Black Water Valve Won't Close

Most DW's have small hands and she should be able to reach up there and clear any obstruction. :B

Some coaches have a flush valve that shoots water directly in to the black tank to break up debris. If your coach has that feature, try that first since the water pressure will be greater. While this is going on, open and close the black tank valve to help dislodge the obstruction.

Not completely closing is a whole lot better than not opening which is what one normally reads. Suspect the seal might have come loose and is jamming the gate or as you wrote something from the tank is keeping it open. TP is pretty mushy once wet so probably something a bit harder. Loose a toothbrush or hair comb recently? It a good flush as you wrote doesn't solve the problem removing the valve is probably your only option. Pretty easy once your tank is empty. Four bolts and it's out. If you want to make this really easy just replace it.

You'll need to be hooked up to sewer for this to work, but I've had luck doing it. Pull the black handle so all the junk is gone. Then run a hose into the toilet and down the pipe and turn it on full. Wait about one minute then rapidly open and close the valve 6-10 times. Leave the valve open to drain the tank with the hose still running. Repeat as needed until the handle goes all the way in.

I put on a third valve over the outlet. Then I can close it and use the grey tank to back flush. It is a heavy stream of water and it will dislodge stuff very easily.

Had a similar problem a while ago. I let the tank empty, then poured in PineSol and a few gallons of hot water. Waited a bit, then used a hose to direct pressure up into the drain valve. It cleared the paper mass that and formed a plug. Worked for me.

Certainly try all the suggestions previously posted, but if it is still not closing all the way as what happened to me, try the following procedure.

Using your jacks tilt the coach towards the blank tank drain valve. Drain and flush the tank numerous times. Then tilt the coach in the opposite direction. Put on a pair of rubber/latex gloves and disassemble the tank valve and clean the groove where the tank valve seats.

We had a similar problem a few years ago, caused as it turns out by a piece of costume jewelry. If none of the trick above work and you decide there is no recourse to disassembling the valve, a post we made from our problem may be of help:

Repairing a jammed gate valve

Good luck!

I had the same issue a while back the valve would not close all the way causing the liquid to drain out (grey tank open) and leaving the solids. I took the MH to a repair facility (Charlie's in Utah) and they hooked up a macerator pump to the tank and after filling up the tank the macerator was used. That worked for about 1 minute till the pump froze from the so called flushable wipes jamming up blades (stainless steel) of the pump. The fix was to get the tank drained and then remove the valve and related plumbing to access the black tank where many of the so called flushable wipes were removed. It seems that one of the wipes got caught on a rough piece of plastic or something causing the valve not to close. Shoot three or four hundred dollars later I was a real happy camper :M

JimR

All of the above was very helpful, but flushing did not fix my problem. The good news is that it was easy to get to the valve in question. Only 4 bolts held it in place. Took it apart and yes there was a bit of tissue paper lodged and kept it from completely closing. While I was at it 4 more bolts took the gray water valve loose. Whole operation took about one hour. Key is flushing the tanks several times before starting. My advice, now that I've done this is........if ya can get to the valve easily, yank it out, clean it, make sure you put the gaskets back in properly, and you are done. Thanks to everyone for your help!

Wow! Compared to what we went through, your fix was simple!!
Glad it turned out so well ...