I think it is recommended to switch off the AC before switching off the engine.![[:)]](https://www.theautomotiveindia.com/forums/images/smilies/Smile.gif "Smile [:)]")
Guide: How To Drive and Maintain a Diesel Car?
- Thread Starter raj_5004
- Start date
As told to me by a technician, years back.
Switch off ac before stopping the engine, and let the blower run for a while. Why?
Because if not done so, the chill in the air passages will condense moisture and will remain clogged there. This is not healthy and would have bad effect on cooling. Sounds correct!!
Switch off ac before stopping the engine, and let the blower run for a while. Why?
Because if not done so, the chill in the air passages will condense moisture and will remain clogged there. This is not healthy and would have bad effect on cooling. Sounds correct!!
A super duper stupid query:-
From the day i am driving I have been taught to idle any car for at least 20-30 seconds before moving it for the first time in the day,why is it so?Amazingly I know what to do but don't really know why?
Secondly,if we don't do it,then what can be the technical issues we may have to face?
From the day i am driving I have been taught to idle any car for at least 20-30 seconds before moving it for the first time in the day,why is it so?Amazingly I know what to do but don't really know why?
Secondly,if we don't do it,then what can be the technical issues we may have to face?
I think the first thing,the idling is done to warm up the engine.I think this is not compulsory for modern day engines but still I think some follow it in cold countries.But I read in one article that idling is not a good thing to do and is not the best way to warm up the engine.
I don't know whether turbo charged engines requires idling before moving.
I don't know whether turbo charged engines requires idling before moving.
You might call it a super stupid query. But its very important.. The engine will show the results in the long run (idling and not idling cases). Engine has so many moving parts. And these parts bear the load of moving car. The load bearing parts (piston pin, crank pin, crankshaft and respective bearings, etc)need to be lubricated. When the engine is started, the lubrication just starts. If we start moving at same time, we are initiating more wear and tear as things are getting loaded in insufficiently lubricated conditions. Idling for 20-30 seconds lubricates parts well and engine is happy to rev. Thats it.
Yes warming up is also one of the important reasons.
Yes warming up is also one of the important reasons.
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I had enquired about this with the Volkswagen guy at the showroom & he said no problem in doing that for german cars! ![[confused]](https://www.theautomotiveindia.com/forums/images/smilies/Confused.gif "Confused [confused]")
okay. So what about switching off the AC just before switching the engine off? Maybe only a time gap of a second or milllisecond. I asked coz I always see my brother doing the same.![[frustration]](https://www.theautomotiveindia.com/forums/images/smilies/Frustration.gif "Frustration [frustration]")
its true to an extent I suppose. Its recommended only for diesel cars which has been in switched off position for about 24hrs or more! I do this often when the car has been in the shed for 1-2days.
okay. So what about switching off the AC just before switching the engine off? Maybe only a time gap of a second or milllisecond. I asked coz I always see my brother doing the same.
its true to an extent I suppose. Its recommended only for diesel cars which has been in switched off position for about 24hrs or more! I do this often when the car has been in the shed for 1-2days.
Diesel car or petrol car, or steam engine, lubrication is needed for all of them. So, its recommended for all
But I heard idling will lead to wastage of fuel.I also read read that it is better to keep the revs low for a few initial kilometers rather than idling.Correct me if I am wrong.
Well, that's indeed true. It surely needs a some wastage but its just for a few seconds.
As you have said, keeping the revs low can also work but its always better to keep it at idle position.
P.S : Revving up cold engines is not good. Its the same thing which is being told here!
As you have said, keeping the revs low can also work but its always better to keep it at idle position.
P.S : Revving up cold engines is not good. Its the same thing which is being told here!
Understeer is hitting the wall with your front end. Oversteer is hitting the wall with your back end.
Horsepower is how fast you hit the wall. Torque is how far you push the wall.
Buddy. This signature is quite educative.
Understeer, oversteer, horsepower and torque, all explained well!!!!![[lol]](https://www.theautomotiveindia.com/forums/images/smilies/Laugh.gif "Laugh [lol]")
Horsepower is how fast you hit the wall. Torque is how far you push the wall.
Buddy. This signature is quite educative.
Understeer, oversteer, horsepower and torque, all explained well!!!!
Thanks friends for the quick and easy replies.
Another query:-
I have seen a lot of bus/truck drivers that when they return back from any journey then before switching the engine off,they rev it quite high 3-4 times and then they turn it off.Any special reason behind it?
I don't do it,instead after returning I let my car idle once more for about 5-10 seconds and then switch it off.Any issue with this practice?
@Jihu:
Buddy you believe it or not but I was always confused in these terms and was never able to understand them clearly but then one day I read your signature and got it noted down(copyright issue it may be now)and form the verys ame day I have understood the concept quite well.Like this:-
Understeer:-Maybe front wheels aren't able to give the car direction due to any reason.Like what happens to many rear wheel drive SUVs on slippery roads when given sudden steering inputs.
Oversteer:-Drive a DZire and make it take a turn at high speed and you will understand it very well.![[;)]](https://www.theautomotiveindia.com/forums/images/smilies/Wink.gif "Wink [;)]")
About next two..no need to discuss...
Another query:-
I have seen a lot of bus/truck drivers that when they return back from any journey then before switching the engine off,they rev it quite high 3-4 times and then they turn it off.Any special reason behind it?
I don't do it,instead after returning I let my car idle once more for about 5-10 seconds and then switch it off.Any issue with this practice?
Understeer is hitting the wall with your front end. Oversteer is hitting the wall with your back end.
Horsepower is how fast you hit the wall. Torque is how far you push the wall.
Buddy. This signature is quite educative.
Understeer, oversteer, horsepower and torque, all explained well!!!!
Horsepower is how fast you hit the wall. Torque is how far you push the wall.
Buddy. This signature is quite educative.
Understeer, oversteer, horsepower and torque, all explained well!!!!
Buddy you believe it or not but I was always confused in these terms and was never able to understand them clearly but then one day I read your signature and got it noted down(copyright issue it may be now)and form the verys ame day I have understood the concept quite well.Like this:-
Understeer:-Maybe front wheels aren't able to give the car direction due to any reason.Like what happens to many rear wheel drive SUVs on slippery roads when given sudden steering inputs.
Oversteer:-Drive a DZire and make it take a turn at high speed and you will understand it very well.
About next two..no need to discuss...
Thanks friends for the quick and easy replies.
Another query:-
I have seen a lot of bus/truck drivers that when they return back from any journey then before switching the engine off,they rev it quite high 3-4 times and then they turn it off.Any special reason behind it?
I don't do it,instead after returning I let my car idle once more for about 5-10 seconds and then switch it off.Any issue with this practice?
@Jihu:
Buddy you believe it or not but I was always confused in these terms and was never able to understand them clearly but then one day I read your signature and got it noted down(copyright issue it may be now)and form the verys ame day I have understood the concept quite well.Like this:-
Understeer:-Maybe front wheels aren't able to give the car direction due to any reason.Like what happens to many rear wheel drive SUVs on slippery roads when given sudden steering inputs.
Oversteer:-Drive a DZire and make it take a turn at high speed and you will understand it very well.
About next two..no need to discuss...
Another query:-
I have seen a lot of bus/truck drivers that when they return back from any journey then before switching the engine off,they rev it quite high 3-4 times and then they turn it off.Any special reason behind it?
I don't do it,instead after returning I let my car idle once more for about 5-10 seconds and then switch it off.Any issue with this practice?
@Jihu:
Buddy you believe it or not but I was always confused in these terms and was never able to understand them clearly but then one day I read your signature and got it noted down(copyright issue it may be now)and form the verys ame day I have understood the concept quite well.Like this:-
Understeer:-Maybe front wheels aren't able to give the car direction due to any reason.Like what happens to many rear wheel drive SUVs on slippery roads when given sudden steering inputs.
Oversteer:-Drive a DZire and make it take a turn at high speed and you will understand it very well.
About next two..no need to discuss...
BTW,I thin even your petrol one is turbo charged.
Regarding the meaning of under steer,I think what it means is that the car don't steer as much as you want,like say when you turn left at a degree ,the car move left but not as much like you want it to be.
Here is the defintion of oversteer and understeer from wikipedia-"Understeer and oversteer are vehicle dynamics terms used to describe the sensitivity of a vehicle to steering. Simply put, oversteer is what occurs when a car turns (steers) by more than (over) the amount commanded by the driver. Conversely, understeer is what occurs when a car steers less than, or 'under' the amount commanded by the driver."
Understeer-In short loosing grip on the front wheels when going through a corner,quite common with our small city cars & also front wheel drive cars.
Over steer-In short is loosing grip on the rear wheels when going through a corner(had a long aggressive one in the Pajero once),usually the case on rear wheel drive cars when power is applied through a corner.
The idling is done to cool down the turbo especially after a long run,this should be strictly followed on petrol turbo variants as they run hotter than the diesels,some of the tuner cars(diesel & Petrol) have turbo timers which shut down engine after a set time,even if you have left the car.
Over steer-In short is loosing grip on the rear wheels when going through a corner(had a long aggressive one in the Pajero once),usually the case on rear wheel drive cars when power is applied through a corner.
The idling is done to cool down the turbo especially after a long run,this should be strictly followed on petrol turbo variants as they run hotter than the diesels,some of the tuner cars(diesel & Petrol) have turbo timers which shut down engine after a set time,even if you have left the car.
Okay. My humble two cents on the idling part:
1. Idling before staring off/cold start - The engine consists of many moving parts that are constantly rubbing against each other when the engine is started and till the time it is switched off. To avoid wear and tear due to this friction, these parts need to be lubricated (like the thin film of fluid between our eye and the eyelid- we do not feel any rashes while blinking our eyelids because of that fluid). This lubrication is done by the engine oil. In a four stroke engine, this engine oil is stored in an oil sump from where is is pumperd to various parts of the engine through various oil lines by means of an oil pump (in a two stroke engine,the oil is directly mixed to petrol and therefore lubrication srarts the moment that engine is started). Now obviously, the oil pump would take a few seconds to circulate oil to the moving parts of the engine after the engine is started. We also know that the faster the friction (which would occur if the engine id revved higher), the more the wear and tear of the moving parts. This is why one should wait for a few seconds (say, 30 seconds) before starting off in a cold engine scenario. Once the engine is switched off, the entire engine oil trickles down back into the oil sump, but this takes time. Ideally, if a vehicle has been given a halt of,say, 30 minutes or more, it shall always be good if the engine is idled for 30 seconds before moving off. For the same reason, one should not rev a cold engine. Drive sedately for a couple of kilometres and then, open up. Consider an engine like the human body. We warm up before starting to exercise, don't we? What happens if we start exercising vigorously without warming up properly? Cramps,sprains,muscle pulls,etc. Same happens to an engine. Isn't this lovely - this striking resemblance between the human body and a car. We have lungs, the car has air filter. We have kidneys, the car has oil filter, we have a heart, the car has cylinders, we have valves in the heart, the car has valves in the cylinder head, we have a nose, the car has an air intake. We have a mouth, the car has a carburetteor/Fuel injector. We have arteries and veins, the car has fuel/oil lines. We have an exhaust
,the car has an exhaust !!
2. Idling before switching off the engine: this is reqquired only for turbocharged engines. The turbo spins at speeds like 140000 rpm and so it requires lubrication till the time it has come to a halt. Coming to a halt from speeds of 140000 rpm requires some time. When we rev our cars to,say 5000 rpm, the tacho takes about a second or two to fall back to zero rpm, no? That is whi one should idle a turbocharged engine for a minute or so to allow proper lubrication of the turbocharger till the time it comes to a complete halt. Some turbocharged engines are fitted with a delay shutdown mechanism to facilitate this. However, if this becomes too much of a chore, one can alternatively drive one's car at a rpm range where the turbo doesn't start to spool (e.g. below 2000rpm for Maruti Swift, below 1500 rpm for Nissan Micra/Renault Pulse, etc) for about a minute before ending one's journey so that the turbo gets enough time to come to a halt before one stops and has to switch off the engine. To put this simply, drive your turbocharged car very slowly for about a minute before coming to a halt.
Hope this explanation puts and end to all idling doubts.
1. Idling before staring off/cold start - The engine consists of many moving parts that are constantly rubbing against each other when the engine is started and till the time it is switched off. To avoid wear and tear due to this friction, these parts need to be lubricated (like the thin film of fluid between our eye and the eyelid- we do not feel any rashes while blinking our eyelids because of that fluid). This lubrication is done by the engine oil. In a four stroke engine, this engine oil is stored in an oil sump from where is is pumperd to various parts of the engine through various oil lines by means of an oil pump (in a two stroke engine,the oil is directly mixed to petrol and therefore lubrication srarts the moment that engine is started). Now obviously, the oil pump would take a few seconds to circulate oil to the moving parts of the engine after the engine is started. We also know that the faster the friction (which would occur if the engine id revved higher), the more the wear and tear of the moving parts. This is why one should wait for a few seconds (say, 30 seconds) before starting off in a cold engine scenario. Once the engine is switched off, the entire engine oil trickles down back into the oil sump, but this takes time. Ideally, if a vehicle has been given a halt of,say, 30 minutes or more, it shall always be good if the engine is idled for 30 seconds before moving off. For the same reason, one should not rev a cold engine. Drive sedately for a couple of kilometres and then, open up. Consider an engine like the human body. We warm up before starting to exercise, don't we? What happens if we start exercising vigorously without warming up properly? Cramps,sprains,muscle pulls,etc. Same happens to an engine. Isn't this lovely - this striking resemblance between the human body and a car. We have lungs, the car has air filter. We have kidneys, the car has oil filter, we have a heart, the car has cylinders, we have valves in the heart, the car has valves in the cylinder head, we have a nose, the car has an air intake. We have a mouth, the car has a carburetteor/Fuel injector. We have arteries and veins, the car has fuel/oil lines. We have an exhaust
,the car has an exhaust !!2. Idling before switching off the engine: this is reqquired only for turbocharged engines. The turbo spins at speeds like 140000 rpm and so it requires lubrication till the time it has come to a halt. Coming to a halt from speeds of 140000 rpm requires some time. When we rev our cars to,say 5000 rpm, the tacho takes about a second or two to fall back to zero rpm, no? That is whi one should idle a turbocharged engine for a minute or so to allow proper lubrication of the turbocharger till the time it comes to a complete halt. Some turbocharged engines are fitted with a delay shutdown mechanism to facilitate this. However, if this becomes too much of a chore, one can alternatively drive one's car at a rpm range where the turbo doesn't start to spool (e.g. below 2000rpm for Maruti Swift, below 1500 rpm for Nissan Micra/Renault Pulse, etc) for about a minute before ending one's journey so that the turbo gets enough time to come to a halt before one stops and has to switch off the engine. To put this simply, drive your turbocharged car very slowly for about a minute before coming to a halt.
Hope this explanation puts and end to all idling doubts.
Thanks Sam. All the doubts of idling issue have been sorted now. I try to keep this practice that you mentioned but sometimes in a hurry i forgot the idling and switch off the engine immediatly after journey. I will strictly follow these steps henceforth.