Vacuflush not creating vacuum. Diagnostic strategy?

Loneranger

Loneranger

Well-Known Member
May 2, 2008
1,068
Knoxville TN
Boat Info
2000 SeaRay Sundancer 270
Engines
7.4l Mercruiser w/ Bravo III
I have a vacuflush system with a VG12VDC vacuum generator. Last year it worked fine. This year not so much. When the system is turned on the pump starts but never generates a vacuum. It is not that it is leaking down and turning on every so often. The pump turns on but never generates a vacuum.

Water does not leak out of the bowl. I just replaced 3 duckbill valves. The ones replaced actually looked pretty good. I replaced 2 on the out flow side and 1 on the inflow side. If my set up has a 4th valve I could not find it on my set up. Yes it was installed at the factory.

So, questions...

1) Where is the 4th duckbill valve?

2) Where do I go next in tracking down the leak? The hose between toilet and vacuum generator tank?? or The pump bellows?? How would you assess the bellows?

Thanks,

John
 
You have pictures? There is a 4th duckbill...

If your toilet is holding water, I would guess you may have a bellows pump issue... it is between the duckbill valves... the rebuild kits are not to expensive...
 
John
I don't know for sure what the trouble with your system is. I suggest you call these people and ask them the same questions you are asking here. They are extremely knowledgable and will tell you (and gladly sell you) exactly what you need to solve your problem. They'll also fax you (or direct you to) troubleshooting guides and parts diagrams.

http://www.northeastsanitation.com/
 
I do not have pictures but I can get them next week. I found an exploded parts diagram in the manual. Looks like the 4th duckbill is there in the parts diagram. I beleive the one I missed is behind a piece of PVC NPT fitting with male ends on both sides. I will check it again next week.

It seems that the diagnostic approach would be to remove the hose to the toilet and close off that intake port at the vacuum generator and see if a vacuum is generated. (this is what is accomplished with the vacuum tester that sealand sells.) Without the tester I will not be able to measure the pressure but I should be able to tell if the leak is in the vacuum generator tank/pump or in the hose/toilet side.

By the way if I have to replace the bellows they are not cheap; heck neither were 2 buck bill valves for $20.

John
 
Here's an easy thing to try:

Let the pump do it's thing for a bit, then turn it off and immediately go down into the engine room. Listen for any hissing/leaks at either the vac pump or the holding tank.

Northeast Sanitation is a great place.
 
I tried to listen for leaks however I do not think I am getting any vacuum at all to even cause hissing. I did not hear any anyways.

Thanks
John
 
I found the fourth duckbill valve. I have a vacuum generator which combines the pump and tank into one unit. To accomplish this the typical pieces that hold the duckbills on the input side are replaced by a short piece of PVC with male NPT on both ends. This allows a the pump to be connected to the tank in short run. The fourth duck bill is behind the PVC fitting. It is tough to remove without destroying the threads.

I now have the system working but I am not sure how. After replacing all of the duckbills it would still not hold a vacuum. I removed the hose coming into the vacuum generator from the toilet. I then placed a piece of vinyl over the intake and clamped it in place. Still the vacuum ran continuous. I took the pump out to the bench and disassembled it to check the status of the bellows. The bellows were fine. I cleaned and put everything back together. Reinstalled everything in the boat and now it works fine. I am not sure how I fixed it but it is fixed.

I would rather be lucky than good any day.

John
 
Sounds like you're going to need part #16 in your link above. Vacuum Switch. play with this switch when the pump is continually running. If you press it (or pull it up[?])manually and the pump shuts off, there's your problem. I had the same issue last year. It's costly but it works.
 
rondds said:
Sounds like you're going to need part #16 in your link above. Vacuum Switch. play with this switch when the pump is continually running. If you press it (or pull it up[?])manually and the pump shuts off, there's your problem. I had the same issue last year. It's costly but it works.
Click to expand...

Took the words right out of my mouth!
 
Loneranger said:
I do not have pictures but I can get them next week. I found an exploded parts diagram in the manual. Looks like the 4th duckbill is there in the parts diagram. I beleive the one I missed is behind a piece of PVC NPT fitting with male ends on both sides. I will check it again next week.

It seems that the diagnostic approach would be to remove the hose to the toilet and close off that intake port at the vacuum generator and see if a vacuum is generated. (this is what is accomplished with the vacuum tester that sealand sells.) Without the tester I will not be able to measure the pressure but I should be able to tell if the leak is in the vacuum generator tank/pump or in the hose/toilet side.

By the way if I have to replace the bellows they are not cheap; heck neither were 2 buck bill valves for $20.

John
Click to expand...

Just an FYI.

The vacuum tester that they sell will drop right into the opening in the toilet bowl without removing the toilet or any of the hoses.

The switch that Ron referred to is probably the culprit. But, now you know how the system works and you shouldn't have to replace duckbills for a couple of years provided everyone follows the rule:

If you didn't eat it first, don't put it in the marine toilet.
 
I do not believe it is the switch because it was not generating a vacuum. Yes it would not shut off, but it was not shutting off because no vacuum was generating.

I would guess that I had something causing a vacuum leak that was removed when I disassembled and cleaned everything.

John
 
Heh guys....where can I get a 1-1/2" NPT closed nipple for the vac flush? Mine's cracked and Home Depot doesn't carry this. Sealand Services? Heck....this marine plumbing is a pain in the prop! Already replaced the duck bills and now I need a nipple. (That doesn't sound right.)
 
Plumbing supply store. Check the yellow pages.
 
Anyone know where I can get the 1-1/2 inch nipple that is on the suction side? Mine is cracked and Home Depot doesn't carry 1.5 inch NPT nipples. I replaced the duck bills only to find later the crack in the nipple. Man....is this head thing...this suction thing...a pain in the prop!
 
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