I cannot get my holding tank to empty. Assume it’s the air vent or physically clogged. Love to hear your ideas to clear
Holding tank won’t empty
- Thread starter SailorKP83
- Start date
No. I didn’t hear air being sucked in while attempting to pump out. Tried two different pump outs but same result
Not sure hearing is a definitive method compared with feeling it. If the vent doesn’t vent, you have the reason.
A shoreside pump would form a strong vacuum.
Is the top of the tank collapsing when being pumped out ? That's the proof of a plugged air vent.
Using shore water hose, force water into the holding tank vent. Does it look like water is going in. If not, at the holding tank remove the vent hose then try it.
Also pour water down the pump out hose. Does it go down to the holding tank?
Also pour water down the pump out hose. Does it go down to the holding tank?
I had the same thing happen once. The hose clamps for the pump out hose on my boat were loose. Does the marina's pump out hose collapse a bit indicating suction or is there no change when you press it against the por ton the boat?
Another possibility is that the internal pipe that goes down into the tank is separated or broken. If I recall the design correctly, there is a pipe that goes from the pump out connection on the tank down to near the bottom of the tank. The vent line goes into the top of the tank so when a vacuum is applied or the macerator is run, the suction is taken from the bottom of the tank through that pipe. If the pipe is blocked or if the pipe has separated from the connection the tank will not pump out. On a friend's boat, something got into the tank and "plugged" the pipe and he could not pump out.
If you have a Y-valve, check to make sure it’s in the right position. You could also run a plumber’s snake down the pump out line to make sure it’s not clogged. The vent line can be easily disconnected and blown with compressed air.
I had an intermittent situation where I could not pump out my Hunter 380 holding tank. It mystified me for years. I finally cut an access port in the top of the holding tank.
As previously mentioned, the pump out fitting on the top of the tank was extended inside to the bottom of the tank with a piece of flexible hose. The end of that hose was loose in the bottom of the holding tank. It was exactly the right length so that it could get wedged perpendicular to the inside of the holding tank. Attempting to pump out the tank just sucked the end of the hose onto the side of the tank so that nothing could pass.
The problem was solved by cutting an inch off the pumpout hose so that it couldn't reach the side of the tank.
As previously mentioned, the pump out fitting on the top of the tank was extended inside to the bottom of the tank with a piece of flexible hose. The end of that hose was loose in the bottom of the holding tank. It was exactly the right length so that it could get wedged perpendicular to the inside of the holding tank. Attempting to pump out the tank just sucked the end of the hose onto the side of the tank so that nothing could pass.
The problem was solved by cutting an inch off the pumpout hose so that it couldn't reach the side of the tank.
Or as a test, disconnect it from the vent side, if it still wont pump out, disconnect it from the tank side. As a last resort, you can try poking something such as a screwdriver in the tank where the vent hose attaches. If that's clear and you still can't pump out, then you know for sure that it's something in the tank or pump out line
You can also test that the shore side pump is working by placing the pump hose in a pail of water or stick it in the water next to the boat.
I didn't either. All my hose clamps were tight until I tightened them again under the deck pump out fitting. Then it worked fine. Sometimes the rubber creeps and things can get loose.
Another common cause:
Did you take ALL of the loops of hose off the rack before pumping? If not, the water has to rise 2 feet for every loop on the rack, yes, it will syphon once totally full, but it isn't to start, and if there are ANY air leaks, it never will be. Five turns on the rack can be an extra 15 feet of lift, added to the lift from your boat and hose friction, which the pump can't do.
Hose on the rack is bad. Lay it on the dock.
Many of the instructions leave off step 3, which really needs to be step 2. I guess they think it is obvious.
Did you take ALL of the loops of hose off the rack before pumping? If not, the water has to rise 2 feet for every loop on the rack, yes, it will syphon once totally full, but it isn't to start, and if there are ANY air leaks, it never will be. Five turns on the rack can be an extra 15 feet of lift, added to the lift from your boat and hose friction, which the pump can't do.
Hose on the rack is bad. Lay it on the dock.
Many of the instructions leave off step 3, which really needs to be step 2. I guess they think it is obvious.
Hmmmmmmmmmmmm ? ? ?
Not really. The pressure(s) in the loops are not additive. For every 24" of rise there's a 24" drop which hydraulically balances the previous rise.
