Vacuflush cycling

[Skuza]

After commissioning the other day the aft toilet is cycling every 10 minutes or so. Toilet is not losing water. I checked all the clamps and pipe fittings. The Bellows are original circa '98. The last time I did the duckbills was '15.
Upon listening at the pump I don't hear any hissing but I do hear a slow gurgling coming from the pump prior and after cycling.

I might try duckbills again since theyre 5 years old and easy. PLUS no numnber 2's yet this year! Do the bellows HOLD any vacuum or just GENERATE it??
Thoughts??

 

[Jaybeaux]

My guess is that your bellows are cracked, and thus not producing sufficient vacuum and/or losing the vacuum. While you are there, might as well do bellows and duckbills. You'll be good for a while! Good luck.

 

[Air O'Nautical]

If it’s cycling...means it’s producing vacuum enough to satisfy the pressure switch when it turns off.
But, then your loosing the stored vacuum somewhere.
If your bellows is cracked you’ll not produce any vacuum at all and the pump will run forever.
My bet is simply the duckbills.

Flush as much water as possible through the system and see if it improves. I believe Noflex in the system could help but, I’ve only just started using it myself.

 

[NotHerDecision]

The above comment is correct. It’s most likely just duckbills.

 

[stephens013]

After commissioning the other day the aft toilet is cycling every 10 minutes or so. Toilet is not losing water. I checked all the clamps and pipe fittings. The Bellows are original circa '98. The last time I did the duckbills was '15.
Upon listening at the pump I don't hear any hissing but I do hear a slow gurgling coming from the pump prior and after cycling.

I might try duckbills again since theyre 5 years old and easy. PLUS no numnber 2's yet this year! Do the bellows HOLD any vacuum or just GENERATE it??
Thoughts??

I was having the same issue with my guest head unit. Changed out the duck bills (had only one duckbill on one side) and put the unit back togeather with some think silicone paste. The silicone pretty much did the trick on the main hose connecting the vacume side to the head

 

[Skuza]

Thanks I’ll give the ducks a go. As nasty as it’s supposed to be I remember it being pretty simple the one other time I did them.

 

[The Bill Collector]

For me it was Noflex Digester saved the day... Turn off the pump and pour it down the toilet and let it sit for a few days....

 

[Chris-380]

For me it was Noflex Digester saved the day... Turn off the pump and pour it down the toilet and let it sit for a few days....

Really? I switched this year, I am curious about getting the no flex do fully dissolve, or if it ever will. Concerned it will get caught up in DB or the seal around the bowl. I put the amount of no flex i need for the following weekend in a container with water and shake it up on Sunday before I leave the boat. Then Shake again Friday night, and dump into the recently pumped out system. But it never fully dissolved, even after 5 days.... I am hoping this stuff really works, any advice or suggestions is appreciated

 

[NotHerDecision]

Noflex works wonders. It only takes a tablespoon a day so it should easily dissolve. I have noticed sometimes I need to run a little extra water when I first put it in but the stuff really works well.

 

[dtfeld]

I had similar symptoms, short pump run every 10 minutes or so. There are several areas that could need attention if your loosing vacuum over time. Duck bills are a good start. However, there is a shaft with 2 o-rings on the pedal shaft that will wear over time and leak. Bowl will hold water weeks on end, but this allows a small amount of air into the vacuum below the bowl.

You can buy the kit, but if you pull and take to a local HW store, likely can source new o rings for 10 cents each.

 

[CaptRonn]

I had similar symptoms, short pump run every 10 minutes or so. There are several areas that could need attention if your loosing vacuum over time. Duck bills are a good start. However, there is a shaft with 2 o-rings on the pedal shaft that will wear over time and leak. Bowl will hold water weeks on end, but this allows a small amount of air into the vacuum below the bowl.

View attachment 85704

You can buy the kit, but if you pull and take to a local HW store, likely can source new o rings for 10 cents each.

Agreed.

Except if it's the older style with a plastic shaft, then most times removing the shaft will break it. They went to the brass shaft for a reason. If anyone is considering doing this, I highly suggest buying the kit and do it right.

And a lot of air will leak by those orings if they are worn.

 

[Skuza]

Update
Bought the ducks and did it. Had them installed in about 15mins. Put it back together and exactly the same issue. Looking and listening some more I heard a faint hiss at the elbow that dumps into the vacuum tank. Seems like the stiffness of the waste hose was putting pressure on this elbow as it passes through a thick o-ring and causing the leak. The store had the o ring (1-1/2”) and I installed. Seemed to still be slightly hissing so I cut a Zip tie holding the waste hose which seemed to release some of the torque on the elbow as it passes through the o ring. Maybe some silicone grease would further help. Maybe the new o ring will take a seat after a day or so. I hate that I wasted $60 on the duck bills but at least I know they are good. The one’s I took out had a little gap at the sealing lip which I figured was the problem.
Gonna keep an ear on it.