[applegrew]

Today after I parked my car and turned it off, I could still hear the loud humming noise; presumably of the radiator. Video of the same is below.

https://youtu.be/2H_tTHr_zmo

I tried turning the car on and off couple of times. Then after few times it finally turned off. I called the service centre and they mentioned that this happens sometimes, to cool down the engine if it is too much hot.

Heat wave has been going on in Hyderabad for quite some time now. Also recently we completed a trip to Bangalore and Coorg, it never happened then. This has happened to me for the first time.

Has anyone faced anything similar? More importantly - Is this is a feature or a bug?

[Jeroen]

On many modern cars the electric fan might continue running for 1-2 minutes after the engine has been shut down. To provide cooling obviously. It doesn’t have to be a particularly hot day or you might not have driven your car hard either.

On my Jaguar de fan remains on for about a minute, even at current ambient temperature of around 5oC.

It’s not a bug and I would not call it a feature either. Comes as standard with certain engine design. Whether yours is working correctly is impossible to say. But as long as it shuts down within maximum 1-2 minutes I would say it’s fine.

Now here’s a thought: did you check your owners manual what it says?

Jeroen

[Rodie09]

This is pretty normal. Seen on many cars and perhaps most have such a safeguard to cool the system to a preset temperature. As Jeroen said , there is definitely nothing wrong as long as the fan stops after a minute or two.

[Night Raven]

Originally Posted by applegrew

Has anyone faced anything similar? More importantly - Is this is a feature or a bug?

Don’t worry, I have experienced the same few times in my Compass petrol. It was after driving the car in first gear or under load for sometime and turning off the engine immediately without idling. It shuts off by itself after sometime.
Did you check the engine temperature or coolant temperature in MID while this was happening? Do check the coolant levels also.

[rjkapur]

Originally Posted by Night Raven

Don’t worry, I have experienced the same few times in my Compass petrol. It was after driving the car in first gear or under load for sometime and turning off the engine immediately without idling. It shuts off by itself after sometime.
Did you check the engine temperature or coolant temperature in MID while this was happening? Do check the coolant levels also.

It doesn't always shut down on its own.

[Jeroen]

Originally Posted by rjkapur

It doesn't always shut down on its own.

If it doesn’t shut down by itself, something is amiss. But you have to wait a couple of minutes. That is a long time if you have nothing else Romeo, but stare at the bonnet.

On my Jeep Cherokee the relais that controlled the fan malfunctioned now and then. Which meant the fan kept running indefinitely, well at least till it drained the battery!

If that is the case get your car checked, should not be difficult to check. If anything a quick swap of the relais for an identical one should give you an idea whether there is a problem or not.

Jeroen

[balenoed_]

Originally Posted by rjkapur

It doesn't always shut down on its own.

Just curious, how does it shuts down then if not by own?

This phenomenon mentioned by OP is by design and there isn't anything wrong.

[skb1811]

Completely normal, even my granddads 2009 Logan 1.4p did this, used to confuse him sometimes, until he read the owners manual and figured that it does that to cool the engine once it's shut down, iirc it's usually to cool down the engine and coolant to a preset temp

[black_rider]

But how does the fan help in cooling down the engine if the water pump is not running? From what I know, water pump runs on accessory belt, and it can't function without the engine running. Or do some cars have electrical water pumps?

[NomadSK]

Originally Posted by black_rider

But how does the fan help in cooling down the engine if the water pump is not running? From what I know, water pump runs on accessory belt, and it can't function without the engine running. Or do some cars have electrical water pumps?

Natural convective heat transfer takes place from the fluid near the engine (Hot) and the fluid in the radiator (Cold), when car is switched off. Hence Hot fluid is pushed to the radiator and cold fluid takes its place around the engine block, creating a flow circuit/circular loop, bottom line coolant fluid flows from hot to cold region which this radiator fan dissipates (Forced convection) the heat by convective cooling across the radiator. And in milder/colder weather condition, this could be achieved by natural convection (without fans)

Meaning there is a convective coolant flow even after the engine is switched off, definitely small as compared to the water pump. Also, that's why you have upper and lower radiator hoses.

For more clarity heat a bowl of water, the bottom hot water will start moving up and the cold water will start coming down, till equilibrium (Boiling Point) is reached.

[applegrew]

Originally Posted by Night Raven

Don’t worry, I have experienced the same few times in my Compass petrol. It was after driving the car in first gear or under load for sometime and turning off the engine immediately without idling. It shuts off by itself after sometime.
Did you check the engine temperature or coolant temperature in MID while this was happening? Do check the coolant levels also.

I missed to take note of the temperatures. Will do next time.

[ObsessedByFIAT]

That's pretty normal! I used to see the same behaviour on my 2003 Fiat Palio ELX petrol and sometimes it happened on Renault Triber and Kwid.

The fan runs a little longer after the engine is shut off to cool the engine down.

[GTE]

If the radiator keeps running after your car comes to a halt you are in big trouble, that would be the first time I have heard of this. If however your fan stays on much longer than normal, check the fins on the radiator & condenser. You can possibly take it to a petrol pump that has a service section with a powerful compressor use the air hose to blow compressed air from the engine side of the radiator and check if loads of dust comes out of the front. That could solve the problem.

[svsantosh]

Originally Posted by applegrew

Is this is a feature or a bug?

Normal, dont worry.

Originally Posted by black_rider

But how does the fan help in cooling down the engine if the water pump is not running?

Originally Posted by NomadSK

Natural convective heat transfer ...Hence Hot fluid is pushed to the radiator ...creating a flow circuit/circular loop\.

Brilliant answer That is the exact purpose of the high speed fan running after the engine is turned off. One addition notably to be mentioned here is the thermostat remains open because the temp is above the cut off point hence water flows through the thermostat and into and out of the engine block.

Originally Posted by GTE

If the radiator keeps running after your car comes to a halt you are in big trouble,]

Why, could you elaborate? Are you hinting at a overheating/loss of coolant issue? Or a faulty temp sensor/thermostat issue? I think the OP case is a natural case of hot engine (95'C+) and may be he is stopping the car immediately after a bumper to bumper with full AC in Hyderabad summer. I think it is 40'c these days there.

PS - This high speed fan running after turning off the engine was seen back in early 2000s, IIRC the Fiats/Opels/Daewoos had it. I am pretty sure all the Germans even the VW had it in India.

[itwasntme]

Originally Posted by applegrew

Heat wave has been going on in Hyderabad for quite some time now. Also recently we completed a trip to Bangalore and Coorg, it never happened then.

On long highway drives most engines run cooler as compared to when in traffic. In the former, the load is steadier and the speeds ensure a significant amount of fresh cool air is forced through the cooling fins.

In my 330i, the Active Grill technology actually keeps the front grill closed until the engine temperature reaches a particular point, after which it automatically opens.