Discussion
If I drive home, or anywhere else for that matter, reasonably sensibly the engine fan comes on as I turn the engine off and stays on for quite a few minutes, I queried this soon after I bought my A110GT and was told by the dealer and other owners that "They all do that Sir"
BUT if I drive home very enthusiastically and get out of the car to the exhaust pinging as it cools and the smell of warm brakes then the fan doesn't come on, surely this makes no sense?
My only explanation is some idea about thermostats opening if driven hard hence the cooling being better so not needing the fan?
I've had a few mid-engined cars, MR2s and a Boxster, that have never done this and front engined turbos RS Megane and a Seat Cupra that only leave the fan on after getting hot!
BUT if I drive home very enthusiastically and get out of the car to the exhaust pinging as it cools and the smell of warm brakes then the fan doesn't come on, surely this makes no sense?
My only explanation is some idea about thermostats opening if driven hard hence the cooling being better so not needing the fan?
I've had a few mid-engined cars, MR2s and a Boxster, that have never done this and front engined turbos RS Megane and a Seat Cupra that only leave the fan on after getting hot!
Do you have telematics? If yes, compare and contrast between normal and 'spirited' driving. Even a modicum of the latter causes (as you rightly suspect) the 'thermostat' to open and it dumps a lot of water temp very quickly, slowly bringing the oil temp down too.
Normal driving I see ~95-105 deg water, ~95-110 oil. Put foot down and water is ~80 deg within ten seconds or so. Oil follows in a minute or two.
The run on fan is interesting though, as it's 'just' an engine bay evac device (which is quite unusual); I don't think it runs the radiator fans after key off. Dunno what the input signal to the engine bay fans is - logically it needn't be water or oil temps.
Nick
Normal driving I see ~95-105 deg water, ~95-110 oil. Put foot down and water is ~80 deg within ten seconds or so. Oil follows in a minute or two.
The run on fan is interesting though, as it's 'just' an engine bay evac device (which is quite unusual); I don't think it runs the radiator fans after key off. Dunno what the input signal to the engine bay fans is - logically it needn't be water or oil temps.
Nick
Experienced that only once after a spirited driving in Sports mode and a short idle for about a minute for cooling the turbo down. I was surprised the bay vents kept silent after I shut off the engine. All the other times, even when I trashed the car before, the vents kept running.
I doubt the logic is related to the coolant or engine oil temperature, as it is a simple bay ventilation.
Not sure if the EWP is running too, impossible to hear, but I would assume that.
I doubt the logic is related to the coolant or engine oil temperature, as it is a simple bay ventilation.
Not sure if the EWP is running too, impossible to hear, but I would assume that.
Edited by k_m on Wednesday 24th July 12:38
Liam22 said:
Perhaps the post-run fans are linked to engine coolant temperature?
And given how spiky the coolant temperature is, I wonder if you can occasionally avoid the post-run fans by switching off just as the thermostat opens?
This seems most likely I think, that the fans are linked to coolant temperature, hence as Nick said driving hard enough to open the thermostat drops the coolant temperature and the fans don't come on.And given how spiky the coolant temperature is, I wonder if you can occasionally avoid the post-run fans by switching off just as the thermostat opens?
Which doesn't actually make any sense, if Alpine is worried about engine bay temperatures it should be triggering the fans from an engine bay temperature gauge not the coolant temp.
I have, on occasion, given the car a little squirt in the final mile to see what the lowest temps I can key-off at are. It hasn't been a successful experiment (the last few hundred metres of 30/20 sections are enough to bring them back up again) - but at any rate I think it's a fool's errand; better I think to switch off with 95 deg bulk fluid temps than go out of one's way to achieve ~85 deg but potentially with a turbo that's locally still red hot (there's no readout for that).
Temp sensors are relatively cheap so it doesn't seem wildly fanciful that there's one in the engine bay. For all we know the fan run-on could be just to protect the rear engine cover and glass...
Nick
Temp sensors are relatively cheap so it doesn't seem wildly fanciful that there's one in the engine bay. For all we know the fan run-on could be just to protect the rear engine cover and glass...
Nick
Liam22 said:
Perhaps the post-run fans are linked to engine coolant temperature?
I can't see this being the case. I do occasionally use mine to pick my wife up from work, just over a mile away, so fluid temps all low and the blue temp light still on, yet the engine bay fans will come on when I sit in the car park waiting for her with the engine off. Hoofty said:
Temp sensors are relatively cheap so it doesn't seem wildly fanciful that there's one in the engine bay. For all we know the fan run-on could be just to protect the rear engine cover and glass...
Nick
Good point with the engine cover and rear window, entirely possible. Nick
To make it even more confusing, MP-Rezeau offers a engine bay sensor kit:
"This switch allows the engine compartment fans to be controlled according to the actual engine temperature. It is an electrical component that is fixed to a metal part of the engine and allows the system to be triggered only when the temperature of the engine bay drops below 45 degrees."
Must be a typo with BELOW 45°C, that wouldn't make any sense!?!
However... as the kit has an extra temperature sensor, it looks like there is none existing in the engine bay, otherwise they could just spoof the signal with a resisitor.
https://www.mp-rezeau.fr/produit/interrupteur-ther...
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