Grey tank valve

[sherman12]

Traveling with friends grey tank lever pulls open but doesn't dump. Knife valve stuck? Suggest fixes. Thanks

[Duckogram]

Is the blade valve a cable pull?

[D W]

If this is a manual hand-pull valve there a good chance that the rod has become dislodged from knife valve. Sometimes the rod pulls out the valve, other times the part of the valve that locks-in the rod has broken away. Does the handle/rod appear to operate without any resistance? Will the handle push all the way in? If so, the valve assembly probably needs replacing.

[sherman12]

Thanks to those who replied! Traveling I65 Nashville to Louisville (Bourbon Trail) our friends grey valve loosened open. The only problem for them was a wet bay full of grey water cause they didn't shut the valve right after it didn't work! Small problem and a roll of paper towels.

Another question though does the rod attached to the handle pull a cable inside the valve assembly or are there different types of knife valves? When you here lubricant your knife valves, I've always just sprayed the rod attached to the pull handles.