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Old 06-09-2018, 09:30   #1
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Can't pump out holding tank

I bought a 1978 Columbia 10.7 in December. We're slowly getting it back into shape, but I encountered an issue with the head recently. We have not done any long passages yet this year so we don't use the head often.

However, the other day we went over to fill up on diesel and pump out waste and we were not able to get anything out of the pump out port. We didn't hear any air being sucked in from the air vent.

I looked under the cabin sole and cannot see where the holding tank is and the owner's manual doesn't have a schematic. I have a feeling it is directly under the toilet itself, but has no access or inspection ports or hatches.

The sole of the head is not removable, although the toilet is. There doesn't seem to be any access to the hose ends and fittings, they seem to have all been installed during construction and no one thought you'd have to work on them in the future.

I've tried sucking and blowing air into the pump out port and vent using my shop vac with no effect.

I have a suspicion that something is clogging the vent tube which would create a vacuum and prevent the contents from being pumped out. But if I can't get to either end of the hoses or the fittings, how can I confirm this?

I can access the middle portion of both hoses but only through a cabinet in the head. I could cut the vent tube at this point and see if air can get into holding tank from that point. Then, I can rejoin the segments again with a hose connector.

Any other ideas?
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Old 06-09-2018, 12:52   #2
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Re: Can't pump out holding tank

I have a suspicion that something is clogging the vent tube which would create a vacuum and prevent the contents from being pumped out.

You're right...the problem is a blocked holding tank vent. Tank vents--all of 'em, water, fuel and waste--have 2 essential functions: 1. to provide an escape for air displaced for incoming contents. When air can't escape, the tank--the whole system--becomes pressurized, which can have some very interesting consequences...the least of which is a geyser out the pumpout fitting when the cap is removed, a backup,even an eruption in the toilet. 2. to provide a source of air to replace tank contents as they're sucked out. Without it, the pump pulls a vacuum that won't let it pull more than a gallon or two out, if that much.

Forget about using a plumbers snake to clear it 'cuz rarely does anything block the vent LINE. The two most common locations for a vent blockage are the vent thru-hull and the other end of the vent line--that end of the hose and the vent fitting on the tank. Start with the vent thru-hull...use a screwdriver blade, ice pick...whatever works to scrape out whatever is in it. If there's a screen in it, knock it out...screens create more problems than they solve because they get clogged with dust, pollen and corrosion. If you're lucky, that'll the only place it's blocked. If not, you're gonna have to create access to the tank. I just googled "columbia sailboat forums" and came up with several...I'd bet you can find help on at least one of 'em.

I can tell you it's POSSIBLE but very unlikely that the tank is an OEM installation...for two reasons: 1. federal law requiring holding tanks didn't go into effect until 1980 and few if any states began enforcing earlier than 1985...and 2. If the hoses were original, they'd be so hard and brittle by now that they'd be cracking and splitting...you'd have leaks everywhere. So some PO had to have gained access to that space to install the tank. Even if the hoses aren't original, if they're anywhere near 10 years old, they should be replaced too.

Once you know how to get to the tank in vent line, there's a bit more info that should help you if cleaning out the thru-hull didn't solve the problem.Remove the vent line from the tank--but first open the deck pumpout fitting VERY carefully, with a hose at the ready to relieve any pressure in the tank...and scrape out that end of the hose and the vent fitting on the tank. Put the vent line back on the tank.

There are a few more possibilities: a kinked vent line, or a sag in it where liquid has pooled, or a filter in the vent line. If a filter ever gets wet--which can easily happen on a sailboat due to heeling--the charcoal swells and blocks the vent.

So you have a bit of work to do, but now you know WHAT to do and should be able to find out how to do it.

Fwiw, you might consider checking out the link in my signature...the title (my publisher's idea) is a bit misleading. Although it does deal with every source of odor on a boat and how to cure--better yet PREVENT--'em, it's actually a comprehensive "marine sanitation systems 101" guide that can help you learn to prevent 99% of problems instead of having to cure 'em. And I'm always glad to answer any questions it doesn't.

--Peggie
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Old 06-09-2018, 13:56   #3
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Re: Can't pump out holding tank

Peggie,
Thanks for detailed reply. Lot's of good information. As a DYI auto mechanic, I am always surprised at how auto companies make it almost impossible to fix or replace certain parts on a car. I think many boat manufacturers have them beat in spades.
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Old 06-09-2018, 14:15   #4
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Re: Can't pump out holding tank

You are correct, the vent line does have a screen on it. I was wondering if I should knock it out or not. Now I know.
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Old 06-09-2018, 17:09   #5
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Re: Can't pump out holding tank

Once you've gotten rid of the screen, put a hose nozzle against the thru-hull and backflush the vent line with as much water pressure as possible...use a power washer if you have one so the water can flush out the connection on the tank. If the clog has turned into impenetrable 'cement,' worst case you'll get a little wet from the back flow. May not work, but it's worth a try.

Once you do manage to open up the vent, you can keep it open by putting a hose nozzle against it to back flush it every time you wash the boat and/or pump out

You're welcome to give me a shout any time you have a question I should be able to answer.


And AMEN to boat mfrs paying -0- attention to whether equipment is accessible. They're the worst sanitation system plumbers on the planet!



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Old 06-09-2018, 18:53   #6
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Re: Can't pump out holding tank

The other possibility is that there is no holding tank and that the hose leading to the deck pump out has a plug put in it. Do you have a Y valve? Is there a through hull? Maybe it just plumbed to pump outside and you don't know. Stranger things happen.
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Old 07-09-2018, 08:58   #7
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Re: Can't pump out holding tank

Quote:
Originally Posted by Thumbs Up View Post
The other possibility is that there is no holding tank and that the hose leading to the deck pump out has a plug put in it. Do you have a Y valve? Is there a through hull? Maybe it just plumbed to pump outside and you don't know. Stranger things happen.
I have had the same idea but was afraid to suggest it...
Easy to check - if there is a tank it should have a provison to empty it out into the sea with a seacock.
If you do not have such seacock/valve there is no tank and you are trying to suck out a pipe installed to be connected to future holding tank.
I hope you do have a tank though and Peggie's advice will free the clog!
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Old 07-09-2018, 10:12   #8
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Re: Can't pump out holding tank

I have two holding tanks on my boat and it's very common for the forward tank to not pump out. We've discovered that we simply run some water down into the tank from the deck and then the pump out works. Never have that issue with the rear tank, but more often than not on the forward one.
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Old 07-09-2018, 10:17   #9
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Re: Can't pump out holding tank

Quote:
Originally Posted by Bigjim View Post
I bought a 1978 Columbia 10.7 in December. We're slowly getting it back into shape, but I encountered an issue with the head recently. We have not done any long passages yet this year so we don't use the head often.

However, the other day we went over to fill up on diesel and pump out waste and we were not able to get anything out of the pump out port. We didn't hear any air being sucked in from the air vent.

I looked under the cabin sole and cannot see where the holding tank is and the owner's manual doesn't have a schematic. I have a feeling it is directly under the toilet itself, but has no access or inspection ports or hatches.

The sole of the head is not removable, although the toilet is. There doesn't seem to be any access to the hose ends and fittings, they seem to have all been installed during construction and no one thought you'd have to work on them in the future.

I've tried sucking and blowing air into the pump out port and vent using my shop vac with no effect.

I have a suspicion that something is clogging the vent tube which would create a vacuum and prevent the contents from being pumped out. But if I can't get to either end of the hoses or the fittings, how can I confirm this?

I can access the middle portion of both hoses but only through a cabinet in the head. I could cut the vent tube at this point and see if air can get into holding tank from that point. Then, I can rejoin the segments again with a hose connector.

Any other ideas?
Check the vent for being clogged by a mud dobbers nest, wasp.
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Old 07-09-2018, 10:17   #10
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Re: Can't pump out holding tank

We have a Tartan 27-2, built in 1978. When we first got the boat, there was a holding tank under the Vee berth adjacent to the head compartment. It may of been retro-fitted. I could not stop the head from leaking, so i put in a Porta Potti and took the rest of it out. This was a good solution for us, since due to work schedules, getting more than a few days at a time to go anywhere is rare. When we can go further, we will probably need something else, since about 5 days is max we can go without emptying it. Ashore of course.
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Old 07-09-2018, 10:19   #11
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Re: Can't pump out holding tank

When we were still in Florida, our marina put in a new pumpout system which was much more powerful than the old one.

However, our boat took even longer to pump out.

It turned out that the suction was so strong that our vent hose would collapse.

With a new vent hose, it was empty in under a minute.
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Old 07-09-2018, 13:33   #12
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Re: Can't pump out holding tank

Sounds like sludge on the bottom of the tank may be blocking the tank discharge fitting, that adding water is thinning it enought to pump out. Holding tanks should be flushed out 2-3x year--and especially in preparation for winter or other extended layup to eliminate any sludge. It's not hard to do and it's not necessary to fill the tank to do it: Put enough water into the tank via the deck pumpout fitting--'cuz that sends the water into the tank at the bottom to stir up the sludge and hold it in suspension so it can be pumped out--to cover the bottom to a depth of 4-6'. Pump that out. Repeat...repeat...until you're pumping clean water. Then put a few gallons of water into the tank one more time and turn on any overboard discharge pump to rinse out the pump and its related plumbing.


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Old 07-09-2018, 13:39   #13
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Re: Can't pump out holding tank

Hello,
Our 1969 columbia28 has a tank under the fwd portside settee seat , just adjacent to the head on other side of the bulkhead. Its stainless steel and connected to a macerator. Ive never pumped it . We bagged and bucket it for marina disposal. I think theres two y valves and they're both stuck. The plumbing is a nightmare! I should take a pic and send it to Peggy . Lol
I will say this , the vents will plug! Mud daubers will concrete them shut!
But hot water and a wire snake should do the trick ! Follow with pressurized water or air, BUT, consider where you are blowing it! You dont want to blow it into your fresh water or fuel tank do you ? Black tank sure !
I had a very difficult time fueling up to original fuel tank, so slow that anyone waiting for me got frustrated. When i replaced the tank, I discovered a loop in the vent hose and mud in the vent. Water had accumulated in the loop.
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Old 07-09-2018, 13:45   #14
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Re: Can't pump out holding tank

Are you aware of "MSD" portapotties? The "MSD" designation in the model name/number means it has fittings for a pumpout line and vent line, and is designed to be permanently installed (actually just sturdier brackets than portables, so you could still take it off the boat if you absolutely have to), which means that although it's still called a PORTApotty, you don't have to carry anything off the boat to empty it. A 5-6 gallon model holds 50-60 flushes (which sounds like the size you have if it lasts 2 people 5 days)...you'd need at least a 30 gal tank to hold that many from a manual marine toilet. No plumbing needed except a vent line and pumpout hose...unless you want to install a y-valve and pump to empty it at sea. If you're handy, you could prob'ly DIY a pumpout fitting and vent fitting on the tank yourself. A li'l gadget called the Uniseal UNISEAL, a little PVC pipe and some hose is all you'd need.T'would be worth the effort 'cuz a full 5.6 gal tank weighs about 50 lbs, which is a lot to carry off the boat to dump it.



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Old 07-09-2018, 14:12   #15
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Re: Can't pump out holding tank

There should be three or four things visible if you have a holding tank,.
The outlet for an external pump-out,which is on deck the carbon filter to absorb smells and the outlet therefrom, which is usually just below the scuppers, but the tube to it from the filter is inside the hull, the Y valve for the diversion from the holding tank to the At-sea discharge through-hull, and the siphon breaker that prevents sea-water re-entering the tank if you do use the sludge pump usually mounted just ahead of or behind the tank itself.

Almost any of these can be blocked--but the sludge pumps have a different noise as the diaphragm pumps up and down as the waste is discharged.

Any of these can be causing a problem. I would start with the manually operated valve between the sludge pump and the tank. Make sure it is open--otherwise nothing is happening.

If that is OK and pump seems to be working, it may be a faulty Y-valve as like as not. I never liked them, so I use TWO ordinary ball-valves made of a type of plastic, in each of the legs of a Y joint. More fiddly, but easy once you remember which is which.

First rule--make sure all the necessary valves are OPEN or the discharge from tank to discharge sludge pump can not happen. I suspect THAT is your problem.
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