Water tnk sensor

[cmariner32]

My 89 Carver Santego has a VDO water tank guage that won't read past 1/4 full. I pulled the tank sensor-is a float with a resistor type head. It will read 5 ohms to about 80 ohms going thru the full range on the float. VDO apparently no longer supports this system. Will a fuel tank sensor work-is the resistance the same? It has the standard 5 bolt tank sensor mounting. I tried to pull the top off the rheostat sensor to check and clean the rheostat but it seems permanantly mounted. Any advice appreciated.

 

[Billylll]

It should not be permanently mounted it might be tough to break loose but you should be able to remove it by turning it counter clockwise. Try tapping on it with a screwdriver and a rubber mallet. The gasket might be hard or have calcium buildup on it. On another point try filling the tank and adding a few gallons of Vinager this should disolve the Calcium and might unstick the rods on the sensor.
Bill

 

[Sandy]

Did it work properly at some point in your use? Just asking to see if the sender and gauge are ohms-range matched. VDO range is 10 ohms empty to 180 ohms full for single-station (1 std VDO gauge ) and 0-90 ohms for 1 dual-station sender to 2 std VDO gauges , though they also had US standard gauges and senders for at least single-station at 240 ohm empty to 33 ohms full.
If you have 2 std VDO gauges it sounds like the sender may be OK. Make sure power + and - ground are good. Maybe try good jumpers from gauge to sender and from sender neg to battery ground for a reality check. . Even though the gauge is VDO you might try giving it the "Faria rap."

http://www.autoelectricservice.net/images/VDO_Marine_Catalog.pdf

Their newer water senders are the no-moving-part -type.

http://marine.vdo-gauges.com/fluid-level-senders-accessories/freshwater-level-sender/freshwater.html

 

[sabrejocky]

Fuel level senders will not work as they will short out.

 

[cmariner32]

Sandy...thanks for the info. It has never worked properly since I purchased the boat. It is a one-station guage. The max it will show is 1/4 full even when tanks are topped off. If I disconnect the wire, the guage will shoot to full. I'm guessing the low ohm reading I get correlates to the low reading I get on the guage when the sendor goes thru full range motion. I tried cleaning the wire contacts but no help. I also tried the "Faria rap" (my version is called Sumbich POS)to no avail. Your link provided some very good info. There is one water sender unit that may work. I will call VDO to see if technical support can help me. Saber....thanks for that info, fuel sender apparently not an option.

 

[Oasis]

Replace everything.

 

[cmariner32]

Oasis.....I came to that decision after finally getting the cap off the rheostat housing and looking at what I have. After shaking my head, I plan on ordering a Snake River AKA Tankedge unit for $160 unless someone on here can convince me otherwise. I have a holding tank that I would like to add to my tank monitor as well as the fresh water tank. From past threads, Snake River seems to be a very reliable and cost effective monitor.