Water level gauge testing. MSC products freshwater gauge.

[Cruiser_Boy]

I have an in line MSC products water level gauge. It looks like this:- http://mcsboatproducts.co.uk/

I have the analogue meter. I thought at first my tank outlet was blocked but it looks like the gauge is showing

half full when the tank is empty. So either the sensor is faulty of the gauge.

Does anyone know of a simple way of testing these items or have any experience of common problems ? It has

worked well up until a few days ago.

[Sea Dog]

10 minutes ago, Cruiser_Boy said:

I have an in line MSC products water level gauge. It looks like this:- http://mcsboatproducts.co.uk/

I have the analogue meter. I thought at first my tank outlet was blocked but it looks like the gauge is showing

half full when the tank is empty. So either the sensor is faulty of the gauge.

Does anyone know of a simple way of testing these items or have any experience of common problems ? It has

worked well up until a few days ago.

Theres a small screw in the sensor (in the supply pipe from the fw tank) to calibrate the levels. This doesn't explain why it would suddenly go wrong if it's been right unless you've disturbed something, but if you've ruled that out and have ensured the connections are ok it might be worth a tweak before you go to any expense. I'm pretty sure the installation instructions are on the MSC website.

Edited October 27, 2019 by Sea Dog
Change few back to fw after autocorrect had had its oar in!

[ditchcrawler]

1 hour ago, Sea Dog said:

Theres a small screw in the sensor (in the supply pipe from the fw tank) to calibrate the levels. This doesn't explain why it would suddenly go wrong if it's been right unless you've disturbed something, but if you've ruled that out and have ensured the connections are ok it might be worth a tweak before you go to any expense. I'm pretty sure the installation instructions are on the MSC website.

I have them here if not, but dont have a scanner only a camera 

[dor]

If the vent pipe has a dip in it, then if this gets water in it it can upset the reading, which relies on measuring a very small pressure difference.

On mine there are small pots on the sensor circuit boards to calibrate it.

 

[ditchcrawler]

51 minutes ago, dor said:

If the vent pipe has a dip in it, then if this gets water in it it can upset the reading, which relies on measuring a very small pressure difference.

On mine there are small pots on the sensor circuit boards to calibrate it.

 

Mine doesn't have a vent pipe, it just T's into the pipe between the tank and pump with a Hep 2 fitting

[WotEver]

39 minutes ago, ditchcrawler said:

Mine doesn't have a vent pipe, it just T's into the pipe between the tank and pump with a Hep 2 fitting

Methinks he meant the water tank vent pipe

[PeterF]

I checked mine by removing it from the pipework (I have a valve to isolate the sensor) and then connected some clear plastic hose I had lying around to the sensor, then I could add water with a kitchen jug and test it and recalibrate it by filling the hose to the same height as the water tank. I had to wind some insulating tape around the hose to get the outside diameter to match the pipe. Washed it out with clean water afterwards and refitted.

[ditchcrawler]

42 minutes ago, WotEver said:

Methinks he meant the water tank vent pipe

I didn't think of that

[dor]

10 hours ago, WotEver said:

Methinks he meant the water tank vent pipe

Correct!

[Dr Bob]

WHen we bought our boat, it had one of these sensors on the water tank to pump pipe, but no gauge. We presumed the gauge had gone faulty so the previous owner scrapped it. I bought a cheap voltmeter ( to 3 decimal places) and attached it to the sender. The voltage varied with level but drifted badly.

At the same time we were having big problems filling the water tank and identified the problem was a dip in the vent pipe as posted above. Removing the vent pipe solved both issues. The voltage display is now rock solid and on empty is 3.620V and full is 5.90V. 

We got a new fitting welded on so the vent pipe does not have a dip in it. 

Likely the original gauge was fine.

[Cruiser_Boy]

HI All,

Thanks for the replies.

I opened it up today and tweaked the 'empty' pot until the gauge read 0%. Filled the tank and a full tank read as 100% so probably the pot moved with vibration.

It is close to the pump so must get some vibration every time the pump turns on. It's quite a coarse pot so if it goes again I will change it for a multi turn.

On my last trip I was topping up at every opportunity and it was taking a very long time to fill from 50% - 60% so maybe it has been faulty for a few months and

I only noticed recently when the tank was empty.