clooged sink

It is possible your under sink air vent is blocked. Possibly a plastic bag got tossed over it. That would prevent the water from flowing. Poo

Moved from Forum Technical Support

Thanks Old-Biscuit. The grey tank is empty. All other water sources, shower, other sinks, are draining fine. I've looked over the plumbing diagrams from Winnebago and they show no Galley Tank. I have unclogged many drains in my lifetime in my homes but this one has me baffled.

schlep1967 wrote:
It is possible your under sink air vent is blocked. Possibly a plastic bag got tossed over it. That would prevent the water from flowing. Poo

X2, possibly the vent on the roof has been blocked by something. If water flows with the "P" trap out and not with it in it seems that it would be a vent problem. JMO

Is it a slow drain or a full backup and nothing drains? When it was draining did it ever gurgle or burp as it drained?

Snake it again but this time have someone close by the gray tank and listen for the snake bottoming out in the tank. 6' should have you in the tank, but verify just to be sure. If the snake is at the tank and the line is clear as you suspect then you might have a situation with the under sink air vent and draining is creating a vacuum.

Look under the sink for one of THESE or something similar. It's going to all the way in the back of the cabinet up behind the sink. Just follow the drain line to the Tee and go up. It should be just slipped into the drain pipe and not glued so you can remove it and test the drain. There should be one for all the drains. Vanity, shower, clothes washer and such. Anyplace there's a trap will have the vent close by. You won't find many of these in older domestic plumbing systems due to the multiple roof vents that were used in the past. RV's they are pretty common with the actual roof vent is to vent the tank and not the individual interior drains.

Good luck.

I would say that it's a blocked air admittance valve under that sink. When you look at the plumbing for the sink, do you see a section of pipe which runs upwards with something that looks like a screw on cap? That's the air admittance valve. When you send water down the drain, this valve opens to allow air into the plumbing to allow the water to flow down freely. If it's plugged, the result is what looks like a plugged sink. It will only effect that fixture, the rest of the system will drain normally.

If you have one of these, unscrew it and see if the sink drains normally. If it does, you found your problem.

Of course, that assumes there is no separate galley tank. :)

~Rick

P.S. On edit: Dale.Traveling beat me to the post. His picture is of one type of valve, but you should be able to pick up a different type for under $10, perhaps under $5. Here is the one used on our RV.

Also, you can download the plumbing (and other diagrams) from Winnebago here.

P.P.S. I just downloaded the plumbing diagrams for a 2012 Journey 40U. You do have an air admittance valve on that sink. I only see one gray tank and one black tank shown in the plumbing diagram. Those diagrams are AWESOME! Nice touch, Winnebago! :)

Just a quick thought here.. Is your sink on a slide out? IF so, you might check for a kink in the drain hose. The drain must be flexible so it can move with the slide. One of my friends had this problem on his coach and he found a kink in the drain hose.

As long as I have been on RV.net, I've never heard of anyone ever mention a separate galley holding tank. And the valve for it in a different place? Wow, seems inconvenient to have it plumbed that way.

MM.

Mr.Mark wrote:
As long as I have been on RV.net, I've never heard of anyone ever mention a separate galley holding tank. And the valve for it in a different place? Wow, seems inconvenient to have it plumbed that way.

MM.

My trailer has a separate galley tank. Yes a separate drain fitting about 2' away from the black/grey. The inconvenience to drain is minor compared to the convenience of addition capacity.

My trailer has rear kitchen with galley tank behind axle. There is another gray tank in front of axle and then black tank in front of that. All 3 are plumbed to drain in front of axle. I think quality control was on vacation when mine was built because the shower and bath sink were plumbed to black tank and nothing to the gray. Dealer corrected this.