I have a 4.4 V8 2005 LR3. It ran low on coolant until the heater stopped working. The drove fine for many miles probably 70-100 at 65mph in this state and it never gave a low coolant or overheating error. I have since added coolant but I have noticed a white smoke comes from the exhaust after the engine has run for a few minutes. Is this a head gasket failure or could there be another way for coolant to enter the combustion chamber? It is odd because the car is running fine minus the white smoke. Can the LR3 overheat without a dashboard warning? I thought that only happened with the older engines.