Head problems

higgs

.
Aug 24, 2005
3,627
Nassau 34 Olcott, NY
My Groco head keeps back filling from the holding tank. I have replaced the joker valve numerous times. I also have tightened the flange behind the valve tight, replaced it and tightened loosely and I still get the back filling. This is a high quality Groco head. Any ideas before I buy a new head.
 
Jan 11, 2014
11,323
Sabre 362 113 Fair Haven, NY
Have you cleaned out the holding tank vent? This sounds like a vent problem, perhaps compounded by hoses that are plugged or have restricted flow.
 
Dec 2, 1997
8,709
- - LIttle Rock
Unless the tank is full to overflowing, there's no way that waste IN the tank can back up into the toilet 'cuz the inlet fitting is on the top of the tank and tank contents can't jump up into it. The ONLY exception would be waste spilling into the toilet discharge hose when the boat is heeled...but that can only happen when the tank is at least half full and only while the boat is heeled over pretty hard. So what's running back can only be waste in the toilet discharge line that back pressure is preventing from making into the toilet. And, as others have already suggested, the most likely culprit is a blocked tank vent.
Tank vents have 2 main functions: 1. To provide an escape for air displaced by incoming contents... and 2. Provide a source of air to replace contents as they're pulled out by a pumpout or overboard discharge pump.
Do NOT use the toilet again or try to pump out or dump the tank until you've cleared the vent. Without a source of air to replace contents as they're being sucked out of the tank, the pump will pull a vacuum that'll prevent it from pulling out more than a gallon or two. A particularly strong pumpout can even implode a tank.

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 by cleaning out the thru-hull...use a screwdriver blade, ice pick--whatever works. If that doesn't result in a spew out the vent, you'll need to relieve the pressure before removing the vent line from the tank to clean them out...so open the deck pumpout fitting VERY CAREFULLY with a hose at the ready. Be sure you're UPwind of it! Scrape out that end of the vent line and the vent fitting on the tank...replace the vent line.

You'd know all this if you'd read my book! (see link in my signature, just click on the title) The title (my publisher's idea) is a bit misleading...'cuz although it does deal with every source of odor on a boat and how to cure, or better yet PREVENT 'em, it's actually a comprehensive "marine toilets and sanitation systems 101" manual that explains the laws, describes all the types of systems and how they work, and will help you learn how to operate and maintain your system to prevent 99% of problems instead of having to cure 'em. 'Cuz you get to do any preventive maintenance on your terms when it's convenient...the need to cure a problem never happens when it is! And I'm always glad to answer any questions it doesn't.

--Peggie
 
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Apr 8, 2010
1,942
Ericson Yachts Olson 34 28400 Portland OR
Listen to Peggy.
:)
And, then, rebuild the hose scheme for your marine head. Icky work, but once you actually replace all the old hoses and (sometimes) reformat the hose and valve layout, it will: 1) work like it should, and 2) be understandable to you in case any followup work is needed.
"Been there, done that, and went thru a number of vinyl gloves and a quart of bleach/cleaner. " That was over a decade ago, and no smells or problems since.
We used that project as a further reason to have Ronco make us a larger tank and also relocate the tank hose connections to the top using dip tubes. All new hose, valves, and parts. Since we had the hand pump option for offshore tank emptying, that pump was replaced too.
I have pix and lamentations in a thread over on the Ericson site, but your boat is probably 90% different in hose routing, etc.
 
Dec 2, 1997
8,709
- - LIttle Rock
And, then, rebuild the hose scheme for your marine head. Icky work...
It doesn't have to be if you do the necessary prep first: flush the whole system very thoroughly with plenty of clean fresh water (use a bucket!? before you disconnect anything. Put a trash bag or disposable pan under each connection to catch any drips. Warming hoses a little (I always used a blow dryer) makes 'em a LOT easier to get off their fittings and the new ones on...lubricate the fitting and inside of the new hose with dish washing liquid or better yet, a little K-Y which is waaay slipperier and water soluble so it dries out. It's often much easier to pull new hoses through as you pull the old hose out. Put both onto a male-male "hose mender" fitting butted tightly together. Use PVC cement, gorilla glue, whatever you have to secure the hoses on the fitting...hose clamps can get hung up, duct tape won't hold if you have to pull hard.

Rerouting the toilet discharge hose, relocating the vent fitting on the tank (a fairly easy job using a Uniseal UNISEAL ), and replacing the "vent" thru-hull with an open bulkhead thru-hull will prevent spills out the vent, allow a lot more oxygen in the tank, and also let you prevent future vent blockages by giving you a vent thru-hull you can stick a hose nozzle against and back flush the vent line.

--Peggie
 
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Apr 8, 2011
768
Hunter 40 Deale, MD
So I have a clogged holding tank vent, despite spraying it fairly regularly. Before I start prying, twisting, and any other manner of stupid things, does anyone know the best way to remove this vent cover so I can get a hose and maybe snake straight into the vent hose? Boat is a 2009 Hunter 36, and my vent LOOKS like this one from the outside, but I have no way of knowing exactly which brand it is.

upload_2019-6-24_8-34-3.png
 
Dec 2, 1997
8,709
- - LIttle Rock
It's not a vent COVER. That type of thru-hull is designed to keep sea water out of water and fuel tanks...boat builders use 'em on waste tanks too 'cuz it costs 'em less to buy the same on in bulk, whether it's the right kind for waste vent or not..it's not! Unlikely that you need to get a snake into it, 'cuz the vent LINE is rarely blocked. 99% of blockages occur in only two place: the thru-hull and the other end of the vent line--that end of the hose and the vent fitting on the tank (very common on sailboats due to waste spilling in the vent when the boat is heeled).
It's possible to clean out most thru-hulls using a screwdriver blade, ice pick--whatever works. However, looking at your photo of the vent thru-hull, I'm not sure that's possible...so you may have to remove it (which I'd strongly recommend you do anyway and replace it with a standard "bulkhead" or "mushroom" thru-hull that'll do two things: allow a LOT more air exchange with the gasses in the tank and let you prevent future blockages by sticking a hose nozzle against it and back flushing the vent line every time you wash the boat and/or pump out.
It looks like there's a hex nut on it...it would be tight against the INSIDE of the hull. So to remove it, disconnect the hose (easier if you WARM it just a bit...I always used a blow dryer...use heat gun if you really know what you're doing with one 'cuz too much heat can damage the hose) and loosen the nut.
Oh btw...I'd open the pumpout cap to relieve any pressure in the tank before removing the vent line!
--Peggie
 
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Apr 8, 2011
768
Hunter 40 Deale, MD
It's not a vent COVER. That type of thru-hull is designed to keep sea water out of water and fuel tanks...boat builders use 'em on waste tanks too 'cuz it costs 'em less to buy the same on in bulk, whether it's the right kind for waste vent or not..it's not! Unlikely that you need to get a snake into it, 'cuz the vent LINE is rarely blocked. 99% of blockages occur in only two place: the thru-hull and the other end of the vent line--that end of the hose and the vent fitting on the tank (very common on sailboats due to waste spilling in the vent when the boat is heeled).
It's possible to clean out most thru-hulls using a screwdriver blade, ice pick--whatever works. However, looking at your photo of the vent thru-hull, I'm not sure that's possible...so you may have to remove it (which I'd strongly recommend you do anyway and replace it with a standard "bulkhead" or "mushroom" thru-hull that'll do two things: allow a LOT more air exchange with the gasses in the tank and let you prevent future blockages by sticking a hose nozzle against it and back flushing the vent line every time you wash the boat and/or pump out.
It looks like there's a hex nut on it...it would be tight against the INSIDE of the hull. So to remove it, disconnect the hose (easier if you WARM it just a bit...I always used a blow dryer...use heat gun if you really know what you're doing with one 'cuz too much heat can damage the hose) and loosen the nut.
Oh btw...I'd open the pumpout cap to relieve any pressure in the tank before removing the vent line!
--Peggie
Peggie:

THANKS, very much, for the reply. I'm wincing because the thru hull fitting is unreachable from inside the boat. I'm not sure that I can even see it without an endoscope. I think I can - just barely - get to the vent hose where it joins the tank, but even if I can I'm not sure I can do much with it beyond snap a photo. My guess is Hunter did all that work before putting the interior into the boat. I'd certainly love to take your advice, but am unsure about how to go about the work involved given the access?

Any suggestions? Have any other Hunter owners done this in a 356 or 36 (waste tank in starboard aft lazarette)?
 
Jan 22, 2008
8,050
Beneteau 323 Annapolis MD
...Any suggestions?...)?
How about use a Dremel tool to cut away the vent head from outside the hull- like drilling out a rivet? Sounds like you should be able to cut away an interior liner, or easier, move the thruhull location to where you can install it???
 
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Oct 22, 2014
352
Pearson P303 #221 RockPort Maine
You got it Ron! However, I had one to like that one and wanted to snake it out to the tank. I decided to drill a hole into the cap 1/4in. and found it worked to snake the tubing as is. didn't have to remove or relocate vent just keep it cleaned out every now and then. Capt. Rob
 
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Apr 8, 2011
768
Hunter 40 Deale, MD
StargazerP303/Ron20324:

Excellent ideas. I may try the drill and snake idea first. Will stay tuned for others to pitch in as well. THANKS!
 
Dec 2, 1997
8,709
- - LIttle Rock
Weeelll...not quite that excellent after all. A 1/4" tube in it will leave you with a vent that's less than half the diameter of a vent that's already too small to allow enough air exchange, and has an even greater likelihood of clogging due to heeling.
I'd leave that thru-hull alone and run a new 1" vent line to a new thru-hull in an accessible location.
--Peggie
 
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Apr 8, 2011
768
Hunter 40 Deale, MD
Weeelll...not quite that excellent after all. A 1/4" tube in it will leave you with a vent that's less than half the diameter of a vent that's already too small to allow enough air exchange, and has an even greater likelihood of clogging due to heeling.
I'd leave that thru-hull alone and run a new 1" vent line to a new thru-hull in an accessible location.
--Peggie
Oh, I plan on leaving the larger vent in place and just roto-rooting it through the 1/4" hole drilled in the face. And using that hole to regularly make sure the existing vent line is clear. I found a 3/16" spring steel drain and trap cleaner that should thread nicely into the hole if the hose, or vinegar soak + hose doesn't clear it.

IF I can figure out how to "run a new 1" vent line to a new thru-hull in an accessible location", disconnecting the old vent line and replacing with the new proper vent and vent line, I'll fill in the current cover behind what you can visually see in the old cover (maybe some 4200) to keep what's outside, out.