2023 MHC 381 TB kitchen sink

[Bovibear5280]

I have a 2023 Keystone Montana high country 381tb it is not my first RV, nor is it my only one. Everything seems to function the way you would expect it to with the exception of the kitchen sink. Every time I’ve used this thing the kitchen sink clogs below the P-trap and below the couch itself somewhere between the floor of the kitchen and the underbelly underneath there’s got to be a valve going into the gray tank. I’ve taken it into the shop for warranty. They say they fix it, invariably it fails and I bring it back. They say they fix it again and it still is not working.

I’ve run a snake through and there isn’t a clog

I’ve checked the utopia turbo vent and removed it and it does function though I am getting a replacement to see if that’s the problem. However, when I took it off, it ended up flooding my kitchen so I don’t think that’s the problem.

It’s currently only had water running in it and we’ve been very diligent not to run any food items down it

Once it clogs, it appears to drip slowly into the undercarriage beneath the kitchen floor collect water there and I’ve ended up popping a hole in the underlayment just to allow it to drain so it doesn’t stink.

I’m at my wits and here trying to figure out how to get this problem solved which is why I’m coming to Reddit

Is there a valve between the kitchen and the gray tank that could somehow be clogged or jammed?

Any advice would be welcome

 

[Mikendebbie]

I searched the forum using “slow draining sink” and several threads come up on the subject. The most common suggestion is that your air admittance valve under the sink is defective or needs adjustment.

I installed new kitchen cabinets and sink in our S&B a few years ago. The plumbing in my mobile home is similar to the plumbing in the Montana. The new sink drained VERY slow until I adjusted the (new) air admittance valve - problem fixed! I had installed it down too tight (because I did not know what I was doing!). YouTube improved my plumbing skills - and I loosened or raised the valve higher…and now the sink drains like a pro installed it.

 

[Bovibear5280]

Thank you for the recommendation however, I’ve actually taken the air admittance valve off and it still has the problem. In fact when I take the air bit off, it overflows into the pipe that I took it off of it’s got to be something wrong with the plumbing at this point, I just don’t know what

 

[Mikendebbie]

Take a photo of your sink plumbing and post it to this thread.

 

[LeftOverParts]

Maybe try a borescope that you can connect to your phone, a laptop, or one that has the screen already attached.

Just a camera and LEDs on a long cable are about $35 on Amazon. They don’t seem to last too long but have found them to be helpful to look inside walls and tight spots around a an engine.

Besides the clog, if still under warranty, your dealer should fix the leak too.

 

[RMcNeal]

First, there should not be any kind of valve in the drain. If you can run a snake down the drain, it should bottom out in the galley gray tank. Are you sure your galley gray tank is empty? There have been a few on the forum that were never told they have 2 gray tanks so they didn't empty the second one.
Second, there should also be a vent on the galley tank itself. Could it be clogged? That could cause it to not drain as the air in the tank can't escape. I have read about critters getting down the vent stack on the roof and blocking it.