I'm trying to diagnose what I believe is a thermostat that is stuck open.
My newly acquired 300TDi Defender runs very cool. It has a recent radiator replacement and a new water pump. The thermostat was replaced at the same time, and I fear the thermostat is bad and stuck open.
After 30-40 minutes of driving, it will just reach the "C" on the temperature gauge. My newly installed MadMan EMS (incredible product) tells me that the maximum coolant temperature is 55 degrees while driving around town and on the motorway. Needless to say, the heat is about useless.
I've tested the viscous fan, and it appears to be free. I can stop it while at idle with a rolled up newspaper.
Do 300tdi's simply run very cool, or does this sound like a bad thermostat?
Vin