Recycling Vacuflush Pump

C

cmagic99

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Joined
Feb 3, 2005
RO Number
16207
Messages
135
I have a Vacuflush issue I need help in troublehooting, please. Towards the end of last season, my pump started pumping every 5 minutes or so. Figured it was the duck bills and since it wasn't a big problem at the time, I thought I'd wait until spring to change them (give the system a chance to not smell so bad). Well, I changed all 4 duck bills and now instead of recycling every 5 minutes, it's more like every 1 to 1-1/2 minutes. What did I do wrong? What else could be causing the vacuum leak? Water appears to remain in the bowl while under vacuum. What can I do to troubleshoot this issue (besides putting in a trouble ticket and having an expert troublehoot and repair)? Thanks for any help.
 
Listen closely in the area of the duckbills for any hissing; my "gut feeling" is that the fittings weren't put back together tightly enough.

Pascal, thoughts?
 
no doubt you have an air leak somewhere. if the only thing you touched on the pump was duck bills its is most likely there. based on the age of the boat, you might also have a broken bellows that just happened to coincide with this event. look for liquid on the bellows while the unit is pumping fluid thru it.
 
i agree, if water stays in the bowl,then it'snot the bowl seal.

depending on the model, there is a seal on the base which if overtightened can leak (fairly soft rubber). shut down everything on the boat (incl. Air con) and listen near the base. if you have a leak there you will hear it.

otherwise, duck bills. likely a loose clamp. When i replace DBs, i put a little bit of liquid soap on the fitting, at the base of the DB, to make sure they don't catch and distord when tightening.
 
Thanks for the replies. I'm heading to the boat this Saturday and will do some listening. If nothing else, I'll take the duck bills back out and do as Pascal suggests with the liquid soap. I'll let you know if there's any success.
 
BTW, Would coating the base of the duck bills with petroleum jelly help or hurt any? We used to always do that to o-rings on F-4 fuel system connections to ensure a non-binding, leak-free seal (important for fighter jet fuel systems ;-) )
 
quote:
Originally posted by cmagic99

Thanks for the replies. I'm heading to the boat this Saturday and will do some listening. If nothing else, I'll take the duck bills back out and do as Pascal suggests with the liquid soap. I'll let you know if there's any success.

Click to expand...


If that doesn't cure it and you have to look for vacuum leaks elsewhere, put shaving cream around any suspected leaking area. If there is a leak there the vacuum will suck the shaving cream right in so you can spot the leak right away.
 
Great idea Capt. Bill. I had a strange problem with mine cycling when it was first installed. I can not explain why this fixed it but my new vent line for the Holding tank was kinked and the tank had no way to vent. To this day I still don't understand why that fixed it but it did. My problem started when I was doing the initialization of the new system.
Bill
 
Thanks, Capt. Bill. I was hoping there was something like that for troubleshooting. Kind of the reverse of using soapy water to spot a pressure leak (versus a vacuum leak).
 
This has been helpful I too had a problem at the end of last season. I figured it would wait for spring as soon as she is wet I'll try these ideas. I suspect I need duck bills as I have no idea how old they are.
 
Glad to be of help. But I can't take credit for the trick. I learned it from Les's ex-wife.
 
Ok, update to current issue. I removed the duck bills that I just installed, coated them with vasaline (something we did on o-rings on fuel systems in aircraft maintenance years ago), and reinstalled them. This resulted in no change to cycling time. After the initial vacuum charge (about 1 min. or so of operation), the pump comes one again about every 45 sec. for about 5-7 sec. We put our ears down near the unit to listen for a vacuum leak, but heard absolutely nothing and the environment was very quiet at the time. Went into the head and listened again around the bowl. There we heard a tick-tick sound that seemed to get a bit faster when the pump operated, although I can't guarantee that really happened. Again, water does stay in the bowl, so I'm guessing the seal further down in the bowl may be the culprit. Does it now make sense to get the rebuild kit for the bowl and redo all of those seals? Does the ticking sound I hear indicate a vacuum leak? I'm running out of options short of calling in the professionals.
 
Perhaps you should pull the head up and see if you have a leak where the hose attaches to the head. Or perhaps there is a crack in the area that the hose attaches to the head.
 
Update again. Talked with Dometic customer/technical service this week. She suggested I take a look at the switch on the vacuum generator and see if I could move it with a light touch. According to Dometic, it shouldn't move in the housing at all. I'll be going to the boat tomorrow and will see about the switch then. Capt. Bill, I've taken a look at the hoses that attach to the head and have not noticed anything out of the ordinary. I did have to tighten the clamps down a bit, but that didn't help the issue. If the switch is solid, then I'll have to head to the boat during the week and talk with Dometic at the same time I'm with the boat to do some more troubleshooting. Thanks all.
 
under a minute is a fairly rapid leak, you should hear it.

look around the fittings on the vac tank, not sure what type you have but there are a couple of fittings on the tank that can leak, incl. where the switch mounts.

there are different style of VF heads. Some have a thick but soft seal at the bottom, near the floor. it's a little fragile and can leak if overtightened. Others have a simple fitting where the hose is clamps. that can leak too if the clamps have been over tightened at some point and deformed the fitting, which isn't always barbed. you may need to pull the head up to get to the fitting, pull the hose, check the fitting and reclamp.

the tick tick sounds could be a vac leak, that's why i'm betting on the fitting/seal at the bottom.
 
That was my thought too, but I was waiting for Pascal to check in first.
 
Thanks Pascal and Vic. I found that the clamp holding the switch to the vacuum generator was very loose, but after tightening that clamp, the recycling continued as before (maybe taking about 1 min to come on, but the pump still only runs for about 6 sec to bring the vacuum back). I didn't get a change to pull the head today; will do probably one of the next two weekends. The head is a 5006 series, so there should only be 2 seals at the ball (at least that's what I see in the illustrated parts breakdown) and Dometic thinks that if either of those is leaking, the pump would run continuously and not shut down for a min. I'm going to call Dometic again on Monday and discuss some more. The switch housing doesn't move any longer, but the switch itself (the piece with the spring) moves around quite a bit (up, down, left, right) and I don't know if that's supposed to be the norm. More later.
 
Just a quick update. Took the problem to the professionals and a quick check of things showed that the o-rings on the ball shaft were leaking. They had a ball shaft kit, which they installed and all was well -- for a day, that is. The next day, when the pedal was depressed, the ball would not move and of course nothing flushed. Took the boat back to the professionals and it turns out they installed the wrong kit. I now know that I have eco-vac model and it apparently uses a different ball shaft than other models. They installed the correct kit and everything is working better than before. The system holds vacuum a lot longer than ever and even the pump sounds quieter now. I didn't even know the ball shaft was a potential place for a vacuum leak so I've learned something new. Thanks to everyone for their input.
 
Cmagic,

How did you access the ball shaft... and was it very difficult? I am still diagnosing the same problem with my VF unit so far to no avail.
 
Rowdy, I didn't do the work. I turned the job over to an authorized repair professional. I don't know if you have to remove the bowl to access the ball shaft or just the pedal and related components. Go here, http://www.sealandtechnology.com/manuals.asp, and you should be able to download the illustrated parts breakdown and manual for your unit. This might help you figure out how to get to the ball shaft. There might also be detailed R/R instructions in the ball shaft kit. Pascal might chime in, too, if he's ever replaced these seals.
 
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