Water Temp Gauge Problem

Hi all,

I've been surfing the foru for a while now but decided to join in the hope that someone can help explain a problem I appear to have. My series 1 Disco 200Tdi's temperature gauge 'appears' to climb 2 or 3mm above norm (straight down) when I turn the heater on. On turning the heater off the gauge slowly settles back down to normal. Any ideas whats causing this? Tips to diagnose and cure? All help appreciated Ta in advance guys

Airlock in radiator perhaps.Theres an inspection cap on the 300 not sure on the 200.
I removed the cap & squeezed the hoses & changed the thermostat aswell...

bleed valve is on radiator on 200. replace with domestic radiator bleed valve - about a quid. and/or fit 300 thermostat housing.

Thanks for that guys but after further investigation it seems that its not just turning the heater on that cases the temp gauge to rise; if I turn on anything drawing a bit of current i.e. heated rear windscreen or headlights it does the same thing

Sounds like a dodgy earth somewhere......