Blackwater Valve Operation

by Michele

I own a 2009 Sprinter, which I bought secondhand. Tanks were empty upon purchase, or so I was told. I recently drained the black water tank for the first time. When I removed the cap, prior to opening the valve, about one cup of waste spilled out. I caught it and then proceeded to open the black water valve, which did introduce the remainder of the tank contents through the hose.

My question is this: what would cause the valve to "leak" that initial cup of material prior to my release/opening of the valve? And secondarily, how do I avoid this problem in the future?

Comments for Blackwater Valve Operation

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Aug 07, 2023
Don't leave dry
by: Mike

And as the tips say in this website, don't keep your tanks dry because they dry out. Even if you just put in a gallon or two of clean water for extended idle time. That might help extend the life of the seals.

Feb 17, 2017
by: Will

It's likely that the drain valve seal is no longer doing its job. I had the same problem on my black water tank. I just replaced the entire drain valve, which was very easy to do, and this solved the problem. The rubber seal eventually dries out and needs replacement. Any RV supply store will carry replacement drain valves.

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