Quote:
Originally Posted by Hooded
You do see coolant temp drop back when off load if the engine hasn’t had chance to get completely heat soaked fully and up to optimum temp Yet. While mine was still warming up it dropped back from 80c to 76c going downhill, but once the engine was at the optimum oil temp of 100c you didn’t get any coolant drop back below the initial thermostat opening temp of 88c again. Your example above in -4c going downhill on the way back home and dropping back to 83c from around 87c was down to the engine never quite getting heat soaked enough to it’s optimum running temperature before starting back down hill in the cold.
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Yes, I'll see the drop back during the warmup phase, if the load reduces. An observation in the 535i, it typically cross references the instant mpg reading 50+ mpg, over a reasonable distance. Fits with no waste heat to spare.
There are no issues once the ambient temperature is above ~7°. Then it is progressive heating and holds above the thermostat opening temperature.
Radiator shutters are definitely the answer.
