Quote:
Originally Posted by HighlandPete
I suggest the N57 engine warms a lot faster than the older M57. No way would my 330d heat that fast at 2°C.
I've just looked at some trips in the 330d, at 1 - 3°C, (new thermostats). After 10 miles the ECT was still climbing, but only 82°C, dropping back to 78°C on the easy descent over 1/2 mile.
Another trip, after 13 miles at 6°C, the ECT was still climbing, but only 87°C.
There are several factors which come into play. Battery condition and whether the electric PTC auxiliary heater is running full capacity, assisting cabin warm up. The mpg during the warmup phase, engine loads over the mileage.
It's one thing I notice with the 535i, all spare heat is used to heat the cabin, no electric auxiliary heating element to help the HVAC system. That definitely slows the warmup phase.
Consider the engine load factor, in the 330d. The above example was reading 36.2 mpg at the 10 miles mark. That's a light fuel consumption, from a 2°C cold start.
Another example in the 330d was 'up the glen' at -4°C, climbing about 200 metres in 8.3 miles. ECT was just tipping from 87 - 88°C when I turned around. OBC was recording 21.5 mpg.
Return trip to home, immediately dropped back to 85/86°C. After the 8.3 miles to home was just 83°C. OBC showing 29.1mpg. Load and mpg reflecting not enough work to heat the engine, simply cooling down over distance.
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Speaking of Battery the car is just over 5 years old and on its original battery, although I’ve had no low battery warnings at all yet. The auxiliary heater was definitely in play today, there was warm air coming through to the cabin in less than 2 miles!
What I find aids engine warm up is accelerating a little on the inclines whenever possible, but of course not revving it too high while the engine is not up to temp yet.
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.