Holding Tank Indicator Failure

[Kobi Maru]

The indicating needle for my holding tank gauge now stays on 1/2 full. I have pumped my tank several times, so I am confident it is not working properly. I suspect the sending unit has failed. Does anyone know how to confirm/test this??? Also, where can I purchase a replacement?

 

[Peggie Hall/Head Mistress]

What brand is the gauge?

 

[Dick McKee]

Kobi..if it is a Wema like we have on our 430..

most likely it is just stuck and needs to be cleaned. If it is a Wema you need to be careful when you remove it from the tank. On the inside of the tank is a ring that matches the ring of screws on the sending unit. You must start by removing ONLY ONE screw and replacing it with a screw about 4" long with the head cut off. This will allow you to then remove the other screws and hold on the 4" screw while you remove the sending unit. You must carefully reach between the sending unit and the tank and hold on to the 4" screw. After you have lifted off the sending unit you then can reach in the tank, hold on to the ring, remove the 4" screw and finally the ring.You can then unscrew the black plastic tube off the sending unit and clean and free up the slide located inside. Hope this helps Dick McKee

 

[Robert Polk]

How to clean

I have had the same problem on our 460. The unit just scews into tapped holes in the tank so I don't need to follow the procedure in the other response. I drop the unit into a pail of stong solution of warm water and Dawn and shake it around until I can feel the float inside the tube moving frrely. Scub the sides with a coarse toothbrush to clar the small holes. I even use a tooth pick to clear the holes. After the holes are clear I again put the unit in saoy water and shake vigorously to get all of the stuff inside the unit out and can get the float very loose so it easily travels the length of the tube when I invert the sensor.

 

[Mark Johnson]

Here's what I used to do...

on our 460. I used to put about 5 gallons of fresh water in each holding tank along with about a half bottle of dawn, joy or some other dish washing soap. The motion of the boat thru various sea states and boat wakes sloshed the soapy water within the tanks and kept the sending units clear. At the end of the weekend we would empty the tanks. We would go thru this procedure every few weeks. In the 3 years I owned the boat, I never had to remove the sending unit in either holding tank. They were Wema gauges too. Those of use who have Wema's know they are prone to clogging.