Hunter 260 Holding Tank Vent Plugged

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May 17, 2010
81
Hunter 270 Ottawa
It appears that the vent on our holding tank might be plugged. Has anyone been able to unplug the vent without removing the holding tank ???
 
Dec 2, 1997
9,011
- - LIttle Rock
No need to remove the tank...

The two most common locations for a waste tank vent blockage are the vent thru-hull and the connection to the tank--both that end of the vent line and the tank vent fitting.

Start with the thru-hull...scrape it out with a screwdriver blade or whatever works. If that's where the blockage is, cleaning it out is likely to result a rush of air and MAYBE a spew...which is WHY you start there instead of at the tank!

If that doesn't seem to clear it, open the deck pumpout fitting very carefully...and hang on tight to the cap...to relieve any pressure in the tank. NOW it's safe to remove the vent line from the tank to scrape it and the line out.

To prevent a blocked tank vent in the future, backflush the vent line every time you wash the boat and/or pump out. If the thru-hull isn't designed to let you do that, replace it with that is.
 
May 25, 2004
958
Hunter 260 Pepin, WI
When I use the pump-out hose I can hear the air rushing in through the vent as the tank empties. If the vent is only lightly plugged, wouldn't pumping out the tank clear it?
 
Dec 2, 1997
9,011
- - LIttle Rock
When I use the pump-out hose I can hear the air rushing in through the vent as the tank empties. If the vent is only lightly plugged, wouldn't pumping out the tank clear it?
Nope. 'Cuz whatever has it blocked is either a buildup of "stuff" on the walls of the hose, a mud dauber nest... or (VERY rarely) a large insect that got stuck and died in it. None of those will be pulled out of the vent line and into the tank by a pumpout.

If you can hear air, it would prob'ly be a good idea to clean out the vent...'cuz a totally open one doesn't make any noise that you'd be able to hear unless you put your ear against the thru-hull.
 
May 17, 2010
81
Hunter 270 Ottawa
Holding Tank Vent Blockage Removed

Nope. 'Cuz whatever has it blocked is either a buildup of "stuff" on the walls of the hose, a mud dauber nest... or (VERY rarely) a large insect that got stuck and died in it. None of those will be pulled out of the vent line and into the tank by a pumpout.

If you can hear air, it would prob'ly be a good idea to clean out the vent...'cuz a totally open one doesn't make any noise that you'd be able to hear unless you put your ear against the thru-hull.
I removed the blockage & am not certain what worked. I put a pressure washer nozzle into the vent several times for a total of over 10 minutes, which did not appear to work immediately but might have resolved the problem overnite through soaking the plugging material. The next morning I inserted both a metal dental pick & a wire into the drain but could only get limited penetrqtion & saw no material come out. I then vacuumed the vent with a smqll wet vacuum. After that I filled the holding tank with a hose & found a full flow of water emerging from the air vent. I then refilled & emptied the tank several times to flush it & achieved clean water in the tank. However the tank will not empty completely, leaving it about one third full.
 
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