Can't pump out holding tank

[GiniL]

Mike: on your first question, whether I have an electric or manual head, there are two heads, and both are electric. One is the Tecma EZ fit. The other (almost never used) is a Raritan Sea Era (although I want to confirm that). Each has its own hose into the tank.

No sludge pump or other way to get the last of what's in the tank out. The macerator hose and the hose to the deck discharge are the only outlet points, other than the air vent line.

As for the suction on the marine dockside pump, I tried three different pumps. The third one is at a private yacht club where they keep it open all winter. It is known to be one of the best in the area, and a friend who is a member got me permission to use it. The story on it is that if you can't get a good pump out with it, you won't get one anywhere.

GrowleyMonster: I will try getting water into the tank via the deck discharge by pouring it in with a bucket instead of using the pressure of the hose line. A backup with the low pressure bucket fill and not with the hose pressure would be another puzzle piece suggesting a blockage of some kind. Thanks for that suggestion!

If that doesn't reveal anything, I will then try your snake-down-the-discharge hose suggestion next. It will be a few days before I can get back to the tank. At least that may give me a good idea about a blockage, if any. Sounds too dangerous for me to attempt compressed air to dislodge anything, so I'll leave the air compressor home. I do have an electric pump for my inflatable dinghy that has a max air pressure of 2.5 or 3 psi. If I were to try anything in terms of forced air, maybe that would be a safe option.

For all those options, I do worry a bit that all I might accomplish is knocking a blockage back into the tank and not being able to really clear it or get whatever it is out. Cross that bridge when I come to it, I guess.

Finally, there are no Y valves anywhere in the system. Each head empties directly into the tank. The macerator has its own line, with a bronze ball valve in the line to open and close it. The deck discharge has a dedicated line. So I'm confident the head (really, only one gets much use) is emptying into the tank.

It may several before I have time to do more on this project, but I will report back with anything I learn once I get farther down the path.

Thanks so much for those helpful insights!

Gini

[peghall]

Hi Gini... You have no problem emptying the tank using the macerator pump. That rules out another blockage in the vent line or a blocked tank discharge fitting. I think that only leaves one thing: Something is blocking the path from the tank to the deck pumpout fitting.

Is there a y-valve in the tank discharge line? If so, it has to be aimed to send tank contents to the overboard discharge pump and thru-hull. To be able to pump out the tank, the handle has to be turned to open it to the deck pumpout fitting...all the way over to the pumpout side. I suspect that the only reason you've been able to pump out at all in the past is because it was only partially open. Something as small as a grape seed can jam a y-valve, preventing the handle from turning it. So you may have to open it up to see what's going on in it that can be causing the problem.

If there' only a tee or wye the tank discharge line--no y-valve , there almost certainly has to be a blockage in it or in the discharge line above it. It could be something as simple as buildup or a wet wipe stuck in the hose or the fitting.

That's the best my limited psychic abilities can come up with from here....


--Peggie

[Mike Banks]

I read your post about no valves between the heads and the discharge into the tank. In mine the discharge into the holding tank is at the top of the tank. When you try to pump out the tank, see if any air is going in via the heads themselves.

If there is any way there is a problem in the suck-out pipe itself--the vacuum pump will simply draw air in from the heads themselves. This will explain why your sludge pump works and the pump out one does not. It may not be a blockage--just a leak inside the tank itself.


I know it is a bit of a long shot, but if there is a crack or hole in the draining tube, air will be drawn in through the breather and the heads themselves. I think you have to test the suck-out pipe for in-tank blockages, but how any significant objest could get into it through maceratiors remains a mystery--unless a tank-maker left a cleaning rag or sponge in it before sealing up the tank.

Having eliminated the possibility of a blockage, one has to suspect a leak in the top of that pipe itself--possibly a hole blown in it if it was welded into place, or if it was welded into a standard tank fitting, or simply badly fitted.

Does your tank have an inspection port? I do not remember whether it has been said or not.

[GiniL]

Hello Peggy,

Thanks so much for weighing in! I’m attaching a diagram of my system from the factory manual. It accurately shows what I found when I traced all the lines. The only valve anywhere in the system is the one shown as the “overboard shutoff valve” which is downstream of the macerator and cuts off any discharge through the port side thru hull. It is kept secured in the closed position with a stout zip tie.

My last boat had a Y valve that directed discharge either overboard or to the deck fitting. So I’m familiar with that system. The way this one is set up avoids that valve entirely. Instead, the macerator and deck discharge both have their own dedicated line.

The ball valve on the macerator line seems to close securely, but is there a chance it doesn’t? And would that matter with the macerator upstream of it? I’ve assumed that the macerator itself, when off, shuts the line off too. That may be a wrong assumption, or at least an overly optimistic one. Or perhaps any seal that the macerator forms could have gotten compromised by the vacuum created during my first few pump outs with a mostly caulked-closed vent line?

If nothing in the macerator line could be the cause, then things really are narrowing down to something in the dip tube or the line from the tank to the deck fitting. I think this may be my excuse to invest in an borescope, as GrowleyMonster suggested. I know I would get plenty of use out of it generally, and certainly for this kind of thing.

If any other ideas come to you, let me know. And again, I’ll update this with anything I learn once I can get back to my troubleshooting.

Thanks so much.

Gini

[Cadence]

You could have an air leak in the discharge line for pump out.

[GiniL]

Haven’t been able to identify any leak in the discharge lines, but until I have figured out the issue, I’m not ruling that possibility out! Thanks.

[peghall]

Gini, I think you said somewhere that the discharge fittings in your tank are on the top with pickup tubes (aka diptubes) inside the tank that go to the bottom. What are the tubes made of--pvc or metal?


--Peggie

[GiniL]

Peggie, they’re PVC. I’m attaching a few pics. The vent hose was still on in the first two, and removed in the third.

Gini

[peghall]

Those are good photos of the hose connections on the OUTSIDE of the tank...I'm asking whether the tube INSIDE the tank is PVC or metal.


--Peggie

[GiniL]

Peggie, ah, the dip tube inside. I don’t know the answer yet. I hope I will once I get an borescope (tomorrow) and, if it works as I hope it will, can get a look through the vent fitting on the tank or the discharge hose itself.

As accessible as those discharge hose connections may look in the photos, they are actually nigh-impossible for me to get to well enough to pull the hoses off. I have my arm and hand extended as far into that area as possible to get the pictures with my phone. I’m doubtful that I can crawl in far enough, with enough leverage, strength, and tool-maneuverability, to pull the hoses off to see what I can inside or (better yet) to pull the dip tube.

If I were to guess, I’d guess the dip tubes are PVC. Only because the PVC flange on top and the rubber sealing ring underneath it sure look like or are similar to this Dometic “universal” tank dip tube set up. But I hope to have a better answer in a few days.

Gini

[Cadence]

Originally Posted by GiniL

Haven’t been able to identify any leak in the discharge lines, but until I have figured out the issue, I’m not ruling that possibility out! Thanks.

A vacuum leak is a bitch to find. If there are any connections in the discharge line you might try wrapping them with Saran wrap (sp?) and see what happens.

[GiniL]

I did some more prowling around today. I got a small mirror down the tank vent fitting with enough light to slightly see the dip tube for the macerator line. Looks like black PVC. Will be able to confirm the PVC conclusion over the weekend now that I have my new borescope (which arrived while I at the boat). I think it will be a big help.

As for closing off any vacuum leak with Saran Wrap, worth a try! Maybe coupled up with some duct tape . . . I pushed myself a bit today and discovered I can skinny in to the discharge hose closer than I thought after unbolting and moving the macerator and lines to one side. The clamps on the discharge accepted a bit of tightening. Not a lot. But some. Having now gotten in far enough to get to the camps, I wouldn’t have any trouble getting some Saran Wrap and duct tape around both the deck fill and tank side connections for the discharge hose if it comes to that.

What I’m really looking forward to now is putting the borescope into the vent opening into the tank as well as down the discharge line and seeing what I can see. When I got home this afternoon, the borescope was here. It seems to good quality. I got one that allows for near and far focus. I can see the innards of the garbage disposal really well, so good close up focus. And far focus (10 ft or more) seems excellent too. This weekend I will take it onboard and hope it reveals some new info.

Ongoing thanks to those offering suggestions and encouragement.

Gini

[GrowleyMonster]

Originally Posted by GiniL

I did some more prowling around today. I got a small mirror down the tank vent fitting with enough light to slightly see the dip tube for the macerator line. Looks like black PVC. Will be able to confirm the PVC conclusion over the weekend now that I have my new borescope (which arrived while I at the boat). I think it will be a big help.

As for closing off any vacuum leak with Saran Wrap, worth a try! Maybe coupled up with some duct tape . . . I pushed myself a bit today and discovered I can skinny in to the discharge hose closer than I thought after unbolting and moving the macerator and lines to one side. The clamps on the discharge accepted a bit of tightening. Not a lot. But some. Having now gotten in far enough to get to the camps, I wouldn’t have any trouble getting some Saran Wrap and duct tape around both the deck fill and tank side connections for the discharge hose if it comes to that.

What I’m really looking forward to now is putting the borescope into the vent opening into the tank as well as down the discharge line and seeing what I can see. When I got home this afternoon, the borescope was here. It seems to good quality. I got one that allows for near and far focus. I can see the innards of the garbage disposal really well, so good close up focus. And far focus (10 ft or more) seems excellent too. This weekend I will take it onboard and hope it reveals some new info.

Ongoing thanks to those offering suggestions and encouragement.

Gini

Wow you got a much nicer scope than what I have. Got the link handy?

[GiniL]

Growly Monster, you may or may not want the same borescope. Mine is a Teslong, which I got on Amazon. Teslong appears to make two with autofocus/far focus. The one I got is here: https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1. Another that is less expensive, with nearly as good specs but a slightly smaller screen is here: https://www.amazon.com/dp/B07KD6BT1N...NsaWNrPXRydWU=. I sprang for the more expensive of the two because Amazon was offering a $50 off coupon and I had an Amazon gift card I could apply. By using those, I got the more expensive one for about the same price as less expensive one.

I'm glad I got it, but . . . the camera is wider than I realized and did not fit through my vent opening. I got it down the discharge line, but the 3 meter cable was a bit short to get all the way into the holding tank. My hunch is that I needed another foot or two.

So it wasn't the best tool for this job. I'm going to keep it, though. I like it a lot and have uses for it for several things on the boat and at home. Plus, I can add another camera/cable with a smaller diameter, which will give me lots of flexibility.

As for my progress with my holding tank issue, I keep narrowing things down without finding the problem. Here's the upshot of some of the additional things I've checked out:

• I can easily put water down the deck discharge hose using a bucket. I tried that to see what the flow was like without the pressurized water from a hose. The water went into the tank without any backup.
• I was able to get a plumbing snake down the line and into the tank. No hint of a clog.
• I'm as sure as I can be at this point that the dip tubes are black PVC.
• I have a low spot in the discharge hose that holds water. I discovered that when I put the borescope down the hose. I hit a short patch of water, then came out of it. I've now identified where it is and plan on eliminating it when I do whatever else will be needed to fix my issue.
• I put a 5/8 inch braided clear line down the discharge hose. Using a transfer pump, I pulled out the 5 or 6 gallons of fresh water that I had added to the tank and treated with KO. I was able to pull that water out without a problem. No sign of a clog or even anything even slightly mucky or solid. Pretty much clear water (of the kind you get after emptying a well-maintained holding and flushing it several times to layover for winter).

I may try one last pump out effort, after trying to seal off the deck discharge line as much as possible at both ends (saran wrap, duck tape, etc). I'm not optimistic I will see any change. The hose and clamps at both ends look fine and tight. If I don't have any success, I think that leaves the dip tube as the prime suspect. But that or anything else that requires pulling the discharge hose off the fitting into the tank is not going to be something I can do.

Frustrating. But I now know my sanitation system intimately. There's something to be said for that. At least, that's what I'm telling myself.

Gini

[Cadence]

Originally Posted by GiniL

I did some more prowling around today. I got a small mirror down the tank vent fitting with enough light to slightly see the dip tube for the macerator line. Looks like black PVC. Will be able to confirm the PVC conclusion over the weekend now that I have my new borescope (which arrived while I at the boat). I think it will be a big help.

As for closing off any vacuum leak with Saran Wrap, worth a try! Maybe coupled up with some duct tape . . . I pushed myself a bit today and discovered I can skinny in to the discharge hose closer than I thought after unbolting and moving the macerator and lines to one side. The clamps on the discharge accepted a bit of tightening. Not a lot. But some. Having now gotten in far enough to get to the camps, I wouldn’t have any trouble getting some Saran Wrap and duct tape around both the deck fill and tank side connections for the discharge hose if it comes to that.

What I’m really looking forward to now is putting the borescope into the vent opening into the tank as well as down the discharge line and seeing what I can see. When I got home this afternoon, the borescope was here. It seems to good quality. I got one that allows for near and far focus. I can see the innards of the garbage disposal really well, so good close up focus. And far focus (10 ft or more) seems excellent too. This weekend I will take it onboard and hope it reveals some new info.

Ongoing thanks to those offering suggestions and encouragement.

Gini

My suggestion of the Saran Wrap was to find the vacuum leak not necessarily as a long term cure.