Pumpout issue

[Ken Cross]

This one is new to me. Last year I replumbed the waste system. I filled the tank with salt water to calibrate the new level gauge and it worked great. I then pumped it out and put her away for winter (no problem at all) Yesterday I tried to pump out the tank and couldn't get any flow. The tank didn't try to collapse like the vent was clogged. I sprayed a garden hose into the vent and we could hear water running into the tank. So I don't think it's a vent problem. We were able to pump out by cycling the Y valve and each time we got a small amount of flow. Before I tear the system apart to inspect it does anyone have any obvious answers?

Ken

 

[JamesG161]

We were able to pump out by cycling the Y valve

How did you confirm you had flow?

 

[Ken Cross]

We confirmed flow because the pumpout hose has a clear window in it. each time we cycled the Y valve I saw a second or two of fluid go by in the window.

Ken

 

[JamesG161]

Pump out is a macerator or a deck type RV Lift?

 

[Ken Cross]

The pump out is on the dock. We connect a hose to the deck and open the valve on the hose. I do have a macerator but I leave the through hull closed and the handle for it removed. The Y valve just switches between the deck fitting and the macerator.
Ken

 

[JamesG161]

Since the tank has nothing but water in it, try pumping to the ocean and use your new level gauge to monitor it.

The lifting type of pump out, can break the pump out with a slight air leak in the hose.

 

[NYSail]

do you think you connected the pump out and macerator lines correctly to the y valve?? Not sure I know what you mean by "cycling" the y valve.....

Greg

 

[JamesG161]

When we do a legal pump out to the ocean, we will stop the macerator and allow "back flow" into our tank.
Then after a few minutes of ocean back flow, rinse and repeat.

 

[Ken Cross]

do you think you connected the pump out and macerator lines correctly to the y valve?? Not sure I know what you mean by "cycling" the y valve.....

Greg

While we had the pump out connected and running I had the Admiral move the Y valve to the macerator position and back to the deck pump out position. The small flow we got was each time the valve went to the deck pump out position. I'm thinking there may be something wrong with the ball valve in the Y valve since it's new. Everything worked normally last fall when I tested it with seawater.

Ken

 

[JamesG161]

I'm thinking there may be something wrong with the ball valve in the Y valve.

The would be rare.
What type new level gauge in on your tank?

 

[Peggie Hall HeadMistress]

Your "symptoms" point so strongly at a blocked vent that I'm not willing to rule it out yet.
Just a second or two of flow is a strong indication of a blocked tank vent, 'cuz without a source of air to replace contents as they're pulled out, a pumpout or macerator pump can only pull out a small amoun before it pulls a vacuum that won't let it pull out any more, which sounds like what's happening...and unless the tank is a bladder, you wouldn't see any immediate indication of it starting to collapse...the pumpout would have to pull for a minute or two. Just don't let it continue any longer than that! Did it only happen when the y-valve was open to the pumpout, or also when you tried running the macerator pump? If both, it can only be a blocked vent.

Spring is when mud daubers build their mud nests in anything they can, and they're especially fond of waste tank vents, especially thru-hulls. You said you "sprayed " a garden hose into the vent and could hear water flow, but how strong? Did Is the vent thru-hull a "vent" thru-hull, or an open bulkhead thru-hull that let's you put a hose nozzle against it and back flush the vent line? If it's a "vent" thru-hull, you'd have to clean it out using a screwdriver blade or ice pick.
--Peggie

 

[Ken Cross]

Your "symptoms" point so strongly at a blocked vent that I'm not willing to rule it out yet.
Just a second or two of flow is a strong indication of a blocked tank vent, 'cuz without a source of air to replace contents as they're pulled out, a pumpout or macerator pump can only pull out a small amoun before it pulls a vacuum that won't let it pull out any more, which sounds like what's happening...and unless the tank is a bladder, you wouldn't see any immediate indication of it starting to collapse...the pumpout would have to pull for a minute or two. Just don't let it continue any longer than that! Did it only happen when the y-valve was open to the pumpout, or also when you tried running the macerator pump? If both, it can only be a blocked vent.

Spring is when mud daubers build their mud nests in anything they can, and they're especially fond of waste tank vents, especially thru-hulls. You said you "sprayed " a garden hose into the vent and could hear water flow, but how strong? Did Is the vent thru-hull a "vent" thru-hull, or an open bulkhead thru-hull that let's you put a hose nozzle against it and back flush the vent line? If it's a "vent" thru-hull, you'd have to clean it out using a screwdriver blade or ice pick.
--Peggie

We got flow only when the Y valve was selected to the deck position. I agree it behaved like a plugged vent.

I didn't try the macerator as we are in Puget Sound.

The reasons I didn't think it's the vent are it's a plastic tank and my wife said the top of the tank (which is flat) didn't move down when I applied the vacuum. Also, we could hear water running into the tank when I put a garden hose on the vent. However, I did try stopping up the vent momentarily with my finger when I had the vacuum running and then couldn't detect airflow when I removed my finger. I'm not sure how else to check the vent unless I can disconnect it and run a wire through it. At the tank end, it's a metal 90-degree fitting and I know a wire won't go through there.
Ken

 

[JamesG161]

I thought you said the hold tank had nothing but salt or fresh water in it.
So what is the problem with pumping "no waste" to the Puget Sound for a test at least?

 

[Peggie Hall HeadMistress]

I'm not sure how else to check the vent unless I can disconnect it and run a wire through it. At the tank end, it's a metal 90-degree fitting and I know a wire won't go through there.

Try running a snake through it...or better yet, replace the metal 90 with a pvc or marelon sweep. A metal fitting in a plastic tank is a bad idea for a couple of reasons: metal and plastic have very different thermal cooefficients (translation: they expand and contract at different rates and in different amount due to temperature changes),which cause 'em to leak or put too much pressure on the female tank fitting...and metal corrodes very quickly when exposed to urine, which can happen even in a tank vent.

Is your vent thru-hull a "vent" thru-hull (cap with slit or screen or even just little pinholes in it) or an open bulkhead thru-hull?
--Peggie

 

[Stu Jackson]

Ken, consider taking the vent off the top of the tank and using your dinghy foot pump to blow through the vent hose.

 

[Mark Maulden]

Agree with James...

 

[Ken Cross]

Try running a snake through it...or better yet, replace the metal 90 with a pvc or marelon sweep. A metal fitting in a plastic tank is a bad idea for a couple of reasons: metal and plastic have very different thermal cooefficients (translation: they expand and contract at different rates and in different amount due to temperature changes),which cause 'em to leak or put too much pressure on the female tank fitting...and metal corrodes very quickly when exposed to urine, which can happen even in a tank vent.

Is your vent thru-hull a "vent" thru-hull (cap with slit or screen or even just little pinholes in it) or an open bulkhead thru-hull?
--Peggie

My vent is an aft facing metal hood with a slot for an opening.
It will be a few days before I can get back down there, but I really appreciate the help from everyone.

Ken

 

[Ken Cross]

I thought you said the hold tank had nothing but salt or fresh water in it.
So what is the problem with pumping "no waste" to the Puget Sound for a test at least?

The salt was only to test it when I put it all together. It's no longer pure seawater. I needed salt water to calibrate the new level gauge. At that time I did check the new macerator as well.

Ken

 

[Peggie Hall HeadMistress]

My vent is an aft facing metal hood with a slot for an opening.

I strongly recommend that you replace it with an open bulkhead--aka "mushroom" thru-hull. And also remove what, from your description, sounds like a clamshell cover. It's not only restricting air flow in and out of the vent, but would make it impossible to stick a hose nozzle against the thru-hull to back flush the vent line.
If you'd like input from me while you're on the boat messing with all this, send me a PM and I'll give you my cell #.
--Peggie

 

[NotCook]

Just one question. You mentioned in your original post that you replumbed. Is there another route to the tank besides through the macerator pump? That is, is your Y valve before or after the macerator? If after, switching between the pumpout deck fitting and the overboard port, it would be trying to suck the water through the macerator, which it will not do. Just a thought.