Tub not draining

[Daveputt]

Well I am back moving from 1 problem to another.
I purchased an 86 HR Imperial with P37 chassis. Going thru everything for the first time and trying to learn all the RV systems since I've never done this before.
Today's issue is the tub not draining. It appears that both sinks are filling the tub. Toilet flushed and dump valve works. The gray tank didn't dump anything.
I looked down the vent from the roof and I can see it's not blocked down to the elbow. I lightly used a plunger but it didn't do anything and I didn't want to get too aggressive. The rv is winterized and still has antifreeze in the lines.
My gray water tank is on passenger side with kitchen sink (above tank). The tub and bath sink are on drivers side. Why would the kitchen sink go to opposite side then back to tank? My sensors say its empty but who knows if they are working correctly. My tanks also have rigid foam sprayed all over the connections so I don't know if I can take it apart without major demo.
What's my next step? Snake?

[vsheetz]

Over full gray tank usually reveals itself by placing water in the tub/shower. Double check the tank is really empty. Else blockage somewhere redirecting water to the tub/shower. I have good success with the gel Drano.

[Daveputt]

How do I check? If the sensor is bad, is there a manual way to check? Mine is sprayed with insulation.

[BFlinn181]

Is you gray tank dump valve a direct 'hands on' pull or are you connected by a cable to the actual valve? You obviously have water in the tank from running it down sinks and in tub, so you should see water when valve is opened. You'll need to make sure the gate valve is actually moving when you pull the handle. If it's a cable pull, try to pull the actual gate open with vice grips or whatever to dump tank. Then remove and replace the gate valve and the pull cable if equipped. The valve itself is only held together with 4 bolts.

[homeless]

I find that is I use the stopper in the tub for showers it gives the drain a chance to push hair down with more volume of water with just one time drawn. Am I talking English?

[Daveputt]

Originally Posted by BFlinn181

Is you gray tank dump valve a direct 'hands on' pull or are you connected by a cable to the actual valve?

It looks similar to this...

I will take a look inside if possible to check if the gate is opening. It was a lot harder to pull than the black water valve.

[BFlinn181]

Sorry about the bad spelling. You could try some silicone spray on the rod, but it might have pulled loose of the actual plastic gate slide. Since the tank is probably full (water backing up into tub) that adds pressure to the valve and makes opening it harder. If you drain the tank and the valve is still stiff, you can replace the gaskets and use plumber's lube (silicone grease) on the valve gate and to help hold the gaskets in place as you reassemble the valve.

On many RVs, the grey tank valve is smaller than the black tank valve, make sure you get the right size.

[Daveputt]

Just checked the valve and I can see it IS opening when I pull. Just purchased a snake, will start gently, hopefully that gets it.

[BFlinn181]

Unless you can see up the pipe and see the actual gate opening, how do you know it's opening? The metal rod can move but be detached from the gate. If your snake hits an obstruction at the distance up the drain to the gate, it's still not moving. If you push a plastic shower curtain up under the valve, you could unscrew the valve body, let water drain away on the plastic and rebuild or replace the valve.

[Daveputt]

I can see it opening. It's only a few inches away from the 90

[BFlinn181]

O.K., gently probe with the snake. Hope you're wearing old clothes!

[Daveputt]

I'm afraid!!! Not sure how old the water is in the tanks! I remodeled an old house and dealt with old gray water in the pipes and it still sends shivers!!

[Daveputt]

Used a 20' snake from the dump side and extended it all the way out. Went from tub, couldn't fit it down the drain without forcing it so I went thru the vent under bathroom sink. It's only a few inches downstream from tub. Went all 20' and nothing.
Went to kitchen sink and same thing.
Went up on roof and went down vent on tub side...nothing.
Went to the other vent on passenger side, not sure where this one goes to. Snake went down drain extremely quickly and popped out of handle and down the drain where it now sits. Gone to bed frustrated. This shouldn't be that difficult, I'm quite handy around the house I promise

[Daveputt]

Starting to feel a little silly. After a few hours of troubleshooting I realized the tub does drain fine. It won't drain the last few inches when the rv is parked on a slight down hill. I didn't think it was much of a slope but when looking how the tub drains, it all makes sense now.
Now I am off to my next item on the list! Hopefully I will be a little more efficient!