglass repair kit. After cleaning it all up with acetone, I applied the fiberglass kit. It is still holding after 3 years. From what I was told, those fittings are "spin welded" which uses friction to melt the ABS while holding pressure on the mating surfaces.
 
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