Disco 1 warning light

[Sprite001]

Hi there
Just got the Disco (1994 3.9 series 1) back together and running and after a while a red light comes on the dashboard.
The light looks as if it is a thermometer with a gear shape around it.
Could it be the gearbox warning light??
If so how do i fix it??
The engine has been running for around 20 minutes in park, when the light appears, and when the engine is stopped and allowed to cool it goes off.
Any help would be appreciated.
Cheers Phil

[pistolpete]

I had a thread about this.. its a sensor underneath the radiator...

this is the thread, though my problem is different

http://www.aulro.com/afvb/discovery-1/131724-warning-light-question.html

its a auto fluid temp warning light.. not sure what the problem is though

[DiscoMick]

Problem with the oil cooler? Just guessing...