VDO water tank guage permenantly reading full.

[oceanfroggie]

Query. The domestic water tank guage stuck reading full so I'm not sure if the sensor in the problem or the guage. If I power the guage off or short the wires at the tank near the sensor it switches from reading full to empty. Is the tank sensor me mechanical on VDO units or electro metallic? Any suggestions.

 

[jimmy_the_builder]

Query. The domestic water tank guage stuck reading full so I'm not sure if the sensor in the problem or the guage. If I power the guage off or short the wires at the tank near the sensor it switches from reading full to empty. Is the tank sensor me mechanical on VDO units or electro metallic? Any suggestions.

Standard euro spec for the sender is to read 0 ohms empty, 190 ohms full - so if you short wires at the sender and the gauge shows empty, then it sounds like the gauge is working correctly and the sender is u/s. I'd pull the sender and stick a multimeter on it at different positions. It might be as simple as a float is stuck; on the other hand I had a wema sender fail recently that had some internal failure that couldn't be repaired, and had to be replaced.

Cheers
Jimmy

 

[oldgit]

If it is ancient enough it will be a mech sender unit.
On previous boat float slid up and down verticle guide.Bouyant part of float was in two bits glued together,they had spit apart and not sufficiant bouyancy to move up guide when tank full.
On second boat the little wire arm attached to float had corroded away and sunk to bottom of tank.
Got a short length of stainless rod and made new one.

 

[DAKA]

Standard euro spec for the sender is to read 0 ohms empty, 190 ohms full - so if you short wires at the sender and the gauge shows empty, then it sounds like the gauge is working correctly and the sender is u/s. I'd pull the sender and stick a multimeter on it at different positions. It might be as simple as a float is stuck; on the other hand I had a wema sender fail recently that had some internal failure that couldn't be repaired, and had to be replaced.

Cheers
Jimmy

If the float isnt stuck, the tube can be easily taken apart and usually be repaired DIY ( I've done one dockside with a lighter and teaspoon.)

The micro switches (magnetically activated) can come apart from the solder , a soldering iron / hot teaspoon usually resolders without any extra solder .

The micro switches are cheap enough under £1 each and can be replaced if they fail, they dont even have to be the same make, there will also be mini resistor diodes attached to each micro switch which again are really cheap and easy to replace .

 

[oceanfroggie]

Thanks guys. Will check those suggestions out.

 

[DAKA]

if you do need parts the correct name is magnetic reed valve switch (not micro switch)