Need help from 330 & Marlin owners with vacuflush issue

[jip40]

About 2 years ago I had the vacuflush system serviced with new duck bill valves, etc.

Everything was fine for first year and then it seemed to develop a leak with a vacuum seal. It started out where the vacuum pump would come on maybe for two or three cycles every hour or so. Now it's gotten to the point of coming on about every 20 minutes and running for 10-14 cycles.

Before I get in there and start pulling the wrong things apart, I wanted to check to see if anyone else has had the same issue and what the solution was.

Looking forward to some helpful advice

 

[wspitler]

Could be the duck bill valves again, but an easy check is after you have flushed and the vacuum tank is under vacuum, fill the toilet about half way with water (after flushing a few times to get any debris out of the seal). Watch to see if the water leaks down over time. If the water leaks down, the toilet bowl seal is bad, allowing it to lose vacuum. If the seal is bad, before you replace it, try cleaning the mating surface and coating it with some silicone grease. Worked once for me. Another reason could be debris in the duck bill valves. Run several gallons of water through the system and it may allow the valves to reseal. I had the exact problem last year and changed the duck bill valves. Now it will hold a vacuum for days without running. Otherwise, it is either a bad vacuum sensor (not likely) or a leak in the tank/plumbing. Good Luck!

 

[journeyman]

an easy check is after you have flushed and the vacuum tank is under vacuum, fill the toilet about half way with water (after flushing a few times to get any debris out of the seal). Watch to see if the water leaks down over time. If the water leaks down, the toilet bowl seal is bad, allowing it to lose vacuum.

I believe this is starting to happen to mine. At this point, If I "jiggle the handle" it seats but I'm sure it's a matter of time.

 

[DennisG01]

I don't own a 330 or Marlin, but keep in mind that anyone with knowledge of a VF system can help - it does not care what boat it is in as it's essentially a totally separate system from the boat.

As Spitler mentioned, start with the toilet and whether or not you lose water - that's easy to do. Then follow the hoses best you can - especially at the vacuum tank- and listen (you might get lucky!) for escaping air. Fittings, and where they plug into the tank, are another area to look at. The pressure switch is another possible culprit - if it's over 10 years old, I'd probably just replace it.

Do you have vacuum tank that is mounted separately than the holding tank? Or is the vac tank mounted directly to the holding tank?

 

[HMBJack]

Since we're on the subject, let me ask:

"The pressure switch is another possible culprit - if it's over 10 years old, I'd probably just replace it."

Curious if you happen to know where this switch is this located? And, what are the symptoms of a bad switch? I have a system where the vacuum tank sits on top of the holding tank (2006 330 Express).

On mine - I get pressure but it's not as much as it used to produce. Not sure why.
I don't seem to have a leak as I never hear the Vacuum pump come on repeatedly - I just get about 50% of the pressure I used to have.

Any suggestions?

 

[Fishtales]

Not being an expert on crappers...
I clean the seal that the ball at the bottom of the bowl sits on to hold the water in the bowl often. Seems to keep the head working properly. I have no idea what the parts are called....

 

[DennisG01]

Jack, your vac switch should be located at the corner of the vac tank under a white, plastic, protective cover. If the spring is shot (weak), then it won't allow full pressure to be developed. Meaning, it will turn off the motor before full pressure is made. This "could" be your issue, but it's also very possible that you have a blockage somewhere. I've never done it, but there is what appears to be a little adjuster wheel on top of the spring - I "assume" one could dial in more or less pressure with that. But I'm not sure how reliable that is as a "fix". And I wouldn't mess with it without having a vac gauge hooked up to the system.

Jip, if you find the leak is where the vac switch fits into the tank, then you may be able to simply replace the o-rings. But the switch part of the switch typically craps out (see what I did there!?) after a while, hence the 10-year-ish lifespan... although some last longer and some less. I'd also pull the vac pump apart and check things out/clean it out. I doubt you have a torn bellows as that would mean the pump would most likely NEVER shut off, but it's probably good to check things out and make sure the o-rings are good. And, as mentioned, the duckbills are the most common cause for your issue - a very likely scenario could be that someone flushed something they weren't supposed to and it damaged the duckbills, and the damage has gotten progressively worse. Of course, I'm just spitballin' here - but it is at least a logical explanation. You've got an air leak somewhere - just got to find it.

And, for the record, I'm no expert either! Just someone who has had to get his hands dirty a few times...

 

[jip40]

an easy check is after you have flushed and the vacuum tank is under vacuum, fill the toilet about half way with water (after flushing a few times to get any debris out of the seal). Watch to see if the water leaks down over time. If the water leaks down, the toilet bowl seal is bad, allowing it to lose vacuum.

The water level in the bowl is not draining out and I periodically clean the seal as I have had the draining issue in the past.

As Spitler mentioned, start with the toilet and whether or not you lose water - that's easy to do. Then follow the hoses best you can - especially at the vacuum tank- and listen (you might get lucky!) for escaping air. Fittings, and where they plug into the tank, are another area to look at. The pressure switch is another possible culprit - if it's over 10 years old, I'd probably just replace it.

Do you have vacuum tank that is mounted separately than the holding tank? Or is the vac tank mounted directly to the holding tank?

I don't know where the pressure switch is located but with the manual & looking at the system I should be able to find it. I don't know where the vacuum tank is located - it's been a couple of years since I had worked on it. Unfortunately, it will be about 3 weeks before I get back down to the boat.

Jip, if you find the leak is where the vac switch fits into the tank, then you may be able to simply replace the o-rings. But the switch part of the switch typically craps out (see what I did there!?) after a while, hence the 10-year-ish lifespan... although some last longer and some less. I'd also pull the vac pump apart and check things out/clean it out. I doubt you have a torn bellows as that would mean the pump would most likely NEVER shut off, but it's probably good to check things out and make sure the o-rings are good. And, as mentioned, the duckbills are the most common cause for your issue - a very likely scenario could be that someone flushed something they weren't supposed to and it damaged the duckbills, and the damage has gotten progressively worse. Of course, I'm just spitballin' here - but it is at least a logical explanation. You've got an air leak somewhere - just got to find it.

Dennis - thanks for the advice, I will follow it once I get back down to the boat

 

[HMBJack]

Thank you very much for the input Dennis.

I'll check out that spring pressure. That could be my issue.

 

[journeyman]

your vac switch should be located at the corner of the vac tank under a white, plastic, protective cover.

I know this pic is a little distorted, but it's all I got.

So the vaccuum switch is in/under the white box on the left side of my tank?

Just for clarity, my Vac tank and holding tank are separate.

 

[DennisG01]

Jack, let's "hope" the switch is the issue. Odds are better on the issue being a clog, but the vac switch is certainly the easier thing to work on/replace!

Jim, yes, that is where your vac switch is located.

If a vac switch is replaced and the problem still persists (indicating the existing switch was actually good), all is not lost. You know have a functional spare to add to your onboard tool bag of parts! But this is why testing the pressure (vacuum) of the system with a vacuum tester is a good idea... hint, hint... another good tool to have!

 

[journeyman]

Dennis, thanks for the info. A good part of this post revolved around this vacuum switch and I knew I had this picture somewhere. I posted it to get confirmation of what you were talking about as learning things such as this is beneficial to us all either now or in the future. Good on you!

My periodic issue with the head seems to be the valve at the bowl and will try cleaning it better as suggested. The heads on this and all previous boats have all been on "strict liquid diets", if you know what I mean............ :lol:

 

[georgemjr]

The pressure switch is adjutable. If it is turning your motor off and then back on again, it is doing its job. If you don’t have enough suction, you can adjust it. One other item to check is the vent hose. If that is clogged (which mine was from the tank being overfilled), then the system does not work right. Everytime i pump out, i do so until i hear air being sucked into the vent line assuring it is clear. When mine got clogged I had to remove it to clean.

 

[HMBJack]

Thanks for this George. Very helpful...

Question -
Where do you listen for the vent line sucking air to ensure it's clear?
Inside the head by the bowl? Outside of the boat near the pump out?

 

[DennisG01]

Good point, George, about the vent. If air can't get out, other stuff can't get in so good, either. Jack, the vent is often located below the pump-out deck fitting. Look for a small thru-hull fitting. You should be able to feel and hear (and smell!) the air coming out during a flush and feel/hear vacuum at the fitting during the end of a pump-out. Similar to air escaping through a gas tank vent fitting when filling up.

One word of caution about increasing the pressure via the vac switch spring/thumbwheel... As I mentioned above, I've never actually done this, but I think anyone doing this should be cautious and don't do it without checking for other issues or without a vac gauge. From using/playing with Vac systems for the last 20 years, I've never actually had to do this as the issue was always somewhere else, such as a blockage/partial blockage. Think about it, if the hose is partially blocked, you'll still build full pressure but you won't get the "flow" you want. I mentioned it as a possible cause above just so people are aware of it - but the more likely scenario is a blockage somewhere (either in the big hose, the vent hose or the vent fitting). I second what George said - check the actual vent fitting - just look at it - sometimes it gets clogged with wax buildup or even insect nests.

 

[journeyman]

On the Marlin (and I'm sure other models) the head vent is the small angular clamshell type fitting hullside. Port on the Marlin.

In my mind though, I can't see it being a "vent" in the true sense of the word. I know they call it a vent but there must be some kind of device that opens/closes when needed or else how could the tank maintain vacuum without running constantly? Something to prevent over pressurizing or, in a vacuum tank, a vacuum breaker to prevent collapse?

 

[DennisG01]

Jim, that's the purpose of the duck bills and why there are two tanks. There's the vac tank, and the main "holding" tank. It's the holding tank that is vented and is never (should never) be under any real vacuum or pressure.. The duck bills are the "one-way valve"... that's also why there are 4 duck bills, as opposed to a transfer pump (like a macerator) that only uses 2 duck bills. The duck bills allow the vac tank and the hose to the toilet to be under vacuum. The "stuff" is sucked to the vac tank, but pushed to the holding tank. The vent is very much just an open "vent" to the atmosphere... barring the thru-hull being plugged, the fart filter being plugged up, or the vent hose having a low spot allowing moisture/fluid to collect.

 

[journeyman]

Makes sense Dennis. Always learning...

 

[HMBJack]

We all have vacuflush systems here. This is a good thread I think for all following it.

I personally would like to learn and understand more about the anatomy of the total system and where the common failure points are. If you know of any online resources or books for that matter, please do share.

In the meantime, for my own system, I plan to do the following:
1. check the pressure switch tension on my vacuum generator
2. open the vacuum generator inlet and outlet pipes, look for blockage and replace duck bill valves.
3. check that my vent is not clogged.

My symptoms are: The head works but it seems to back up a bit (doesn't flush water on the 3rd flush or so) and my "pressure" seems to be weak hence my desire to inspect the pressure switch on the vac. generator. My Holding tank pumps out with no problem so I think the duckbills are good there. Thanks for any other ideas for me to do here...

 

[DennisG01]

Journey, you are welcome! It's fun to learn!

Jack, it sounds like you have a clog somewhere. Hopefully it's just the vent/vent line, but check things out where you disassemble, including the bellows in the pump. You can use whatever means you want to for this, but if you remove the vent line from the tank, it should be easy to blow through it. If all is looking good, you may need to snake from the toilet to the vac tank and (for those that have a separate vac tank) from vac tank to holding tank. Although "usually" a clog is going to be between the toilet and vac tank. Just use a snake without any sharp edges or bend them inwards so they don't grab the interior walls of a rubber hose. Sometimes it's easier to snake part way through the toilet, then snake again starting at the vac tank and snake towards the toilet. Flush the toilet with a lot of water before you do it - it may help to soften any clog.

Don't forget the fart filter (if your system has one). If it's gotten wet, it's time for a new one as it can become clogged. FYI, they can be rebuilt (new ones cost $100+) with activated charcoal (fish store), some filter material (just about anything can work) and a PVC male/female connector.

The duckbills in the vac pump have zero effect on a pump out. The duckbills could be completely missing and a pump out would still work just fine. Unless you are referring to an "overboard" pump out when 3+ miles offshore? But that would use a different pump - either a macerator or a transfer pump. If a transfer pump, then yes, duckbills (a transfer pump uses a total of 2) would be a factor.

Here you go guys - I found this online and looked through it - it's a good "study guide"! FYI, the vac tester that it talks about is the tool I was referring to above. It can help narrow down/ID where the problem is in the system.

http://marinesan.com/v/Vacuflush%20-Sup ... ooting.pdf