Stubborn valve on Safari 27FB

[dpulling]

The blackwater dump valve on my 2008 Safari 27FB will not fully close. The drain cap says "Valterra" so I presume the valves are Valterra. I have always flushed the tank before storage (with the valves closed). The problem began after a winter which included a December hard freeze that (despite winterizing) broke plastic fittings at the toilet and the water filter.

I've used Thetford valve lubricant to no effect. The valve is located behind a galvanized steel enclosure, and can't be serviced without cutting away the enclosure to create a window. I can see that the valve for the grey tank has such a cutaway, which has been closed with a sheet of stainless (riveted).

My questions: Are there any other techniques for clearing this valve before I try to remove it? If I can't clear it, what is the procedure for getting at it without damaging the system?

I don't know if the valve is damaged or plugged, but next winter I think some antifreeze would help!

[nickcrowhurst]

That's tricky. What I would do as a last chance before the dreaded dismantling is:

1. Close the grey tank outlet valve.Open the black valve fully, but install the end cap over the combined outlet so that the black tank can hold water by virtue of the end cap, not the valve.

2. Fill the black tank with water, while slowly adding a complete box of Ridex drain clearer. Leave for a day or two. This will enable the Ridex to eat any biological residue by the black valve.

3. Remove the end cap, and let the fluid rush out in one full blast into a sewer.

4. Repeat the procedure but with clean water without the Ridex, and dump immediately. Repeat if you have time and enthusiasm.

5. Test to see if the valve is any easier to close. If not, the rubber seal may have torn. It's worth a try. Good luck.

Nick.

[Gene]

Another thought—if you have an item such as a Flush King, you can backflush with hot water (hose has come inside for that and you'll need a adapter) and see if that flushes out any debris. You could also try blowing it out with compressed air.

Gene

[CanoeStream]

Originally Posted by nickcrowhurst

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2. Fill the black tank with water, while slowly adding a complete box of Ridex drain clearer. Leave for a day or two. This will enable the Ridex to eat any biological residue by the black valve.

3. Remove the end cap, and let the fluid rush out in one full blast into a sewer.
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Nick? Between steps 2 & 3, would he have a better experience if he closed the valve most of the way before removing the end cap? And then open the valve right up again?

I agree that a digester is the right direction to go. Seems like he has some dried paper or gunk lodged in the valve.

[nickcrowhurst]

Originally Posted by CanoeStream

Nick? Between steps 2 & 3, would he have a better experience if he closed the valve most of the way before removing the end cap? And then open the valve right up again?

Bob, yes, I agree. When I've done this I've tried sawing the valve in and out a few times as the water rushes past. It helped a bit with mine, but it's still not as smooth as it should be, bearing in mind I serviced the valve 18 months ago.
Nick

[dpulling]

Thanks for the help, Nick, Gene and Bob. I hope it is a blockage that can be worked loose. First I will use the chemicals, then back-flush with the technique you've described. If that doesn't work, I'll be back with questions about where to make cuts in the tank enclosure!