unable to pump into holding tank

[Johnnie Cake]

Peggy,
I am unable to pump into the holding tank on my 87 Hunter 40. I have two heads and holding tanks ( one works just fine) so last time I went to pump out I first tried to put water into the tank at the deck cap. It only took a little before it was full but when I tried to pump out very little came out. It pumps fine overboard. I see in your post a lot of problems are the vent. Do you think this is the case.
Thanks
Ed

 

[Bob V]

Had the same problem on my C42

brand new boat. One head worked as expected the other would not pump out from the deck fitting. It turns out the hoses were reversed at the factory. Mine was not the only boat that went out that way. It was hard to see the problem because both hoses went through the bulkhead in the same place.

Trace your lines from deck fitting to bottom of tank (hopefully) or maybe top of tank as mine was installed.

My hull number is 1003 so I would have thought that they would be pretty good at hooking it up right by now but it turns out a new guy on the line was clueless and it slipped by quality control because it was hard to see.

 

[Peggie Hall HeadMistress]

My money is on a blocked tank vent...

'Cuz it's a 20 yr old boat. If the plumbing were reversed at the factory, I'm pretty sure that would have been discovered and fixed a long time ago.

I think you'll find all the information you need about how to clear the vent and keep it clear in several recent posts on the subject in this forum. If you still have questions after reading through 'em, I'll be glad to answer 'em.

 

[jdhohmann]

I would check for a directional valve, Our Hunter 40 has a directional valve that works like a check valve, you have to turn the handle in the proper direction so that you can put your head flow to the Holding tank, and then turn the handle the opposite direction to allow flow out of the holding tank!!!!!

 

[Peggie Hall HeadMistress]

You're saying that the head discharge line and the tank pumpout line are the same line???

If so, that's NOT how it should be plumbed! And, if so, that needs to be corrected!

But I doubt that it is. I'd bet money that you also have a blocked tank vent.

The only purpose for any y-valve in the line from the toilet is to provide a choice between flushing into the tank or flushing directly overboard...it should have nothing to do with emptying the tank. If the tank is plumbed to allow dumping it at sea, the tank overboard discharge line prob'ly uses the same thru-hull.

So yes, the y-valve would have to be open to the tank to move waste from the toilet into the tank...but it should have nothing to do with dumping the tank or pumping it out unless you also have a blocked tank vent...in which case, the suction from the onboard discharge pump or marina pumpout would pull air from wherever it can...in your case, the toilet. The joker valve in the toilet discharge is prob'ly so worn out that the pumpout can pull in enough air through it.

But the tank vent should also provide an escape route for air displaced by incoming waste...if the air can't out, the tank will become pressurized, at the very least causing waste to back up into the toilet...worst case, a burst tank.

So your tank vent AND your toilet are in SERIOUS need of maintenance--and MAYBE re-plumbing...'cuz since holding tanks are not requred in your waters, it is possible that a PO installed your tank incorrectly. If you'd like to email me, I'll be glad to help you sort out what you really have and what needs to be done to make it right.

Meanwhile, I suggest that both y'all check out the link in my signature...it goes to a comprehensive "marine toilets and holding tanks 101" manual that will teach you how to install, operate and maintain your systems correctly to prevent 99% of problems.

 

[C lectric]

A plugged seawater intake can also prevent clearing of the toilet.