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jbinbi · 24-06-2018, 11:34

I have had Jabsco manual pump toilets for almost 15 years on several boats. Usually when I pump water out and put the valve in the pump out only position and I find water in the bowl a while later it means it is time to replace the joker valve.

I just did that on a 3 year old toilet, but am finding water back in the bowl. In playing around a bit more I found that if the thru hull Y valve (direct from toilet or from holding tank) is in holding tank, I am not getting water, but if straight thru I am?

zeehag · 24-06-2018, 13:08

i find it impossible to empty completely a marine head. there is always backflow. once that stops coming back you can see how much normally is going to occur. mine is a gallon in hoses between bowl and antisiphon valve.

peghall · 24-06-2018, 14:38

If I understand correctly, there is no backflow when the y-valve is open to the tank, but there is when it's open to the thru-hull. If that is correct, does it only happen when the boat is underway? Or does it happen when the boat is sitting too?

--Peggie
"If you can't explain it to a six year old, you don't completely understand it yourself." --Albert Einstein

jbinbi · 24-06-2018, 20:31

Good question. Will have to check this over the next weekend. Can you explain your thoughts on this.

peghall · 25-06-2018, 06:13

If it only happens when the boat is underway with the overboard seacock open, you may be experiencing something known as "ram water"--water being pushed ("rammed") up the toilet discharge hose by the pressure of the hull moving through the water. The same thing often happens when sink drain seacocks are open.

If it also happens when the boat is sitting at rest, water outside the boat is simply seeking its own level INside the boat. If there's no vented loop in the toilet intake, it's not backflow...the only thing preventing sea water from flooding--and overflowing--the bowl is the wet/dry cam (which, btw, is highly failure prone in Jabsco toilets). If it is backflow, a new joker valve can block it, but only temporarily until the the toilet has had enough to use to stretch the slit open even a milimeter. If there are no vented loops in the intake and discharge lines, install them. They both need to be at least 6-8" above waterline at ANY angle of heel...which, on most sailboats, puts it 2-3' above the bowl (see photo). See the drawing in the Jabsco owners manual for the correct location of the intake vented loop.

bobgarrett · 25-06-2018, 08:30

You might need to change the bottom "flap" seal too.

jbinbi · 25-06-2018, 08:55

Thanks. very familiar with vented loop. boat is a lagoon cat. doesn't heel. but has vented loop, but don't know how high. Still not sure why having drain valve open or closed would make a difference. Toilet empties directly into holding tanks. If you open the valve, then the tank empties to ocean. Was thinking that if the vent was blocked, then maybe too much pressure in tank when pumping into it is forcing water back...I say this because after flushing, I hear a burping bubbling noise and water slowly comes back?

Some pics of the tank and the valve. It looks like the vent line is about 1 foot above the water line. The top of the tank, where the inflows are about 5' above water line. On the tank, left most valve is for pumpout, then the 2 valves on the top I think are 1 for intake, and 1 for vent. I am assuming pic showing bottom of the tank is a hose from the bottom of the tank to empty to valve (you need to zoom in, there are actually 2 hoses, 1 is coming up to tank from toilet, the other is going out to valve). Tank is behind a bulkhead and is parallel to hull, there is a cutout perpendicular for hose to lead thru to them.

Really appreciate your help!

peghall · 25-06-2018, 12:34

I'm seeing conflicting information...In your first post,you saidI found that if the thru hull Y valve (direct from toilet or from holding tank)...which indicates the y-valve allows the toilet to flush directly overboard or into the tank. Now you're saying everything goes into the tank...that the y-valve is in the TANK discharge line.

Was thinking that if the vent was blocked, then maybe too much pressure in tank when pumping into it is forcing water back...I say this because after flushing, I hear a burping bubbling noise and water slowly comes back?

And having that information a lot sooner, along with whether the water is clean or dirty, would have helped a lot...my psychic abilities are pretty limited! Burping and bubbling is a strong indication that the tank vent is blocked. Continued use of the toilet against a blocked tank vent pressurizes the system, creating backpressure that's pushing the flush back to the toilet instead of allowing it to get to the tank. Even a brand new joker valve would have a hard time blocking it...enough back pressure can even turn a joker valve inside out, resulting in an eruption in the toilet if you're lucky, or a burst tank if you're not. A toilet that's becoming harder to pump also indicates a blocked tank vent.

The vent thru-hull is the most common location for a vent blockage.

--Peggie
"If you can't explain it to a six year old, you don't completely understand it yourself." --Albert Einstein

jbinbi · 25-06-2018, 12:58

Appreciate the help. trying to post things and do work at work , sorry for not being correct. Will check the vent this weekend when back at the boat

peghall · 25-06-2018, 15:33

You may find that while the boat has sat all week, the pressure has dissipated...that there won't be any backflow for the first few flushes, misleading you into thinking everything is ok. But if the tank vent is blocked, the system will re-pressurize as the toilet is used...the toilet will start burping and bubbling again and flushes will back up again. Nor will you be able to pump or dump the tank because without a source of air (the vent) to replace contents as they're pulled out, the pumpout or overboard discharge pump will pull a vacuum preventing it from removing more than a gallon or two. So I strongly recommend that you clear the tank vent--or make absolutely certain it's not blocked (in which case, we have more work to do to figure what is causing your backup) BEFORE using the toilet again or attempting to pump out.

--Peggie
"If you can't explain it to a six year old, you don't completely understand it yourself." --Albert Einstein

Kathham · 26-06-2018, 07:20

We have a similar issue but different circumstances. We have a Jabsco electric toilet. We replaced the joker valve, hoses and thru hulls recently and cleaned the anti syphon valve. Water fills the toilet when we are stationary but is fine when we are underway. The same situation occurred before we replaced the joker valve and thru hulls. Any thoughts would be most appreciated.

peghall · 26-06-2018, 09:23

Is the water clean or dirty? Is the head forward or aft in the cabin? Is your toilet one that uses sea water or is one designed to use onboard pressurized fresh water? Are you experiencing any of the same "burping bubbling" symptoms as jbinbi?

--Peggie

peghall · 26-06-2018, 09:36

Finally had a chance to get a good look at your photos...The installation looks fine except for two things: 1. clear corrugated hose on what appears to be the pumpout line. No matter what that line is, clear hose will permeate very quickly with odor...waste can build up quickly on the walls of corrugated hose. It should be replaced with smooth walled hose that's rated for sanitation. It looks like a short piece, so it shouldn't cost you much. 2. What is the steel tube on the side (I'm guessing that's the side) of the tank?