Toilet Vac U Flush pump noise

I

imspacemancraig

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Joined
May 24, 2009
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31301
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So on my toilet is this vacuum pump/flush. When you push the lever down under the toilet seat, the waste water sucks down into the holding tank. When you release, there is a ka-chunk, ka-chunking sound which I assume is the pump recharging itself for the next flush.

Now, everything seems to work as designed, but we have noticed that ka-chunking sound every so often without flushing, on its own. Any thoughts? If this is the suction recharging, could there be a leak? Or, if this isn't the recharging of the suction, what is this noise?

Really annoying when trying to sleep at night...
 
well I can tell you I have the same issue I just put mine to sleep at night. I think mine is bad duck bills it is on the project list.
 
This can be worn duck bill valves as PJ suggests or a bad seal in the bowl. Is there water in the bowl when this happens?
 
Yes, the water stays in the bowl, so not there. Forgive my ignorance, but what is a duck bill valve and where should I look for that?
 
these are the simplest instructions i have found on the web. this is on my todo list this weekend.
The duckbills valves are located at each end of the Sealand vacuum pump or vacuum generater. Simply remove one of the sanitation hoses at a time. Now unscrew the black hose nipples that the hose was attatched to. This is a two piece nipple, uncrew(seperate) them. There will be 2 buckbill valves in each end of the pump. Replace them making sure that they all face the same direction, pointing toward the holding tank or overboard valve. Thighten good and hand tight only. Replace hoses and flush 1/2 bowl of water through. It is a good idea to flush 2 or 3 bowls of water through the system in order to clean it out before disassembly.

In the case a vacuum generater you will need to remove the pump from the vacuum accumulater. Simply remove the 4, 7/16 head machine screws holding the pump on the accumulater and uncrew the white 1 1/2" screw collar from the gray 1 1/2" threaded nipple. The pump will lift off and then perform the above task.
 
look in the plumbing forum, there are a few threads on that topic. in short, if water stays in the bowl the vac leak is likely at the duckbills, there are 2 of them on the inlet of the pump and 2 on the outlet. easy to change.

next would be a leak at the head base, depending on the model you have. you should be able to hear it when everything is off on the boat

if water doens't stay in the bowl, it's either some "dirt" in teh bowl seal or a bad seal.

the newer style motors and gears from Sealand, are MUCH quieter; you can barely hear them. kits incl. motor, gear and the bellows, easy to swap but not cheap (about $300)
 
Thanks for all the help. I will take a look at it this weekend when I get up there. Just to clarify, going from memory, there looks like there is 2 parts to the setup. There is a pump that is right next to the holding tank and then a separate white container of sorts (looks like a stubby fire extinguisher) that I am guessing is where the air/suction is stored.

These duckbill valves are on either end pump then? Not on the tank looking part?

Water does stay in the bowl, so based on what you all are thinking it is the duckbills then. From the sounds of it, fairly easy to fix too.
 
you have the older system, like i do for the 3 heads on my boat: a vac tank and a separate vac pump.

indeed the DBs are on teh pump, not near the tank. unless you have 2 heads and one pump, in that case you'd have an inline DB between each tank and the Y going to the pump.

if you dont' know how old the DBs are, change them they usually last 5 to 7 years. but dont' overlook an airleak at a clamp or at the head base.
 
Only one head on my boat and doesn't seem to be a leak anywhere that I can tell. No air like sounds... I did find my manual for the pump and it looks like you all may be right on those valves... also looks fairly easy to replace on my own. Just need to get them ordered now...

Thanks for the help!
 
It is an easy fix and you can order right from boat fix or pick up at any local marine store common part. I did mine last year mine were a PIA to get to but easy to change.
 
imspacemancraig
did you stop yours from cycling?

I had to change the pump. The kit was, as Pascal said, $299. It has not cycled all day except when flushed so I have fixed mine.
now for my next project.
 
I have not had the time to fix this. Seems as the summer goes along it doesn't do it as often. Wondering if having water on the seals makes it seal better over time.

Anyhow, big problem now is that it looks like my port transmission went out on me... Poor thing is up on shore right now having the mechanic pull it out and worked on... not going to be a cheap fix...
 
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