Bottom of Bowl Empty - Jabsco 37010 Electric

[Pilotpak]

The problems with my Jabsco just keep getting weirder all the time !

When I flush the head, the bottom of the bowel empties, then fills with about 1 and a half inches of water...All OK...but within an hour, the bottom of the bowl is completely dry.

This surprises me because the waste line has a loop in it that goes above the top of the head, so I'm sure water is flowing out of the waste pipe.

I've removed the shroud from the motor and can't see any obvious leaks. I'm pretty sure that the holding tank vent is not blocked.

I thought the passage of the boat might have caused a vacuum, and suction via the overboard dump line, so I switched the overboard dump "Y" valve top the "DECK" side - but problem still apparant. Problem also occurs when boat is moored.

It's only a relatively new boat, and this problem has only just started occurring.

Any ideas ?

Setup is;

Head: Jabsco 37101 Electric (new Boat)
Flush: Raw Water
Holding: 120 Litres Holding Tank
Pumpout: Overboard with diaphragm pump.
"Y" valve to Deck fitting pump.

 

[Radioactive]

If the loop is not a VENTED loop, then there is no guarantee that the water will stay in the bowl.

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Just my preference, but in a marine head there is no need for water to remain in the bowl, and I have always preferred to have it empty to avoid splashing when in motion. The "natural" state for a marine head is a dry bowl. It requires effort to maintain a small qty of water in it.

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Separate issue: Be careful about keeping the overboard dump valve open. There are two potential problems: backflow flooding the H/T and ( possibly worse ) getting inspected with a H/T dump open to the sea. They may construe this as a violation ( and if so, it is an expensive one! ). This is not true in all cases, but why tempt fate?

 

[Vic Willman]

If the loop is vented, take the vent fitting apart and clean it out, it's most likely plugged up and is no longer venting. If it isn't vented; add a vented loop fitting at the highest point of your raised loop.

The vent allows air to come into the hose after the toilet stops flushing, to stop the water in the bowl from siphoning out.