back pressure

Peggie Hall HeadMistress · Jun 20, 2010

What "few things" did you try...

To unblock the vent? 'Cuz it's obvious you still have a blockage somewhere...let's start with the easiest one first. So tell me exactly what you did...

zeehag · Jun 20, 2010

could you have pulled up an octopus or other sealife into the intake ?? is what happens to mine---i put vinegar in the bowl for the day and wait --sometmes takes days....
when the critter is gone--dead and gone--i can again flush .....i like the idea of a screen plate over the intake for water....until he is dead i have to use a bucket to flush....on my friends boat we went sailing on for a year, the hosing to the holding tank would clog--we had to let vinegar sit in the hoses until the salt blocks( i hope they were salt) dissolved and hosing was again of proper internal diameter....makes it hard to pump.....

Peggie Hall HeadMistress · Jun 20, 2010

Sounds like tank vent is clear...

To clean out the vent thru-hull, use a screwdriver blade or whatever works to ream it out. But from your description, it sounds like the vent is clear.

So next thing to look at is the head discharge--the joker valve and the the head discharge hose for a blockage that's most likely to be sea water mineral buildup or MAYBE something you've sucked up that somehow made it through the pump and has gotten caught in the joker valve....you definitely have a blockage somewhere downstream of the toilet. So first check for a kink the head discharge line...then remove the discharge fitting and check that.

Next question: have you recently had landlubber guests aboard? 90% of marine toilet problems are caused by guests who flush something the system can't handle. So it's VERY important to tell them that NOTHING they haven't eaten first can go into the toilet except for the TP that you've provided.

Zeehag, letting vinegar sit in the bowl will destroy the joker valve...when soft rubber is left to sit and soak in vinegar, it swells up and distorts. Nothing you put in the bowl will do anything for something caught in the intake anyway...'cuz bowl contents don't (thank heaven!) recirculate through the intake. It was time, not the vinegar, that dissolved any critters that came in through the intake. If that's a common problem in your waters, a screen or strainer in the intake is definitely a good idea. But undiluted distilled white vinegar does dissolve mineral buildup in the discharge line...and a cupful of it flushed once a week when the toilet won't be used again for several hours will prevent buildup. Just be sure to flush it all the way through the system.

However, his problem isn't in the intake...it's DOWNstream of the toilet, creating back pressure. We'll find it...

zeehag · Jun 20, 2010

Peggie Hall-HeadMistress said:
To clean out the vent thru-hull, use a screwdriver blade or whatever works to ream it out. But from your description, it sounds like the vent is clear.

So next thing to look at is the head discharge--the joker valve and the the head discharge hose for a blockage that's most likely to be sea water mineral buildup or MAYBE something you've sucked up that somehow made it through the pump and has gotten caught in the joker valve....you definitely have a blockage somewhere downstream of the toilet. So first check for a kink the head discharge line...then remove the discharge fitting and check that.

Next question: have you recently had landlubber guests aboard? 90% of marine toilet problems are caused by guests who flush something the system can't handle. So it's VERY important to tell them that NOTHING they haven't eaten first can go into the toilet except for the TP that you've provided.

Zeehag, letting vinegar sit in the bowl will destroy the joker valve...when soft rubber is left to sit and soak in vinegar, it swells up and distorts. Nothing you put in the bowl will do anything for something caught in the intake anyway...'cuz bowl contents don't (thank heaven!) recirculate through the intake. It was time, not the vinegar, that dissolved any critters that came in through the intake. If that's a common problem in your waters, a screen or strainer in the intake is definitely a good idea. But undiluted distilled white vinegar does dissolve mineral buildup in the discharge line...and a cupful of it flushed once a week when the toilet won't be used again for several hours will prevent buildup. Just be sure to flush it all the way through the system.

However, his problem isn't in the intake...it's DOWNstream of the toilet, creating back pressure. We'll find it...

ahaa--ok --ty---i also flush oil( olive is what i always have-) after the vinegar---sometimes helps----the vinegar is always in sea water---not quite full strength--

Peggie Hall HeadMistress · Jun 20, 2010

That prob'ly won't work

Unless the tank is empty. 'Cuz if there's anything in the tank, opening the pumpout fitting doesn't let much air out of the tank when the toilet is flushed because the tank discharge is at the bottom of the tank...the flush would have to lift 8.333 lbs for every gallon of waste in the tank to let any air escape. So it would only work if the tank were seriously pressurized...and then it would prob'ly work TOO well...THAR SHE BLOWS! So if you want to try that, first see what happens when you pump out. You should have a pretty good idea of how much is in the tank...Pay VERY close attention to whether the pumpout removes that much or stops pulling anything out after only about a gallon or two. If there's nothing much in the tank, fill it at least half full with water.

Unlikely that you could have both a clogged vent AND a clog in the discharge line...but not impossible.

Paul Mermelstein · Jun 20, 2010

Berndahle said:
But I still have the back pressure. Plus sometimes after pumping out water in the head, it bubbles back up and fills up with some water again. ... I think it would be unlikely that I had a clogged vent AND a clogged hose.

One time when my tank vent was clogged and I had back pressure on the pump handle, I found that my my pumping action had turned the joker valve inside out. Yep, that's right: inside out. So after I cleared the tank vent I had the symptoms you described of continued back pressure and refilled bowl. After I replaced the joker, the remaining problems went away.

Mike8245 · Jun 21, 2010

I have a 2003 356, very similar to yours. Just last month I too had bubbling in the head after flushing, but I too could smell the odor outside so said to myself- I need to get a new joker valve. Before I got around to ordering one I did a pump out. To my surprise when I was done I was hearing a slow hissing sound for a minute or so. My problem was an "almost clogged" vent line due to those dang dirt dobber bees. I totally understand what you mean about trying to remove that vent line- no dice it is in a bad bad spot where it is attached to the hull, the tank end is doable but then all the flushings go in the area around the tank. My fix was to flush the vent line a hose a few times and problem solved. I know Peggy does not like the screen that ussually comes in those fitting, but it will keep those dang bees out. I thought mine had a screen but if it did it has come up missing somehow. Do the easy thing and flush the vent line hard a few times and see what happens on yours. Best of luck, Mike

Head Master18695 · Jun 21, 2010

The question was asked, what is the purpose of the joker valve?

In a manual head, it's purpose is twofold: 1) to act as a check valve to stop unwanted water (and other stuff) from backing up into the toilet bowl if you have restricted hoses or a partial clog downstream of the toilet, and 2) more importantly, it works in concert with the flapper valve at the base of the toilet's pump, to move the bowl contents out of the toilet and off to your holding tank. On the upstroke of the pump, a partial vacuum is created which causes the joker valve to close tightly, and the flapper valve to open, which draws part of the bowl's contents into the botttom half of the pump. Then on the downstroke of the pump, the flapper valve slams shut and the contents of the bottom half of the pump (that were just drawn from the bowl) are forced out the rear of the pump, through the joker valve, and off to your holding tank.

Peggie Hall HeadMistress · Jul 2, 2010

Tank discharge FITTING is at the top of the tank...but...

There has to a pickup tube inside the tank to the bottom...if it's not there, the tank could not be pumped out...the pumpout would only pull in air via the vent...it couldn't remove any tank contents. So opening the deck pumpout fitting wouldn't vent the tank whether the discharge fitting is at the bottom of the tank or on the top. However, since you were able to pump out the tank with no problem, that means the vent is no longer blocked.

Or maybe not...'cuz if the vent IS blocked, the pumpout will be able to pull out a gallon or two, then nothing...misleading you into believing that it has succeeded in emptying the tank. But if you're absolutely certain that the tank IS empty...

Yes, you prob'ly do have a blockage in the head discharge line TO the tank. Now that the tank is empty, you should be able to disconnect that hose from the tank inlet fitting and the toilet without risk of a major spill...take it out of the boat onto the dock and blast it out with a hose...then put it back.

There's not much more anyone can do for you from here unless it's someone who has a lot more psychic power than I do...trouble-shooting it has to be hands on from here. Let us know what you find!

Peggie Hall HeadMistress · Jul 4, 2010

Try muriatic acid

It's available from any hardware store and will dissolve mineral buildup, TP and just about anything else except wet wipes tampons or condoms without harm to the toilet, hoses or tank.

Follow the directions for handling VERY carefully!

Have you disconnected the discharge hose from the toilet to see what it looks like inside? Check out this recent thread: http://forums.sbo.sailboatowners.com/showthread.php?t=120202

Peggie Hall HeadMistress · Jul 28, 2010

It really does help to get theWHOLE story...

I think you've actually had THREE separate problems... Because your tank was bulged, I'm still pretty sure that one of 'em was blocked tank vent...if you're sure the vent is now clear, I think you've solved one of 'em.

Berndahle said:
I've also discovered that the resistance when pumping the bowl dry mostly goes away when I push a little harder on the little lever that switches between dry and wet.

You managed to leave that part out till now :bang: That tells me that you prob'ly DON'T have a clog in the head discharge line after all ...that the wet/dry cam in the toilet pump has failed...ia VERY common problem in Jabsco toilets made in the last 8-10 years. It hangs, creating what feels like back pressure. The cure: replace the wet/dry cam (it's NOT a part that's included in the rebuild kit, btw)...or the toilet with one that doesn't have problems like this!

Berndahle said:
Also, I've noticed a very sulphuric smell when I pump water into the bowl the first time I come back to the boat, and the water is pretty dark and dirty. That goes away after a few pumps..

And THAT tells me that you've sucked up some animal or vegetable sea life that's died and is decaying in your intake line, pump and/or channel in the rim of the bowl. The cure for that one is fairly easy: disconnect the head intake line from the intake thru-hull (it would prob'ly be a good idea to close the seacock first)...stick it into a bucketful of clean FRESH WATER to which you've added a quart of distilled white vinegar...NOT cider vinegar, WHITE vinegar. Flush the whole bucketful through the toilet. That should clean it out. Follow that with another gallon of clean water to which you've added about 4 oz. of Raritan "C.P. Cleans Potties"...don't use the toilet again for 24 hours. That should solve the intake problem.

The odor out the tank vent when you flush is yet another problem that needs to be addressed. There's been enough discussion in this forum on that subject that I shouldn't have to spend another hour typing what you need to do to solve that one.

Berndahle said:
I'm not sure exactly what the inside of the pump mechanism looks like yet but I'm starting to get the feeling that there may be an issue with it or the flapper valve inside.

I'm starting to get the feeling that you need to start keeping up with the PREVENTIVE maintenance needed to keep your system working reliably and trouble free and odor free. You might want to check out the link in my signature...it goes to a comprehensive "marine toilets and holding tanks 101" manual that'll teach you how to maintain your system.