Momentum 348m - Water behind Nautilus P1

[rob_mo348]

New m348 owner here, thanks all for participating in this awesome community!

Somehow I got some kind of leak in the basement of my 348m.
I retightened the connections on my Nautilus P1, and after checking everything, the leak appeared to have stopped.
I then tested the bathroom sink and noticed a drip coming from the center of the faucet, I tried retightening but that didn't fix it.
That's fine, for now I'll just not use that sink.

The kitchen sink has no leaks either, so that's good, same with toilet and shower. All good.

The issue that I am having trouble with is somehow I got about 1-2mm of water inside the hole cut behind the nautilus.
I have no idea how to drain this water, is there a trick or should I use a towel?

Thanks in advanced!

[dneisner]

Rob,

Grand Design has chosen to use re-enforced vinyl hose with pex in their RV's. The problem with the flexible vinyl is that it should be connected to a hose barb fitting. Grand Design has not done this on their coaches. I just spent over $300 in tools and fittings to correct this issue in my 2019 5er. I have owned three other campers before the Grand Design. I have always done my own winterization and have never had a single problem over the past 13 years. This year i did my normal open up procedure. After flushing the system and doing my sanitization of the fresh water system i looked under my coach. I saw water dripping from the low point drains and tightened them up. That is when water dripped from the chloroplast on the top of my hand. after removing the screws from the plumbing chase I was welcomed by an absolute mess of wires, cables, and plumbing lines. The only answers for what I found was a lack of pride in the work or simply the result of a "slap em together" approach to the construction process. After clearing a way to the leaking lines I found the flexible vinyl hose dripping at a tee fitting for both the hot and cold lines. After repairing them I began the process of correctly building the P1 water system. I researched the P1 system on the internet they called for PEX tube to be used to make the connections. Grand Design chose not to do this and used a mix of vinyl and PEX. I have completely rebuilt the system and now hope that it all holds up. I still have a few vinyl lines that I will work on after I am sure that the problems I have had are all corrected and no new problems are found.

BEFORE

AFTER

[dneisner]

having problems with adding another photo. here is the after

[boyscout]

New m348 owner here, thanks all for participating in this awesome community! Somehow I got some kind of leak in the basement of my 348m. I retightened the connections on my Nautilus P1, and after checking everything, the leak appeared to have stopped. I then tested the bathroom sink and noticed a drip coming from the center of the faucet, I tried retightening but that didn't fix it. That's fine, for now I'll just not use that sink. The kitchen sink has no leaks either, so that's good, same with toilet and shower. All good. The issue that I am having trouble with is somehow I got about 1-2mm of water inside the hole cut behind the nautilus. I have no idea how to drain this water, is there a trick or should I use a towel? Thanks in advanced!

Hi Rob, welcome to the forum.

That "inside the hole cut behind the nautilus", if you mean the subject of the second photo you published, is the top of your black tank. It has the input on the left and the vent on the right.

The problem with finding water there is that it can come from almost anywhere in the plumbing above, around, and in that hole. I had a problem more than two years ago with a Reflection 320MKS - captured in a thread here - that led to a sagging water-filled underbelly and 1/4" to 1/2" of clean water on top of the tank. None of I, other very experience folks here, or the dealer could explain it. It happened, I cleaned it all up and checked exhaustively for weeks, the dealer checked it, and it didn't recur before we traded the trailer months later.

So from that experience, here are suggestions from the experience including some suggested at the time by others.

- probably not the fitting on the conduit from the toilet or the vent - you'd likely smell something if the leaks are from there.

- possibly (remote IMO) water running down the outside of the vent pipe from the roof, i.e. a leak in the roof around the vent.

- as @dneisner has suggested, any of the connections to soft braided hose back there, especially hot water connections. Water from any of these will fall on the floor, but can often easily drain from there down the hole and onto the top of your black tank. Only way to find these issues is to connect to a system with good water pressure and lie in the basement wiggling stuff around while someone else uses the fixtures inside the trailer. Whether or not a leak is found, as suggested put replacement of that soft hose on your to-do list.

- all other connections, especially those on the back of the Nautilus and on the water pump. Again, best way to find them is by being there under full pressure and while fixtures are being used.

- put some water in the fresh tank and use pump pressure while again testing fixtures and connections.

- consider the basement door(s) during wet weather / driving.

So, I dunno if it's worth anything to you to get suggestions from the guy who failed to find the source of his own trouble, but I hope it helps.

Good luck.

[geotex1]

Here's a trick if you cannot find the source of the water - buy a can of PAM Baking spray, which has the flour mixed into it and available at any grocery store. Spray anything your suspect could be the source to leave the film of flour and then run your plumbing and anything leaking will leave an obvious trail. If the idea of wiping the cooking oil off is no bueno, you can get aerosol leak detection powders - Wurth and Forch are two producers, which are completely dry powder once the propellant flashes off. After you find your leak, your can remove the powder with vacuum/dusting or air blowgun. You'll likely need to order in the latter options from the internet.

[rob_mo348]

Thanks for the ideas. This is all hugely helpful. I have a feeling the water leak is related to the pump, although the water inside the hole is still a mystery to me. I am buying a shop vac however, and hopefully that will help me keep it all under control.

Thanks for the useful knowledge, when I figure this out I will post here.

[rob_mo348]

I have replaced the bathroom faucet, perhaps that will fix this issue.

[geotex1]

I have replaced the bathroom faucet, perhaps that will fix this issue.

Do try to report back to close the loop. It can be helpful for other owners that are troubleshooting similar.

Good luck!