Vacuum flush system

Stachouse

New Member
Jul 27, 2018
1
Boat Info
1988 340 Sundancer
Engines
Twin 7.4L 454
i just bought my 1988 340 Sundancer few weeks ago and been knocking out and running into problem after problem. The toilet when flushed just fills up with water and will not go down. When the head switch is turned on the vacuum pump just steady runs and never stops. I do not see any deck fitting for waste to pump out the holding tank. All I see is the old mascerator pump which has been disconnected. The treat switch on dash I believe has been disconnected and the treat and hold treat and discharge lights do not work which I figured wouldn’t since it’s against the law to discharge overboard. Anyone with any knowledge or help/insight on what I can do to atleast use the bathroom would be greatly appreciated. I already know down the road I’m going to have to add a way to pump the tank out. My biggest concern/problem is I believe the vacuum system not sucking the contents from the toilet to the tank.
 
I am not familiar with your year and model boat, but there has to be a deck fitting to empty the waste tank. Find that and empty the tank. That is likely not your problem though. If your system is a Vacuflush, since you know your vacuum generator motor is running, I would buy a rebuild kit which includes duckbills, o-rings and a diaphragm and install all of those parts. I suspect that will address whatever issue you are having as those are the bulk of wear parts in a Vacuflush system.
 
If your toilet isn’t flushing you’re not producing vacuum. Bellows and duck bill valves would be the things to look into.

There could also be a clog between the toilet and the pump. Actually this should be your first cost free check, but the pump running endlessly indicates low vacuum production.

Poor pump function or a vacuum leak somewhere are strong possibilities.

Hard to believe that there’s no pump out fitting on a gunnel somewhere. My boat had the old treat/hold/discharge system as well, which is long gone, but a pump out option was original equipment as well.

With pump running and some water in the bowl, go at it with a plunger. God knows what might be stuck in a line.

Next take the pump apart and look for clogs or something stuck in a duck bill valve on the incoming side.

Unpleasant job. Get some gloves.
 
"Been there done that"! I had the same issues last year when we purchased our 390 EC. The above notes are both good ideas. The items that need to work in order for this system to function properly are (in order from bowl to tank): bowl seals (half ball valve and seal in head bowl), tank vacuum switch (outlet side of accumulator tank), duck bills (inlet side and outlet side of pump, most have two duck bills at each end), pump bellows (inside the pump housing, two critical o-rings to keep sewage from leaking out of the pump), armature connecting pump to bellows (outside of the pump).

Free checks: if the water level in the toilet goes down in any amount while the pump is running, you have leaking seals.
As noted above, make sure there are no clogs. Next, move to the pump. Check the operation of the armature connecting the motor to the bellows. If that arm is intact and the bellows are moving up and down, move to the duckbills. Duckbills are cheap, not free, and easy to check (but a nasty job). Unscrew the fitting coming into the pump and going out of the pump. You should have two duck bills on each side. If they look at all suspicious (deformed, cracked, "open") replace them. Again, this is a nasty job so you only want to open this up once. If you replace the duck bills, stop and check for better performance of the system. If still not building vacuum (pump runs continuously), find a way to check the line fittings for leaking. Start at the bowl, and work your way to the pump. Start by simply checking all band clamps and make sure they are all tight. You can buy a vacuum tester and plug it in at each fitting to check all items up stream. Once you get to a fitting that will not hold vacuum, you know you leak is in the next fitting "up stream". If you dont find a leak, find you accumulator tank. On the downstream end is the pressure switch. You can manually manipulate the switch and that should turn off the pump. At this point I don't see this as your problem though as you state the water does not go down which indicates you have zero vacuum. This would more likely be a problem if you make vacuum and the pump does not shut off.

All of the parts for this system are crazy expensive (except for duck bills) and caution should be used just buying parts to throw at it. Pump complete, $870, bellows $80 - $120, rebuild kit $200, vacuum switch $120, new o-ring kit $25 - $60.

Check the items above and if you are still stumped, feel free to PM me. I have been through every nasty inch of my system over the last year. it has paid off as the vacu-flush work awesome when done, but it can be frustrating - and gross.
 
I found a guy named Brad in Sandusky, Ohio...Marine Discounters who is the undisputed Vacuflush king.

I got a new pump in kit form for half the cost of a built one.

Generally speaking his prices are low and his know how is amazing.
 
If I can hijack this thread for a second I also have a different vacuflush question. According to the instructions, you are supposed to be able to lift the foot lever to add water to the bowl. My lever doesn't lift but it automatically fills the bowl after each flush. Is this supposed to work this way or is something wrong. Otherwise it works fine but I was trying to add a little more water when cleaning the other day and noticed that the lever didn't budge (upwards).
 
If I can hijack this thread for a second I also have a different vacuflush question. According to the instructions, you are supposed to be able to lift the foot lever to add water to the bowl. My lever doesn't lift but it automatically fills the bowl after each flush. Is this supposed to work this way or is something wrong. Otherwise it works fine but I was trying to add a little more water when cleaning the other day and noticed that the lever didn't budge (upwards).

That is true, lift the pedal and water should start to fill the bowl. When you say, "Fills" the bowl, do you mean literally fills it to the top? Mine only adds a few inches of water to the bowl which is the desired amount. A full bowl sloshes around while underway, and fills the holding tank much faster.

I would take the foot pedal assembly apart for inspection. Something seems wrong.
 
If the bowl is filling after each flush you’re not holding the pedal down for the suggested three (?) seconds and some of the water designated for the flush is filling the bowl once the ball valve closes.

As far as lifting the pedal to add water, inside the plastic foot pedal is a metal rod with an arc shaped part welded to its top.

That arc rides over a ball shaped plunger on top of the water valve.

If the inside surface of that arc is rusty or rough it won’t work well. You can also make an adjustment there by bending that part.

It should also be lubricated at that friction point.
 
That is probably exactly what I am doing...not waiting the 3 seconds. Since my boat came from a lake and I haven't re-plumbed my gray water and re-commissioned my macerator yet, all of my water usage goes to the holding tank so I thought that "quick flushing" would just be that much less going down the pipe. I'll have to take the pedal apart and take a look to see why it won't go up. Right now it's working fine so I also may just wait until the end of the season rather than opening another can of worms. At least now I know it's not normal.

Thanks again!

If the bowl is filling after each flush you’re not holding the pedal down for the suggested three (?) seconds and some of the water designated for the flush is filling the bowl once the ball valve closes.

As far as lifting the pedal to add water, inside the plastic foot pedal is a metal rod with an arc shaped part welded to its top.

That arc rides over a ball shaped plunger on top of the water valve.

If the inside surface of that arc is rusty or rough it won’t work well. You can also make an adjustment there by bending that part.

It should also be lubricated at that friction point.
 
All of your water should go to the holding tank. I doubt that you find yourself outside of the 3 mile limit for black water discharge at all times. Unless you find yourself navigating in waters outside the 3 mile discharge limit, I recommend removing the handle from the macerator discharge seacock just to be sure. When the Coasties board you, you can affirmatively state that your overboard discharge is non-operable.

Jaybeaux
 
What you’re doing isn’t really a problem you know. It’s the same amount of water headed to the holding tank either way. It’s just a matter of what portion of that water contributes the the current flush or the next one.

I have heard though that the 3 second rule keeps the pump and valves wet in anticipation of the next flush since the flush is complete and the waste has passed by then.
 
I normally "double flush" to make sure the nasty stuff gets all the way back into the tank and past the duck bill valves. It fills the tank faster, but at our marina pump outs are free.
 
I looked at my neighbors boat yesterday to see where his pump out is. Yours might be the same.

His is on the right side of the boat, looking from the stern. It's about a foot forward of the fuel fill just behind the window opening for the head. Fresh water and fuel are on the left, head and fuel on the right.
 
What you’re doing isn’t really a problem you know. It’s the same amount of water headed to the holding tank either way. It’s just a matter of what portion of that water contributes the the current flush or the next one.

I have heard though that the 3 second rule keeps the pump and valves wet in anticipation of the next flush since the flush is complete and the waste has passed by then.

I tell my guests about the "Rule of Three"... Nothing except what comes out naturally goes in the toilet - no foreign objects!
1) Three sheets max!
2) Three times max!
3) Flush for 3 seconds... "Or you can unclog the pipe"

Haven't had a clog since I added this to my pre cruise briefing. LOL
 
I normally "double flush" to make sure the nasty stuff gets all the way back into the tank and past the duck bill valves. It fills the tank faster, but at our marina pump outs are free.

"Liquid only" aboard the Rowe Boat.............Failure to follow this rule results in banishment.
 
All of your water should go to the holding tank. I doubt that you find yourself outside of the 3 mile limit for black water discharge at all times. Unless you find yourself navigating in waters outside the 3 mile discharge limit, I recommend removing the handle from the macerator discharge seacock just to be sure. When the Coasties board you, you can affirmatively state that your overboard discharge is non-operable.

Jaybeaux

We are often outside 3 miles so we used our macerator all the time on my previous boat. That is winter project "#2", so to speak, this year getting that hooked up again. Project #1 will be re-plumbing the grey water.
 
"Liquid only" aboard the Rowe Boat.............Failure to follow this rule results in banishment.

That would be a good way to prevent guests from returning!
I have a laminated “head rules” card with instructions that I put on the head wall when guests are on board. It includes the standard rules of nothing in the head other than P and Poo. I also tell them to flush the waste first, then use the TP and flush it separately.

Having rules on the wall for them to read is less embarrassing. The instructions include a note that there are plastic lined paper bags in the head storage compartment for discrete disposal of fem hygiene products that cannot go in the head. I cant recall where I bought them but my wife tells me they are appreciated by women that come aboard.
 
I provide a roll of doggie poo bags in the head for disposal of those items. Cheap and convenient.
 
So I had close to the same problem: I have a 84 searay 340 with a Mansfield toilet model:848. I had a power outage and guests over filled my toilet. There is no power to treat & discharge. I used a shop vac to empty the tank (not fun). Suction pump comes on it always has toilet seems to be working fine. But still no power to the panel with the LEDs treat, hold or release? And no power to the full,empty and don’t use L EDs in the bathroom. Any help would be greatly appreciated....
 

Forum statistics

Threads
112,948
Messages
1,422,806
Members
60,930
Latest member
Ebrown69
Back
Top