Holding Tank / Tecma toilet issue

[Tym]

On our R-29 we've just started having a strange problem with our holding tank. For some reason, with the holding tank probably about 1/2 full, we couldn't pump it overboard. Since we could hear the pump running, we thought it might be a pump priming issue, so I took a garden hose and filled the tank to the top using the pump out port on the starboard side. After doing that, the tank pumped overboard normally until it was fully empty.

Next trip, with the tank again half full, the tank wouldn't pump overboard again even though we hear the motor running. I expect I could repeat the procedure of filling it to the top and then having it work, but thought I'd ask if anyone else has been having this problem too. And yes, the overboard valve was definitely open when we couldn't pump overboard. The system has worked perfectly for a year, and now suddenly we have this problem.

One more thing, when the tank was filled the green / yellow / red indicator light on the flush panel did NOT turn red -- it stayed yellow. We've never had a full tank before to check the function of the red light, so maybe it's never worked, but...

Since we have a water maker we have the toilet flush plumbed to flush with fresh water, but I don't think that has anything to do with any of this so...

Appreciate any ideas or suggestions,
Thanks.

 

[Levitation]

I suspect that a solid of some sort (tissue?) was plugging the suction side the pump and that filling the tank agitated it enough to dislodge it... GIve ANdrew a buzz on this problem...

 

[Spirit of Gratitude]

Tym,
I suspect that you have a partial obstruction in the mascerator pump itself. When it spins it creates a suction. Your suction is being compromised in some way I feel. When your tank is full you have more gravity weight to help the pump. But if you are starting from half a tank then you do not have as much help of the gravity weight.
It is not what anyone wants to do, but I would pull the mascerator pump and clean it. If you go over to the pump out station and fill your holding tank with fresh water and pump it out three times, maybe adding a bit of bleach on the water fill ups, then it will not be quite as bad when you go to pull the pump. You may even save the last water fill up to be pumped out where you are legal to do so overboard since you say it will work from being at a full tank.
Maybe no bleach on the last water fill up if you are going to pump overboard.

Anyway, just my thoughts,
Stuart

 

[commander bill]

My tank has stains (inside tank) up to about 40% of level. I do not have and level instrumentation so I have to raise the engine hatch and look at the tank to determine level. One of the things I have noted is that the stains make it difficult to actually determine level if less than 40% full. I usually have it pumped out at my slip during the season but at end of season I pull it to the edge of my cow pasture and pump on ground. I usually add dish liquid before drive home and after all the good stuff is on the ground I use the shower sprayer to dump the fresh water tank into the toliet. Then I pump it on ground again before I winterize. I am only able to tell when level is gone by listening to pump which will sound very different when the last of the good stuff is gone. If anyone knows a way to flush out the stains on inside of tank so I can tell level below 40% please let me know

 

[Tym]

Thanks for the replies so far.

As far as removing and cleaning the macerator pump, there's a problem beyond it being a messy job that our boat has that some may not. We took off the wall at the foot of the 2nd stateroom to get access to the pump area to see what we were up against, and found that the pump is located behind (farther forward in the boat) the air conditioning / heat exchanger unit. To remove and clean the macerator pump probably means removing the A/C unit for access. So a big messy job becomes a huge messy job. And since the A/C unit is working just fine, I hate to mess with it. (If it ain't broke, don't fix it.)

Also, the macerator pump is physically located about a foot above the holding tank - so it must produce some pretty good suction. Seems strange that mine could be blocked when it works fine with a full holding tank. I'd hate to go to the trouble to clean it and find it didn't need it and all I have is a priming issue somehow.


This is why I'm curious if anyone else has had this problem. We did try and prime the pump while underway by doing hard turns left and right and changing the pitch of the boat with the trim tabs - all to no avail.

And one last thing, if anyone with a Tecma toilet has ever seen the red light come on to indicate that the holding tank is pretty full, I'd appreciate hearing just that. Thanks again...

 

[Tampa Tug]

Had an issue with the red light not coming on, even when we filled the tank all the way up with water to do some checks. Seems as if the sensors, which are just stuck to the outside of the holding tank, were the culprits for a recent problem..was blinking yellow and green when it should've been red. Til we get new sensors installed, I'm keeping an eye on the level just to be safe.

 

[Spirit of Gratitude]

Hey Tym,
For what it is worth, mine in mounted above the holding tank by at least a foot also. Other than that I don't know what to tell you. Maybe you can fix it without getting to the pump. Hope that works out, for it sounds like a bugger to get to.



Stu

 

[Levitation]

For the stained tank walls - the first thing that comes to mind is chlorine bleach...
Fill with water and a quarter cup of laundry detergent, agitate, then pump dry... Follow with a clear water rinse 3 times to remove solids and foam...
Then fill with water until just above the stain level
Then add a quart of liquid bleach and let it set for a few days...

An alternative to bleach would be Simple Green or even Pine Sol - but I prefer bleach for it's corrosive action on the organics staining the plastic...

 

[CaptMac]

Same problem (stained black water tank walls - can't see liquid level) on Island Ranger. Andrew contacted the tank manufacturer for me, and they recommended using dishwasher soap. It is pretty aggressive - I put in a lot and 1/2 filled the tank with fresh water. Took the boat out for a spin and then to the pump out station. I repeated it a couple of times...It helped -

Mac

 

[Rhapsody]

Hi Tym,
We have seen the red light go on and it was time to pump out. Hope this helps.

 

[Tym]

Yes, that's very helpful and exactly what I was asking. Now I know the red light should work and does work on an R-29. Thanks very much.

 

[LADYBUG TOO]

Great discussion. The macerator pump has a minimum "net positive suction head" (NPSH) limit meaning that it can have difficulty priming at lower holding tank levels. Once the NPSH requirement is satisfied by filling the tank to a higher level, the pump can prime and will likely retain its prime until the tank is empty. My guess is that your pump is functioning normally. I don't think these pumps can handle very much suction lift. I sure would not want to tackle cleaning the pump unless it just becomes intolerable.

 

[Wolf Pack]

The red light also works on Wolf Pack's Tecma to indicate "full". 😎

 

[Spirit of Gratitude]

The Macerator pump on Spirit of Gratitude will pick up the waste no matter what level the holding tank is at.
I guess I just assumed that was normal. It sounds like from what I am reading here, that it is not.
I had the same mounting setup on my old boat and it would also pull from the tank at any level even being mounted around 18" above the holding tank.
I guess I got lucky twice. Go figure!

It's no fun pulling those pumps apart, but if you have your boat long enough you will have to do it at some point. Or hire someone too. 🙁