Holding tank plumbing help...

[ChrisSanJuan]

So I have some holding tank issues and I'm at my witts end, hopefully someone here can help!

Here is the breakdown:

Recently bought a San Juan 34 sailboat. The head was pretty new, about 1 year old with very little use.

The plumbing configuration is the head discharge goes through a vented loop mounted near the top of the deck level, then back down into the holding tank. The holding tank out goes to a Y Valve. The Y valve either has a hose connected directly to deck pump out, or the other side goes into a macerator pump, then to the ocean dischange valve. There is also a small 5/8 clear hose coming out of the tank that leads to a vent thru hull near deck level.

The Issue:

We used the head for a bit and seemed to work fine. But now any liquid flushed comes back into the bowl bubbling up within about 2 minutes. We tried to pump out the tank and the Y valve was set to the correct position for this. However when we tried, it only created a vaccum and would not pump out any actual waste. I thought this meant air could not get into the tank to displace the waste... So I disconnected the clear tube from the thru hull vent which was corroded and very old. I ran the hose outside to fresh air to air could get in. Tried to pump out again, still just created a vaccum and no waste came out. Then when I tried to pump the head with the vent hose disconnected, waste came out of the vent hose!

Right now my plan was to start disconnecting hoses to look for a clogged one and replace it. Also replace the vent hose and thru hull. I am thinking of disconnected the head outlet at the Y valve so I can at least get the thing pumped out directly. However I'm trying to figure out how to do this without spilling sewage into the bottom of the boat!

[The Garbone]

Sounds like your Y is still closed or the tube is clogged. Put some water down the deck pump out fitting until it if full. Fiddle with the valve till the level changes.

Worse case you need a plumbers snake to clear a clog.

[ChrisSanJuan]

The Y Valve could be the issue. It's defintely in the correct position for pump out. But its also frozen. I can't move it from pump out to overboard position. I suppose that being the case, maybe its clogged up too.

[meridian28]

My discharge valve was broken although I didn't know it at the time. The handle would turn 90 degrees but it was really always open.


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[TrentePieds]

Get down and dirty.

1: Disconnect the vent tube opposite end to the holding tank. Blow though it. Use a compressor with an air-pistol if squeamish. If air goes through it, then there is no problem there.

2: Pull the "Y". Once you have it in your hand, you can look into any one of the orifices to observe the function of the rotary valve within. Clean as necessary and reinstall. Wear sanitary gloves if squeamish. 15 minute job that confers certainty.

3: Get a bung for a wine carboy. get it from a "Make you own Wine" store. It has a hole in the middle. Stick it in the pump-out deck outlet. Stick the air-pistol from your compressor down the hole in the bung and blow gently. If bung blows out, there is your blockage. If it doesn't go to 4:

4: Pull the macerator and clean it. Bench test that it runs okay. Use the bung and compressor trick on the hoses. If the "to Ocean" hose is clear, the air will blow through it. If the tank-to-macerator hose is blocked the blockage will likely blow back in to the tank.

Sometime during this routine the problem will be come obvious. As always, correct diagnosis is 90% of the job.

TrentePieds

[bobfromcanada]

Double check the position of that Y-Valve. When we bought our 41 a few years ago it had a fancy head system with three valves. You could pump out from holding tank thru the deck fitting (conventional pump out), pump out the holding tank overboard, or direct discharge overboard, all depending on valve positions. We removed all the selection valves but left the Y-Valve in case we ever go off-shore and out of reach of pump-out facilities. Interestingly, the valve handle points to the direction that's blocked, not the one that's open. Not what I would expect. I added a label to the valve to jog my memory in case we re-instate that system.
I'd bet that's your issue.

[zstine]

Run a plumbers snake/drain Auger ($10 - $20 at HomeDepot) from the pump out deck fitting and ensure it is getting into the tank. If the Y valve is stuck and NOT open to pump out. go for a sail and try to discharge via the macerator / through hull.

On a separate note, I could not pump out and I over filled my tank and had waste come out my vent the shortly after buying my boat, just like you. The reason the pump out wouldn't suck waste was small air leaks in the old dry rotten rubber hose... I know your hose is new, but it can't hurt to check to ensure the ends are properly clamped so air can't get in.. Though a bad or clogged Y valve is more likely.

[Dave22q]

You have an overfilled tank. Your 'Y' valve or the hose from the tank may be blocked. Try disconnecting your vent hose at the hull and apply suction to the pump out port. If you get no suction on the vent hose the valve is in the ocean dump position or an outlet hose is blocked. If a hose blockage one easy thing you can try is run hot soapy water down the deck pump out port until full. Let it sit for a half hour and try a snake. Then apply suction again again. If you only get back the water you added you will probably have to deal with your valve. If you can get to the ocean outlet with your suction pump, switch your valve to dump and try to suck it out that way. Again if suction on the ocean outlet does not create suction on the vent hose you have a block most likely on the hose from the tank to the 'Y' valve or inside the valve itself. Then it gets a little messy because the hose from the tank to the valve is probably full.

[denverd0n]

Unrelated to your other issues, you do not need a vented loop between the head and holding tank. You only need a vented loop if it is possible to make a direct connection between the head and a discharge seacock. The holding tank itself, because it is vented, is like a big vented loop. A siphon cannot be created between the discharge seacock on one side of the holding tank, and the head on the other side.

See here for more details: Installing a Head by Don Casey - BoatTECH - BoatUS

[Stu Jackson]

Originally Posted by Dave22q

You have an overfilled tank. Your 'Y' valve or the hose from the tank may be blocked. Try disconnecting your vent hose at the hull and apply suction to the pump out port. If you get no suction on the vent hose the valve is in the ocean dump position or an outlet hose is blocked. If a hose blockage one easy thing you can try is run hot soapy water down the deck pump out port until full. Let it sit for a half hour and try a snake. Then apply suction again again. If you only get back the water you added you will probably have to deal with your valve. If you can get to the ocean outlet with your suction pump, switch your valve to dump and try to suck it out that way. Again if suction on the ocean outlet does not create suction on the vent hose you have a block most likely on the hose from the tank to the 'Y' valve or inside the valve itself. Then it gets a little messy because the hose from the tank to the valve is probably full.

That's my guess, too. Disconnect the vent hose AT the tank, too. Good luck.

[captlloyd]

Get ready, here it comes, go to a composting system and never have to fear blowing sewage all over your bilge.