My 110 took to running cold over the winter. I could nearly get to normal temp on long steep slopes but as soon as I got to the top the temperature would drop back down. This caused my power to drop and my fuel consumption to increase by 4mpg. Even as the weather warmed up there was no improvement.
I checked all the usual suspects to no avail. The usual interweb advise was to put on an electric fan (I took the viscous off to check. Not a bit of difference) or "they are all like that. Live with it." Having had her for over 20 years/140k miles I know what she is normally like so I ignored that as well.
A chance conversation with our workshop manager revealed that there is a thermostat for the oil cooler in the filter housing. £11 and a bit of crawling around underneath and the problem is totally fixed! The heater works under normal driving. Power is back up, and I am back to 30mpg.
This appears to be the same part in the TD, 200 and 300TDi. Possibly there is something similar in earlier and later engines as well. Knowing Landrover from the 80s and 90s it is entirely possible that the oil thermostat was not even fitted in some of them.
There you go, cheap fix and you do not have to put up with no heat!
