Hi Arn,
Yes, it definitely sounds like you have a leaking flange seal. If you are not getting the whoosh and you are getting some leakage when you open up the sewer cap, those are key signs. The whoosh sound is from the air in the black pipe below the toilet being displaced by the incoming waste -- the air comes up through the waste as bubbles. If you don't hear that, no air is being displaced, and that means that black pipe is already full.
I think your suggested method is certainly an acceptable work-around for this problem. However, I think it does have some disadvantages:
- Camping in sub-freezing temps might pose a problem as that pipe is below the floor and might freeze. But for that matter, so is the gray water pipe that leaves the tank, so maybe that's not an issue, but it sure would be a bummer if it cracked.
- You lose the extra capacity to be gained by opening the EZ valve when your toilet is getting full. This has saved me numerous times.
- I think the "whoosh" helps funnel solids down into the black pipe, as it's a fast downward flow of waste from right inside the filter cone. If you aren't dumping at your campsite (vs. your campground or elsewhere), I think that's probably very helpful in evacuating most of the waste. Otherwise, once you drive around a bit, you give solids a chance to move outside the filter cone, and once that happens, it takes awhile for them to move back in, at least in my experience.
Can't think of anything else really. I think this is probably how "regular" RVs are setup, i.e. that black pipe is always full. But like you said, it's certainly easier than replacing the seal!
Dave