Gray Tank Won’t Drain

[TKS323RL]

On our 2011 323RL the front gray tank drain T handle is next to the black tank drain T handle in the convenience center. Untill last week pulling this gray tank T handled caused the gray tank to open and drain normally. Today it does nothing. Pulling the T handled feels the same as it did before but nothing will drain out.

Has anyone else had this problem? How do I get to the actual gray tank drain valve to see if it's broken? Can I get to it going through the back wall of the storage area or do I have to pull apart the bottom?

[Logan X]

When I was new to RVing, my black tank sensor said the tank was at 3/4 full. I had dumped it recently but I trusted the sensor so I went to dump the tank. I pulled the dump handle and nothing came out. I thought I had a big problem until I realized the sensor was lying to me. The tank was empty but the sensor read 3/4 full.

All that to say, are you sure the tank has something in it? I just wanted to throw that out there as a possibility and to be a little self deprecating.

Good luck.

[tech740]

If what Logan said doesn't work, the tanks are usually lower than the storage compartment. You will have to drop the chloroplast bottom to access the area of the valve if I am not mistaken. Your storage compartment is on the floor level of the trailer, above the frame. Your tanks are usually between cross members of the trailer frame below the floor.

[KRumm]

My bet is something has clogged your tank piping... Say a sponge or something that got down the kitchen drain... Before you tear the belly apart try this... Close the black tank valve and open the grey... Then get a garden hose and and old towel... Stick the garden hose up the dump opening (twards the gery tank if possible) then take the old towel and wrap it around the hose and block the dump opening... Then turn the garden hose water on and try to back fill the grey tank... If this works be prepared for the grey tank water to come at you if anything gets dislodged - close the value... If it just seems to fill the tank than Logan is probably right... If it seems that you can't backfill the tank then the cable/valve may not be opening...

[JRTJH]

Originally Posted by KRumm

My bet is something has clogged your tank piping... Say a sponge or something that got down the kitchen drain... Before you tear the belly apart try this... Close the black tank valve and open the grey... Then get a garden hose and and old towel... Stick the garden hose up the dump opening (twards the gery tank if possible) then take the old towel and wrap it around the hose and block the dump opening... Then turn the garden hose water on and try to back fill the grey tank... If this works be prepared for the grey tank water to come at you if anything gets dislodged - close the value... If it just seems to fill the tank than Logan is probably right... If it seems that you can't backfill the tank then the cable/valve may not be opening...

An easier way to do this is to buy a $5 three inch "end cap with a hose adapter fitting", install that on the trailer sewer connection, connect a hose to the campground/home water faucet and the sewer cap, turn on the water and see if the pressure will "push the blockage" back toward the tank. Be careful as the tanks won't hold up under "excessive pressure" but the 1.5" and 3" are ABS pipe and usually rated at 125PSI or greater. The tanks and valves, however aren't rated that high.

After pressurizing the dump plumbing, all you need to do is "turn off the water faucet, crimp the hose, disconnect it from the faucet and allow it to drain through the hose and onto the ground/into the sewer system:

[66joej]

May need something like this to use a regular hose.
Female to female adapter.

[flybouy]

An old washing machine hose has a female on each end as well.

[travelin texans]

These suggestions is where I'd begin.
Its been stated on this & other forums that the problem was caused by the tank cut out when installing the drains/vents were let fall into the tanks where at some point have made their way to the drain.

[Park1911]

Be cautious backfilling your tank using that cap shown above. Excessive pressure could rupture your tank. Instead, dump 5-gallon bucket of water down the drain to see if it drains or if indeed the gauge is faulty and the tank is already empty. If it doesn't drain then the valve is broken or there is a blockage.

[TKS323RL]

Originally Posted by Park1911

Be cautious backfilling your tank using that cap shown above. Excessive pressure could rupture your tank. Instead, dump 5-gallon bucket of water down the drain to see if it drains or if indeed the gauge is faulty and the tank is already empty. If it doesn't drain then the valve is broken or there is a blockage.

After trouble shooting this drain problem it seems that the problem is the full sensors and maybe the drain valve for gray tank 2. It appears that the drain valve is always partially open so our shower and sink water always drain out and does not remain in the gray tank until you pull the T handle. Even if you close the T handle the water still comes out when the bathroom sink or shower is used.

Gray tank 1 for the kitchen still operates normally and can be used for flushing out the waste line after the black tank is empty.

I'll have to pull back the underbelly cover and see if I need to replace the valve for the #2 tank. I'm just glad it's not jamed closed.

[Roscommon48]

Caution. Using a campground/home hose to push water into your system is a way to cause bacteria into the WHOLE water system. YOU HAVE BLACK WATER WASTE IN THAT DRAIN PIPE. Do Not use a drinking water system the way it was stated above.

Why your water doesn't drain, you probably don't have any in the tank. Fill up the tank and try it, not the hose way.

[chunker]

Simple test for leaking valves is get a clear outlet for the waste tanks. Pour 1 gallon into the sink/toilet in question and see if you immediately get flow in the clear section. If you have the valve T handles closed and you see liquid, that waste valve is leaking. If no flow present, open valve to see it drain. Close before emptying that gallon and confirm no flow. Then empty. I keep a clear 45* section on the motorhome and use it to observe dumping and flushing.