- March 21, 2020 at 9:55 am #12505
My waste tank is building a little pressure and I think the vent may be clogged. I have found a small plumber’s snake that will fit but the vent cap appears to be unremovable. How do you get into that vent? (I know the photo shows the wrong vent, but it was the easiest to take!)March 27, 2020 at 3:04 pm #12591Tom EasterbrookParticipant
If you open the deck pumpout, do you notice a change in pressure (escaping air, or the in rush of air)? You might try to clear the blockage (assuming there is one) by backflushing using water through that vent. Just make sure you are putting the water into the correct vent 🙂 I too, am not sure how to remove the outside cover.
TomApril 12, 2020 at 12:13 pm #12841
Thanks Tom. Here’s my saga so far. I removed the vent hose at the tank (in a very difficult location) and first shot some compressed air into the tank to be sure the blockage was not in the nipple (it wasn’t). Then I shot some air through the hose toward the hull-side vent but found it blocked tight. From the exterior, I tried to get a pipe cleaner into the vent to no avail; there simply isn’t room between the vent cap and the hose opening to get anything in. So I went back to the tank end and shot water through the hose. The only thing that accomplished was a test of the bilge pump. I also used the hose to blast water around the vent cap on the hull but nothing moved. Totally constipated. Next step: Turn the boat around so I can reach the vent cap from the dock and drill it out!
This should have been an easy job!April 23, 2020 at 9:32 am #12896Tom EasterbrookParticipant
I wonder how your vent got that plugged. I can only think of 2 ways (there might be more). First, the tank was “overfilled” and tank “contents” filled up the vent hose, later solidifying. Not fun, and definitely to be avoided. Second, some insect built a nest just inside the exterior hull fitting, blocking it off.
Let us know what you find, and yes, it should have been an easy job.September 19, 2020 at 12:02 pm #13169David C MorrisParticipant
Doug, hopefully this issue has been resolved by now,.but here is my input
We have a 2003 NT37 convertible and so I was able to access the blackwater tank vent hose where it was routed up behind the commode. I found the only way to remove / clean the vent was by removing the hose and then removing the nut that secures the vent through the hull. All this is done from inside the hull. The vent is then removed from the outside of the hull.
I ended splitting the panel behind the commode. I cut it in half horizontaly and and added a teak trim strip that covers the cut line. It looks pretty OK, and results in easy access to the area directly behind the commode where both the gray and black water vent hoses are routed up to their respective vents.
Your floorplan may be different so your access maybe different.
Cheers & Good Luck
Dave, Dot & Bailey Jean Puppy of MV CarouselSeptember 19, 2020 at 5:49 pm #13170
You made a good long-term solution to access those thru-hulls. I never thought of that, but I did drill out the vent cover, flushed it, and it works fine now. Thanks for your feedback.
-DougSeptember 20, 2020 at 11:41 am #13174David C MorrisParticipant
Glad to here you solved the problem. I went a bit overboard and installed a set of garden hose connections in our black tank vent line thinking that there might possibly be a recurring event? Anyway here is an image of our current layout / access to the vent.
Cheers Dave, Dot & Bailey Jean PuppyOctober 17, 2020 at 8:38 am #13196
That’s a good idea. In my case, I did a makeshift job of blasting water through it but it wouldn’t budge! Everything seems to be working now so I assume it had a spider nest in it or something like that. I’ve read that most tanks need larger vents or a second vent to keep O2 moving through. There is one product that is an aerator that pumps air into the bottom of the tank 24/7. I understand the science of that solution, but I’m not ready for that project! Or the additional power draw.
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