Waste Holding Tank Vent Line

[srokag44]

I had the marina attempt to pump out my waste holding tank for the first time yesterday. They told me that they were able to get about 5 gallons out before it stopped flowing. They thought there was quite a bit of vacuum being developed in the holding tank and suggested that it may be caused by a clogged vent line.

I looked at the vent line where it enters the tank and have attached a picture. Can anyone identify this and tell me if the three wires are for some sort of shut-off valve on the vent line?



Thanks!
Gary

[ready123]

Are you sure that is the vent line? It seems to be too close to the outlet inmy view. Could that be the wiring for tank level?

[Stripermann2]

Maybe for a level sensor. An old level sensor...

The vent should always be open, there should be no valve operated electrically.
If the tank was pressurized, you'd see it bulging...and if you opened the deck cap to pump out and it was pressurized, you'd know it too. Don't ask how I know...

Just pull that hose off and look, then you'll know for sure, if you can see down into tank and there are no obstructions out through the through hull vent, you're not clogged.

If you're talking about sludge in the tank after liquid removal, dump a couple of bags of ice in the tank, go for a wild ride...with some twists and turns and then pump out again.

[srokag44]

Level sensor makes sense... there are two "3/4" and "full" indicator lights by the head that do not work.

I was hoping to avoid having to pull any hoses off of what I believe is a full tank but looks like I'll be plugging my nose and diving in this evening.

[sluggo]

this job, I am pretty sure those wires go to the holding tank level indicator, mine is in the head. I have removed that hose and unsrewed the plate to get into the tank, no fun there, but it was the only way.

we pumped it out with a hand pump into buckets!! I hope not to have to do that job again.