VacuFlush—What’s normal?

Three weeks ago my VG4 pump started cycling for about 15 seconds throughout the night. “Time to perform maintenance,” I cheerfully thought. Somehow, after three complete tear downs, two maintenance kits, 2 bellows, one new pressure switch, and one set of new o-rings, I have gotten the system worse— is the pump cycles for 3-5 seconds every 2 minutes.

Is this acceptable or a harbinger of impending disaster? I was ridiculously careful during the last rebuild, almost operating in clean-room conditions. Is it possible that the seal between the top of the accumulator tank and the base goes bad? I even disconnected the input side of the accumulator and sealed it with my hand—same exact 2 minute cycling.

What is the acceptable hold time for the vacuum?

Thanks,
B

I was on the hard for five weeks.
Had full vacuum when we splashed.

My vacuum holds for weeks at a time. Before that, the system would cycle every 30 min or so. The culprit was the duck bills slightly held open by hard deposits. Replaced the duck bills, cleaned the hoses with vinegar and no problems since. It's been 2 years now, and still functioning properly.

Bill

Using plenty of fresh water while flushing is your friend.

Bill

Can we rule out the toilet as a source of vacuum leak? Have tightened all the hose clamps in the system? If yes then we can concentrate on the pump.

Thanks for the feedback. I was kind of hoping I could call this the new “normal” and cross it off my list. Sounds like more troubleshooting is in order. My last hope is that the issue is where the hose connects to the toilet base.

Possibly a red herring—could the issue be that I’m now religiously using NoFlex Digestor and that has cleaned way crudtyat was previously sealing a leak?

B

A good Vacu-flush install should hold vacuum overnight. As it ages the hold time will shorten but should hold a vacuum for several hours.

If you replaced the bellows, the o rings sometime twist or come out of the groove as you are attaching the bellows. Did you lubricate the o rings with Vaseline or some other lubricant prior to assembly?

The pressure switch o rings can also twist or come out of it's grooves. Sometimes, the pressure switch is pushed in too far and the first o ring is no longer contacting the mount.

Duck Bill's lubricated prior to install?

If after all that and still leaks, replace the pressure switch with a plastic plug or the old switch, remove the motor but leave the bellow in place, plug the inlet with an adapter that has an air fitting and pressurize tank to 5 - 10 pounds and place tank in a container of water. Do not use high pressure.

That should test the integrity of the tank and/ or locate the leak.

Does your system use the cylinder tanks or the square sided tank with pump on it?

SailorBruce said:

Thanks for the feedback. I was kind of hoping I could call this the new “normal” and cross it off my list. Sounds like more troubleshooting is in order. My last hope is that the issue is where the hose connects to the toilet base.

B

Click to expand...

If the pump continued to cycle while the VG4 inlet was plugged, as you described previously, the leak is not the hose connection.

Do you have the Vacu-flush vacuum test gauge with the rubber cone plug? Those are helpful for troubleshooting.

I have three heads and two holding tanks. The forward two empty into one tank. The aft has its own. The forward two hold vacuum forever. The aft began to cycle in the middle of the night and wake me up. Plus we had/have some smells. When I had some major work being done I asked the yard to check on the smell issue. I believe they over-tightened some of the hose clamps. Later I found that a "no longer used" hose to overboard fitting had a very slow leak. Replaced the cracked hose barb and clamps = no leaking. Then rebuilt the pump with new duck bills and bellows. No change. Then replaced the seals under the toilet. That helped a lot but still cycled. Then I replaced the accumulator tank. One of the hose fittings had also been cracked by an over clamping pressure. Now it only very slowly loses vacuum. When leaving the boat for a week I turn off the pumps. When I return and turn on pumps for the two forward heads, they don't need to pump. The aft head will pump. But, no more midnight pumping so I'm close enough. I still get smells from that area that I don't understand. None from the forward system. All hoses are max 2 years old. I'm about ready to de-install and redo with all new stuff. The smell comes from the area of the pump which is behind the drawers next to the bed. Lovely.

Three weeks ago my VG4 pump started cycling for about 15 seconds throughout the night. “Time to perform maintenance,” I cheerfully thought. Somehow, after three complete tear downs, two maintenance kits, 2 bellows, one new pressure switch, and one set of new o-rings, I have gotten the system worse— is the pump cycles for 3-5 seconds every 2 minutes.

In most cases, if the bowl is holding water, replacing the duckbill valves in the pump is all that's needed to cure the problem when the pump cycles for no reason between flushes...'cuz if that doesn't do it, there's likely an air leak in a hose connection somewhere...and there's a much easier way to test for that than using a vacuum tester gauge: squirt a LITTLE shaving cream around every connection...flush the toilet. The suction will pull the shaving cream into any hose that's leaking air...it'll just sit there on all the rest. Wipe it off the connections with a paper towel. 99% of the time that's ALL you need to do. (And Ricky...I think you'll identify the source of your odor if you do this.)

It's only necessary to replace the bellows in the pump if a clog (either a buildup of solids and TP as a result of using too little flush water or somebody flushed a wet wipe) prevents it from pumping. Nor is there any need to replace the vacuum switch unless the pump starts running longer and longer after each flush until it finally doesn't stop at all...a failed vacuum switch won't cause the pump to cycle between flushes. As for all the rest of the likely unnecessary work and EXPENSIVE parts you replaced...yep...I'm afraid you've only made the problem worse.

The VacuFlush trouble-shooting guide in the owners manuals includes just about every symptom, probable causes and cures that a V/F can develop (it's changed so little except cosmetically since Mansfield Plumbing introduced it in 1978 (Mansfield spun off their marine toilets division to SeaLand Technology in 1984) that the same trouble shooting guide works for all years, all models. I'll be glad to send you one if you'll send me PM that includes your email address...there's no way to attach anything to PM. And I'll also send you my article "VacuFlush 101" which explains how the system works.

--Peggie