Correct water temperature sender for 200TDI?

I've recently bought a 200 TDI Disco but notice that the temparetaure gauge doesn't move. I've tested it by earthing the sender end and the gauge worked so I replaced the sender and it still doesn't work!

I can only think that perhaps it has the wrong sender so how can I determine which is the correct one?

It has a viscous fan and I know that keeps the temperature lower than ideal but the needle on the gauge doesn't even move up to the lower end of the gauge markings when the water is noticeably warm/hot!

Thanks.

Richard

first thought is the thermostat is stuck open so water isnt geting hot.... if yo can comfortably hold the top hose it aint hot.

another possibility is an airlock so theres no water at the sender

Thanks, Ricc!

I removed the thermostat when cold and it was tightly closed. Stuck it in a dish and added boiling water and it opened nicely so I'm fairly sure it's not that, unfortunately.

The top hose gets hot - in this cold it's difficult to tell exactly how hot but uncomfortable to hold! And that's with the radiator grille jammed solid with packed snow!

If I remove the sender when the engine is cold water runs out so I'm fairly sure it's not an airlock.

The sender has a green plastic spacer/insulator (as did the one I removed) and I understand that different colour ones are used on different engines. Can anyone confirm that the green one is correct for the 200 TDi, please?

Thanks.

Richard