Plumbing fascinoma

[Hippocampus]

Have trouble pumping out. Doesn’t matter if shore based system or pump out boat.

Overboard works perfectly. Empties tank in <5 minutes completely. Few air bubbles at start for <5-10 sec then just overboard flow. Pump out via deck fitting is either no flow or anemic flow with short bursts of good flow until 1/2 empty. Then no flow.

Can hear air flow in vent if listen closely.

System is fiberglass nipple on top of fiberglass tank. Reaching into tank can feel tube down to bottom. From nipple hose to Tee fitting. From Tee one hose to overboard through hull. Other arm to deck fitting. Originally there’s e was a mix of multiple right angle bends, hose and pvc pipe. Thought there were air leaks so took that run out completely and replaced with a single run of new sanitation hose (1 1/2”). No right angles rather more gradual bends and only connections are to tank pick up and deck fitting and the Tee which I replaced. All doubled clamped with new SS hose clamps. Can’t hear any air leaks anywhere.

Still normal great emptying via overboard and no emptying via deck pump out. Run to through maybe 3’. Run to deck fitting maybe 10-11’.

This one has me stumped. Not behaving like a clogged vent and took off plate for tank tender while pumping out which made no difference. Don’t think it’s a clog as all new hose and fittings except deck fitting which looks just fine. Also both overboard and deck pump out use the same pick up tube. Had trouble with attempts at different places so don’t think it’s due to poor pump out stations. Have no idea what’s going on. Going pass 3m every time is not a good solution.

Any thoughts on what I’m missing?

 

[Cigatoo]

When pumping from deck any signs of hoses down below collapsing? It has to be sucking air or creating a vacuum. Any changes if you close the thru hull or block off the vent while pumping? That’s a fairly new boat isn’t it? Why have hoses been changed?

 

[mvweebles]

Is this a new problem - has it worked well in the past?

The leg of the Tee that goes to overboard discharge, does it have a vented loop (it should)? Any chance that when you're sucking out the 10-11 foot of deck pumpout that path of least resistance is sucking air, not effluent?

Peter

EDIT: isn't there usually a Y-Valve vs a Tee so one leg is firmly closed off?

 

[Porgy]

I’ll wild guess that the discharge pump has a small leak. Maybe a flapper valve or check valve isn’t closing completely. When pumping overboard it’s not bad enough to fail and once it gets suction works ok. But during shoreside pumpout, it sucks air from that side of the T instead of effluent from the eduction tube. (Eduction tube- I learned that one from reading technical manuals about RR tank cars. )

 

[Hippocampus]

Hoses don’t collapse but they are new reenforced trident. Wouldn’t expect them to collapse with degree of vacuum usually seen with pump outs. Can see effluent half way up translucent Tee but no further when attempting to empty.

Vent for tank is independent of both arms. Vent goes to tank directly.

Haven’t found a vented loop on arm to deck fitting. Neither what we took off or put back. No vented loop on arm to thru hull either. Only section before Tee has maybe 1’ is below waterline so see no reason for a vented loop. It’s a closed system only flooding risk is if thru hull fails.

Prior owner replaced sanitation plumbing prior to my purchase. I don’t know why. Assume permutation of original hose.

Yes it worked fine for the first 6m of ownership.

 

[Hippocampus]

Great thought porgy. I didn’t think of that. Didn’t hear it so didn’t cross my mind. Thanks so much. Now to find more information on servicing that pump.

 

[mvweebles]

Only thing I can think of is there must be an air leak somewhere. Probably not practical to cap-off Tee that goes to overboard. Maybe while trying to pump-our through deck fitting, spray some water around fittings and see if a hiss makes itself known?

BTW - thanks for the word-of-the-day (facinoma). New one for me.

Good luck. Hopefully someone will chime in with a silver bullet

Peter

 

[twistedtree]

I agree with Weebles and Porgy that the problem is likely related to the tee, and that air is being drawn in from the other branch. The most conclusive test would be to plug the branch to the discharge pump. Most suspect for the actual problem would be your discharge pump duck bill valves and/or diaphragm.


Coincidentally, I am currently having the exact same problem, however my deck pumpout has it's own pickup tube, so likely a different cause.

 

[Porgy]

I have also had occasional issues with pumpout deck fittings that weren’t airtight, whether the rubber nozzle or screw-in type. And, once or twice the marina’s shoreside pump lacked enough power to get sufficient suction.

 

[Hippocampus]

Think I’ll pursue air leak on the overboard arm first as deck fitting looks to be in good shape. Did have them try with the screw in and the rubber insert type. Made no difference.

 

[HeadMistress]

Consider replacing the tee with a v-valve or better yet, add a second discharge fitting with a pickup tube in the top of the tank (easy to do, thanks to a li'l gizmo called the Uniseal UNISEAL if you have enough clearance above the tank to use a power drill with a hole saw bit), giving you dedicated pumpout and overboard discharge lines.

Meanwhile...holding tanks need a little maintenance. How often do you thoroughly flush out your tank? Sludge can build up on the bottom of the tank partially clogging the pickup tube..so can a wad of TP. That should be done at least a couple of times a year/season...and it's easy to do:
Pump or dump to get the tank as empty as possible, then add 4-6" of water to 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 sucked out ...pump or dump that out. Repeat, repeat till you're pumping/dumping clean water.

If your toilet uses sea water it's also possible that sea water minerals have built up in your tank discharge lines, same as it can in the toilet discharge line. A healthy dose or two of muriatic acid, available from any hardware store, added to an empty tank, then pulled through the pumpout and discharge lines will clean 'em out. Wait 45 minutes, then follow with plenty of clean FRESH water.

A couple of "top of the head" suggestions that can't do any harm, but may solve the problem..


--Peggie

 

[Comodave]

Probably an air leak in the discharge pump side of the T. Can you put a shutoff valve on the discharge side of the T and keep it shut when using the deck pump out and only open the valve when you are going to use the discharge pump overboard?

 

[Stout]

Hip, if you have looked at the duck bills in the macerator pump and they are ok, do you still have the original ABS tee? Where the NPT barbs screw in, the ABS tee will eventually develop cracks where the barb screws in, this can cause vacuum leak also. Hope this helps.

 

[Hippocampus]

Replaced all the fitting’s including Tee.

Have completely emptied tank and filled with fresh multiple times.

Have no idea what P.O. did we only use fresh and toilets are only plumbed for fresh.

Have small paper bags (buy a 100 at a time) which are in small garbage cans next to each toilet for TP and female needs and baby wipes. Nothing that hasn’t come out of people goes into the heads.

Have placed bacteria into the heads. Other than an occasional mineral oil no chemicals.

Have thought of replacing Tee with a Y. But if it’s a pump leak it needs to be rebuilt anyway so will do that first. Thought about putting a wood plug in hose to pump and seeing if pump out worked. But have already rebuilt one vacuflush pump and its bellows were shot. Figure Porgy got the prize so rather than messing with things I’ve already replaced with just rebuild the pump. Parts via Amazon were 1/2 the price of WM but have to wait until Wednesday for them.

 

[Stout]

Sounds like you have been methodical on this, hopefully just the macerator duck bills. Another thought is back flushing through the deck pump out to see if water drains fast back into the tank with no restriction.

 

[Hippocampus]

It back flushes beautifully. Also all the pipe and hose we took out was free and clear. No mineral deposits, no growth, no obstructions. Lumen was wide open.

Would you just replace the duck bills or totally rebuild the pump?

 

[mvweebles]

It back flushes beautifully. Also all the pipe and hose we took out was free and clear. No mineral deposits, no growth, no obstructions. Lumen was wide open.

Would you just replace the duck bills or totally rebuild the pump?

Replace the pump with new and rebuild old for spare? Keeping things clean is difficult with each teardown and reassembly. If you can survive with it fallow for a couple days, might make sense to buy new (that said, the Jabsco macerator pump I once replaced was DOA, but not obvious- would run for 5 seconds, then shut down).

Goof luck Hippocampus

Peter

 

[Stout]

We carry a spare rebuilt pump and would do as Peter suggests. The macerator pump is less $$ than the vacuflush pump.

 

[plittle2005]

FWIW, I could not pump out. I found that my pump-out hose deck fitting had completely corroded thru just below the deck inside surface, break could not be seen from outside, found it by reaching WAY in and wiggling the hose. Replaced that fitting (PITA location!) and all is fine. G*d%mn Zamac metal fittings!

 

[AlanT]

I have occasionally had a similar problem due to a non-airtight connection where the dockside hose nozzle is inserted into the boat's sewage deck-fitting. Easy to check if this is the case by hosing some water around the connection while pumping. If it starts to get suction you have a poor connection. That can be a fault of the deck fitting or the dockside nozzle.
~A

 

[Hippocampus]

Put in a Y valve. With that closed was able to pump out. Yay!!!!

Overboard pump is a dometic TS. Have rebuild kit for it. But it works fine so didn’t install it. Ain’t broke don’t fix it. Have duck bills for it as well but they look fine so again won’t replace.
It a long run to the deck fitting. About 12-13’. Needed pump out boat to prime perfectly then it worked. If I have further problems with replace deck fitting. Did use screw in fitting for pump out which I think you always should if available.

Thanks all. Especially suggestion to eliminate the overboard arm from the equation.

 

[BruceK]

Put in a Y valve. With that closed was able to pump out. Yay!!!!...

Remember to "exercise" the Y valve occasionally, otherwise they can get stuck. "Seized" is probably too strong a word, they may be mobilized with heat,eg. using a hair dryer.

 

[Hippocampus]

Thing is plastic. I’d be reluctant to put heat on it. Before installing put tons of grease on it. But thanks for the reminder to cut the zip tie making me street legal and giving it a few turns time to time.

 

[DW1979OA]

The assumption that the shore and pump out boat were both working properly could be the issue. Maybe a third option pump out location would eliminate that possibility.
I’ve had issues pumping out in Everette by the fuel docks where it wouldn’t build up suction because it was a two station and the valve at the other station was not closed completely. Also on the guest docks there is a long run back to the pump and it takes a long time to build up enough umph to get things moving.
Good luck

 

[Hippocampus]

One place was a fuel dock with pump out at the dock. There was just one set up. That was north/south Carolina border. Other was a pump out boat that had no trouble pumping out other boats. That’s Hilton Head. For now my assumption is it’s us not them.
Won’t know for sure until our travels continue. That should be end of march. Takes at least 3 weeks for the 2 of to need a pump out.

 

[HeadMistress]

Remember to "exercise" the Y valve occasionally, otherwise they can get stuck. "Seized" is probably too strong a word, they may be mobilized with heat,eg. using a hair dryer.

A blow dryer doesn't generate enough heat to do any harm to hoses or hard plastic equipment...I kept one in my tool box to use, mostly to soften the ends of hoses enough to remove or put them on fittings.

It's also important to lubricate y-valves and other things that rotate or have moving parts 2-3 x year. "Seized" would not be too strong a word if you don't. Thick silicone grease is a good choice.

--Peggie

 

[SIBERNUT]

What is this in the waste system?

I have asked on the forum several times, but now have pictures. These pics are of (I guess?) a poop "day tank" thing. It is under the sink counter in the head close to the hull & higher than the throne

. Very difficult to diagnose thru access under sink. It is SS, and in the deck above is a "waste" port. There is a MASSIVE waste tank in the stern also with a "waste" port. Head is manual but I can't tell what all is in the compartment & this boat is all new to me after taking a swim (boat took a swim, not me). Give it your best shot, pls.

 

[HeadMistress]

Oh dear...the whole system is a disaster! Corrugated hoses should never be used in sanitation system plumbing...worse yet, urine is so corrosive that it'll turn even 316 SS holding tank into a colander in an average of +/- 10 years...which is the reason why plastic became the recommended holding tank material in the early '90s. The good news is, your description indicates that it's small, so will be relatively inexpensive to replace if you decide to keep a tank there. There still a few owners of older boats who insist on replacing aluminum or steel holding tanks with new ones, but very few now. Hopefully the "massive" waste tank in the stern isn't metal.

What's in what appears to be a box with a shoebox lid on it in the lower right of of your lower photo?

If you'd like my help to sort out everything you need to do to end up with a trouble-free, odor free system without breaking your boat's piggy bank...send me a PM. I'd be glad to do that.

--Peggie

 

[Comodave]

Take Peggie up on her offer, she is the guru.

 

[SIBERNUT]

I will ! She knows her s**t, hih?

Biggest problem will be just getting in there.