[phynix123]

Its not required. I am sure that my car's radiator fan continue to run for a few seconds even after turning off the engine and removing the keys. It cools itself by doing that. So never had to worry about cooling down the engine even on a few occasions when I drove more than 600 kms.

[autodoctor]

It is a very good Question and normally we all think it should be ok and guess a lot of things.

I agree with lots of comments above.

The thermostat (modern cars can have e-thermostats) will make sure the engine cooling fan(non the A/C fan) is triggered @ optimum temp (usually~85-90 C) measured from the coolant circuit, hence called as engine temp. And you normally see that in you dash board.

Like said above, bumper to bumper traffic is the 'best' scenario for a car to over heat (if at all). They key is to keep an eye on the temperature gauge and it should stay 'normal'.

On a normally aspirated car (i.e Non turbo-ed, Non super-charged), the best thing to do if you are stopping the car for more than 2 minutes, is to switch off the engine.

Cars can 'heat soak' after a highway drive or a hot day drive. On a high way drive, the wind is helping the cooling system to transfer the heat. when you stop the car it is loosing the flowing wind. So the heat from the engine will spread across as you stop.
Hence, Like a friend mentioned, yes it is a good idea to let the fan run, if it kicked in. But if you are in a hurry, its OK if you don't do it. Some cars will run the fan for few minutes even if after the keys are removed from the car (depends on manufacturer and how hot was your car).

These are the facts and remember people are different and petrol heads (like most of Us) will do lots of things which 'normal' people wont agree.
What i tend to do is, if i am new to the car, i do open the bonnet and check it out or let it 'cool'. But once i got used to the car (over the time) i just use my common sense to judge my actions according to the situation.

The key thing to remember is understand the basics and use the info. available to you (eg: your temperature gauge and/or smoke )


Hope it helps you.
Have a Good Day.
Drive/Ride Safe.

Kannan.

[proxax]

I've never done this once in 16 years of driving an automobile. I recently drove from Chennai to Vadodara. Day one was Chennai-Pune, engine was running for approximately 21 hours (4 hours worth breaks, where engine was idling). No overheating.. Having coolant and engine oil levels checked can help. Having driven a Maruti 800, Indigo and Skoda Rapid across India, I can assert my opinion; modern cars do not need the bonnet-raising treatment.

[ashis89]

I have covered 1200kms in 18hrs in my WagonR and never faced a glitch anywhere. I just made sure that I let the engine idle for a couple of minutes whenever I was to turn off the engine for longer breaks (for short breaks the engine was idling). This ensured that the fan was running.

[Vitalstatistiks]

Is this answer (popping the hood not required) universally applicable to all types of engines? Diesel as well as petrol? What about high torque generating machines, like trucks or JCB?

[Skyline_GT]

Originally Posted by Vitalstatistiks

Is this answer (popping the hood not required) universally applicable to all types of engines? Diesel as well as petrol? What about high torque generating machines, like trucks or JCB?

Yes any modern automobile engine be it a diesel/petrol is designed keeping the heat factor in mind. Every part inside the hood is made of materials that can withstand the kind.Even decade old cars(Esteems/Sumo) can do long distances just fine without need to have their hoods opened. As long as the vehicle and its engine is well maintained and has its oils topped up routinely there's hardly any reason to pop up its hood. However the same cannot be applied to vehicles of much older vintage.
Regarding the trucks most of which are those decade old (TATA's 2515/407 models) i have observed most truckers driving with their hoods partially opened to let the relatively colder outside air keep the engine heat in check. Same can be observed on InterCity/InterState buses (barring the Volvo's) driving with their hoods partially opened. Due to the position of their hoods which is below the windshield mostly between the headlights they can afford to drive with their hoods open. Unlike car hoods that hinder with driver's visibility when opened.
I have no knowledge about the JCB's thou.

[mayankk]

I have earlier had cooling issues in my fiesta, so whenever we stop for lunch after driving 4-5 hours, I do open up the hood. But this is only because of aforementioned issues. Nothing like hill air to cool a car.
When delhi hit 45/47 some time back, I used to park the car in the garage after a 40 km mostly bumper to bumper drive, the fan used to run for almost 3-4 minutes, before shutting off. So, definitely a help in my case.
But I can understand, that cars which have never thrown up a scare, its not necessary. I do it just cos I am wary.

[pdma]

While I totally agree that raising the hood is not needed to cool the engine, somehow I have developed a habit from many years to raise the hood when ever we take a break on long drives. A dash of abundant fresh air will anyways not harm in my opinion. I do make it a point that the hood is open only when the car is visibly parked in close proximity from the table we take for the break.
I admit that there is no visible improvements in performance or any other manner by following this practice, but as as I said it is more of a personal choice where I feel the key components in the engine would feel better with some cool air (something like how we feel relaxed when we get that feel of fresh air across our face after you step out of the gym ).
I know it is a mechanical element but still, I feel for it .

Cheers,
pdma.

[tsk1979]

Normally its not needed, however at one time I did that. The car would have cooled without it too, but I did not have the luxury of time. The car needed to cool fast. Why?
Well the altitude was almost 19000 feet, and while doing the last 1km to Marsimik La we had to go up in Low range 1st-second gear. Due to lack of air density, she overheated and went into limp mode.

We somehow reached the top, opened the hood, and then poured some water on the radiator. We only had 15 minutes window, as it would have been dangerous to stop there for longer.

The hood up picture

[rr_zen]

Originally Posted by phynix123

Its not required. I am sure that my car's radiator fan continue to run for a few seconds even after turning off the engine and removing the keys.

Are you sure the radiator fan continues to run even after turning of the engine and removing the keys ? What I have witnessed is that since the radiator fan runs on the battery, once the ignition is switched off, the fan switches off too. Which car are you referring to here BTW ?

Originally Posted by tsk1979

Normally its not needed, however at one time I did that. The car would have cooled without it too, but I did not have the luxury of time. The car needed to cool fast. Why?
Well the altitude was almost 19000 feet, and while doing the last 1km to Marsimik La we had to go up in Low range 1st-second gear. Due to lack of air density, she overheated and went into limp mode.

We somehow reached the top, opened the hood, and then poured some water on the radiator. We only had 15 minutes window, as it would have been dangerous to stop there for longer.

I agree. I do the same thing on my trips to Tirumala. Since the car is pushed while climbing up the hill I prefer to prop the hood open upon reaching the destination. While I understand that this is not required for the new age vehicles, I have been practicing this for a long time now on my long drives as it doesn't hurt to do the same.

[Jeroen]

Originally Posted by rr_zen

Are you sure the radiator fan continues to run even after turning of the engine and removing the keys ? What I have witnessed is that since the radiator fan runs on the battery, once the ignition is switched off, the fan switches off too. Which car are you referring to here BTW ?







.

I'm not sure about the Indian markets but I can assure you that on many modern cars the electric radiator fan (can) remain on after switching of the engine.

In fact, it could happen that the fan switches on some 10-30 seconds after you switch of the ignition. You will see this mentioned in the owners manual. You need to be aware of in case you open the hood to check for instance liquid cooling level. You don't want your hands or tools anywhere that fan!

On a modern car, killing the ignition doesn't kill all electrical circuits.

Jeroen

[Lobogris]

Originally Posted by proxax

I've never done this once in 16 years of driving an automobile. I recently drove from Chennai to Vadodara. Day one was Chennai-Pune, engine was running for approximately 21 hours (4 hours worth breaks, where engine was idling). No overheating.. Having coolant and engine oil levels checked can help. Having driven a Maruti 800, Indigo and Skoda Rapid across India, I can assert my opinion; modern cars do not need the bonnet-raising treatment.

Why did you keep your engine idling for 4 hours during breaks? Was it for ac use for some passengers left in the vehicle? It is a good idea to get out and stretch for at least 10 minutes after a long drive and the engine can be switched off for a break during that time as well. If nothing else, you reduce pollution and save fuel.

[joelchandra]

Originally Posted by rr_zen

Are you sure the radiator fan continues to run even after turning of the engine and removing the keys ? What I have witnessed is that since the radiator fan runs on the battery, once the ignition is switched off, the fan switches off too. Which car are you referring to here BTW ?

Volkswagen has this feature in it. I have seen my friends Vento do this a lot of times when we reach a destination after a long highway drive. I was taken back the first time but i was told that this feature exist.

[Roomy]

Originally Posted by joelchandra

Volkswagen has this feature in it. I have seen my friends Vento do this a lot of times when we reach a destination after a long highway drive. I was taken back the first time but i was told that this feature exist.

Even my Fabia has it. A very neat feature considering there may be situations where you'll turn off the engine without allowing for enough time to cool off.
But, what happens to the turbo? Is there any fan specifically for that?

[phynix123]

Originally Posted by rr_zen

Are you sure the radiator fan continues to run even after turning of the engine and removing the keys ? What I have witnessed is that since the radiator fan runs on the battery, once the ignition is switched off, the fan switches off too. Which car are you referring to here BTW ?

Yes sir, As already mentioned in the previous post, I am pretty sure that the fan continues to run even after turning off the engine (even removing of the keys). However, it runs only for a few seconds until heat dissipates.
The car i am mentioning here is chevrolet spark.