Water gauge sensor sealing

[Nigel Crompton]

(sigh)

I now find that the multi-prong water level sensor is not sealed to the top of the tank and leaks when the tank is full. Bizarrely the inspection hatch, gauge sensor and pumped outlet to taps are not at the highest point of the tank.

It's not a leak I can ignore as Herself always insists on filling the tank at every opportunity.

I can only access directly from above, I can't see the side. Are these things masticed in place. Don't wanna just pull it .....
It's a Hymer if that matters.

 

[gus-lopez]

Very odd not being sealed ?

 

[pappajohn]

I would expect it to be a complete unit with a sealing ring inside the tank and a second seal under the securing nut outside.
Maybe not tightened at manufacture or worked loose with vibration.

 

[tonyidle]

It is sealed with a 'rubber' ring. The tank and cap aren't necessarily very smooth at the sealing face so the rubber has work to do. Occasionally when rotating the cap to tighten it the seal deforms. Silicone grease on the sealing faces and threads helps. As does a certain amount of "feel" when tightening. As an alternative to silicone grease this is one of the very few places where silicone sealant is useful on a motorhome - it lubricates, sets to stay in place, and is easily broken if the cap needs to be removed. Use the type available for aquarium construction - it doesn't hurt fish or humans and is stronger than bath sealant. The cap is screwed onto the tank by the way.

 

[Lenny HB]

I can only access directly from above, I can't see the side. Are these things masticed in place. Don't wanna just pull it .....
It's a Hymer if that matters.

There is a big plastic nut inside the tank, if you are lucky it will be finger tight if not a pain in the ar*e getting at it with water pump pliers through either the inspection hatch or the water pump fitting. It has a plasic washer to seal it either black or white.

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[Nigel Crompton]

The bugger of it is, I assumed the leak was because I hadnt tightened the inspection hatch sufficiently, so I gave it a spray of silicone screwed it on and now cant get it off ....
Given up for now, report back tomorrow ...

 

[mitzimad]

It is sealed with a 'rubber' ring. The tank and cap aren't necessarily very smooth at the sealing face so the rubber has work to do. Occasionally when rotating the cap to tighten it the seal deforms. Silicone grease on the sealing faces and threads helps. As does a certain amount of "feel" when tightening. As an alternative to silicone grease this is one of the very few places where silicone sealant is useful on a motorhome - it lubricates, sets to stay in place, and is easily broken if the cap needs to be removed. Use the type available for aquarium construction - it doesn't hurt fish or humans and is stronger than bath sealant. The cap is screwed onto the tank by the way.

as a plumber i wouldnt put silicon on any washers, ive found it just lubricates the surface and causes the washers to twist out of place

 

[tonyidle]

as a plumber i wouldnt put silicon on any washers, ive found it just lubricates the surface and causes the washers to twist out of place

That's where the 'feel' bit comes in. I agree in general about plumbing fittings because it isn't necessary anyway - the rubber washer is enough - but tank plastics on motorhomes are a whole new can of worms. Some leak no matter what you do (usually the very large ones) and whilst over-tightening isn't the answer sometimes the thread form and fitting diameter means very little pressure is placed on the sealing washer. Silicon does exactly what you suggest which means the tightening point is critical. Stop before it extrudes the washer .

 

[Nigel Crompton]

Got the sender out now. Low and behold there are no washers/seals fitted to either side of sender.
Cheers Hymer!
Can't seal with silicone mastic on top because I can't turn the nut in the tank, I have to hold the nut and turn the sensor
Now scrounging around for summat to make washers from ....

 

[Nigel Crompton]

Fixed. Used pieces of 3mm closed cell foam ( from Hoya photographic filter cases) inside and out.
Externally checked the sender on the waste tank too; that's not loose as the other one was but can't see a washer under that either .... but that never gets 'brimmed' !

Thanks for the help and advice.

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[SuperMike]

Our water level sensors (3) are stuck on the outside of the tank, but then hey, it’s a Winnebago. Only the Very old-mo type fella would understand.

 

[Jev88]

CAK Tanks - have been very helpful in the past - sent them measurement and photo and they supplied correct rubber gasket or sealing ring for other tank problem I had.