Vacu Flush Woes

[Midnightsun]

Started firing up the systems on the boat only to find the forward toilet would not build a vacuum. I push the flush pedal, the bowl opens, water flows but just builds up as there is no vacuum in the line. I hear the chug a chug sound so the unit is trying to build a vacuum but just goes on and on. I let it run like this for a good 15 minutes, shut her down and tried again for a good 15 minutes but no joy. Can someone point me in the right direction before I rip everything apart unnecessarily.

Additional info: Worked perfectly fine last fall before winter layup and never an issue. No lines were disconnected or valves closed for winter layup. My procedure is to make sure the holding tank is as empty as possible and since the toilet draws water from the potable water system I simply flush the toilets while connected up to the "pink stuff" until I get a good stream of pink. Flush once and repeat a second time.

[mjk1040]

If you can't find no apparent vacuum leak or if you are not building vacuum, then I would be looking at the pump it's self. I believe they are a diaphragm type vacuum pump. Somewhere I saw a demo video on taking this pump apart and replacing the diaphragm. Of course it is most likely located right in the PITA location! Hope this is your issue and ur up and running soon. Good Luck!

[Midnightsun]

No they are a bellows pump. I am hoping there is something kinda easy and obvious other wise I think it could be a bad bellows. The toilet is a 5000 series and it does have the newer Whisper Quiet vacuum pump. Just find it a little too coincidental this happens all of a sudden after winter layup.

98% sure this is what I have. https://www.dometic.com/en-ca/ca/produc ... g4-_-25287

Found this which basically shows me what could need replacing. After watching this I now think it could be some worn duck bill valves that maybe did not like the pink stuff.

Exploded parts view diagram. https://seacoastservices.com/jw-series- ... vg4-parts/

[Viper]

Is the bowl holding water? If not, the bowl seal is the leak. The other regular maintenance item is the duckbill valves (check valves). There are two on each side of the pump in the fittings that attach to the pump. If their lips stay open due to age or debris, you'll never build up a vacuum. Make note of the direction they are facing when you pull them out, it's important that they face that way. While the pump's components can eventually fail, it's a pretty robust design and has always been my last resort of the diagnostic process. As a result, I've only had to replace very few actual pump components. It's usually something else at fault like the items mentioned above or a leaking fitting.

[Midnightsun]

Thanks for reply, much appreciated. As mentioned the water is building up in the bowl every time I flush so yes the bowl is holding water and obviously no vacuum happening as pump just keeps on running. No blockage either.

Did order 2 sets of duckbill valves https://www.marinesan.com/2-Duckbill-VG ... 311581.htm as they probably need attention regardless if they are not the problem. Pretty sure these are the originals at 10 years old.

[bud37]

Source of the post Pretty sure these are the originals at 10 years old.

I think you may have found the problem....good luck with it.

[Midnightsun]

It's a shitty job but somebody has to do it.

[CaptBob]

My vacuum generator is located where I just cannot get to it. It's a shame. My wife however can. A couple of years ago, she had to go in and replace the duck bills, bellows, and since she was there we replaced the pressure switch and did the quiet pump upgrade. While I did put up with a fair (well, maybe more than fair) amount of grief from her, the upside is she is adamant about instructing new guests ('specially those of the female variety that have troubles estimating the amount of toilet paper needed per episode) on the care and feeding of a marine toilet.

What started this problem was a broken bellows. It just ran and ran without building a vacuum. I was however impressed that the duckbills were still doing their job after seeing their condition after removal.

[Midnightsun]

Hmmm, maybe I should order a bellows just in case. I do have 2 toilets so eventually I will be needing to replace one even if it is not the actual problem just right now.

[Viper]

The components are readily available and if you had just one head, I'd say go for the spare parts including the quiet motor upgrade but a failure will only take out one head for the weekend, leaving you with the other still operational. You should carry spare duckbills and bowl seals though. The bowl ball, fresh water valve, and pressure switch seldom fail but everything breaks eventually. You should also consider that Dometic is always improving component designs so by the time you go to use one of those expensive spare parts, there might be a newer upgrade available.