[applegrew]

Originally Posted by svsantosh

Normal, dont worry.




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.



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.

Today my driving conditions where forgiving compared to yesterday and I could see the coolant temperature hovering around 88C. When starting the car it sometimes shot to 90C momentarily. Today the fans turned off normally. So it is possible that it had shot beyond 95C yesterday. And yes I had turned off the car without idling.

[GTE]

Originally Posted by svsantosh

Normal, dont worry.

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.

Why, could you elaborate? Are you hinting at a overheating/loss of coolant issue?

No, because then he would have to go & search for the radiator.

[AMG Power]

Most manufacturer manuals suggest keeping the engine idling for two minutes after a stressful drive - read stressful as city drives, hills, hot ambient temperatures, a lot of redlining, stop and go traffic etc. This is for the higher temperature levels to drop.

Additionally, newer engines have a tendency for the fan to come on more often as friction levels are relatively higher before the engine is run in. Which is also why run in periods have a lower rpm / speed suggestion.

Next time adopt the above practice before switching off your engine - the fan wlll not come on.

[svsantosh]

Originally Posted by applegrew

And yes I had turned off the car without idling.

Practice a short 15-30 second idling before turning off any NA/Turbo/Petrol/Diesel/Gas powered car. It surely helps to cool down things by a great margin.

OT - I practice end of drive idling without AC/Fan/Audio/Headlights and up power windows too, this way I ensure the battery charges up a little for the next day start too.

[GTE]

After cars switched to alternators from dynamos switching on or off the ac, fan, lights etc makes no significant difference to the battery charging.

[AshwinRS]

Originally Posted by 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.

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?

Hi Applegrew!

I am a Jeep Compass owner - 2021 Diesel Manual. This is a normal. This happens when you turn off the car in the middle of the DPF regeneration cycle - it does not matter how long the car was driven for from the last ignition. The DPF regeneration cycle normally happens every 150 to 200Kms depending upon your driving conditions. You will also notice that this doesn't happen every time you turn off the car.

When the DPF regeneration cycle is happening you will notice: (1) the loud fan - full blast; (2) jerky throttle response; and (3) sudden drop in fuel efficiency. In my case, the DPF regeneration cycle lasts for about 5 to 6kms of normal drive after the fan has started. So, during your long highway drives, you won't realize unless you keep a keen eye on your fuel efficiency.

If you turn off the car in the middle of the DPF regeneration cycle, it gets reset and might happen again within 50kms of next drive. So, let the fan run - it will switch off automatically.

I am given to understand that we may say it is a feature because the engine requires more cooling when the DPF regeneration cycle is in process.

Hope this settles your concern!

Disclaimer: I am not a technical guy - these are just my observations after driving my Jeep for approx. 53k kms in 2.5 years

[Jeroen]

Originally Posted by svsantosh

OT - I practice end of drive idling without AC/Fan/Audio/Headlights and up power windows too, this way I ensure the battery charges up a little for the next day start too.

When you have a good battery and a good normally operating alternator, there is absolutely no need to do so. The alternator has more than sufficient power to top up the battery fully, even with AC and everything else switched on. Even after a short drive!

If you feel your battery doesn’t get charged sufficiently during driving you need to get it checked, because it should. You need a proper battery load tester.

But as a rule of thumb as long as your alternator warning light is not coming on, the alternator is actually charging the battery.

Jeroen

[applegrew]

Originally Posted by Jeroen

When you have a good battery and a good normally operating alternator, there is absolutely no need to do so. The alternator has more than sufficient power to top up the battery fully, even with AC and everything else switched on. Even after a short drive!

If you feel your battery doesn’t get charged sufficiently during driving you need to get it checked, because it should. You need a proper battery load tester.

But as a rule of thumb as long as your alternator warning light is not coming on, the alternator is actually charging the battery.

Jeroen

Actually only last month I had an incident where the car's battery lost complete power in one night. It is detailed here (6-month old Jeep Meridian loses 100% battery charge in one night). The reason for that is still unknown. I was thinking maybe this is what might have happened at that time.

[chiekennugget]

Our MG Gloster does the same thing and this is what the instruction manual says:

[suryaj1990]

I have noticed this in most of my vehicles. My Skoda Yeti did this after a strong sprint, the electric MG does this along with circulation of coolant through its pump. But I guess for engines running without an electric fan do not have any such option. My Innova nor my Trailblazer do this even after aggressive use or high temperatures

[jessie007]

The fan keeps running after engine turning off, even in the humble Nano with a tiny engine. But understandably, since the engine is in the rear with not as much air flowing through the radiator (as in a front-engined car). In summers when AC is also used, the fan runs often, after the engine is turned off - feels the car is still alive!

[manishk123]

Happens on my BMW when I park after some aggressive driving. I was told by the dealer that it's the Turbo discharging.

Ideally Turbo engines should be allowed to idle a minute or two before you turn the engine off.

[jagdish_ker]

Still remember when I was learning to drive, I was taught not to switch off the engine (it was a Maruti Zen) if the radiator fan was running. I believe this was based on the fact, that cars were not much electronic controlled those days to run the fan once the key was removed. If I come across this, I would assume this is normal and intended by the manufacturer. It doesn't harm if it stops in a minute or two.

I have read somewhere a few electric cars do the same to cool the battery if it gets hot beyond a threshold. Not sure of the authenticity of this though.

[sanjeevs]

This is not a normal phenomenon at least for the older generation cars. Even if this feature is given for the newer generation cars, radiator fan running for additional minutes will have very little or no desired effect on the engine cooling effect in practical terms and at the same time draining the precious power from the battery if it is designed that way.

[drsnt]

I had seen this in my Fiat Uno and Linea T jet both. Fiat has this fan running feature even after the engine is switched off.