[itwasntme]

Originally Posted by Night Rider

I have a Dec-2014 Polo GT Tdi which is used sparingly (parked in the stilt) and till date it has clocked 1283 Kms. I have this practice of idling the car (every 10-15 days) till temperature reaches 90 degrees. Is this ok or should I discontinue this

Suggest you drive it for those 10/15 minutes rather than idle it. There are plenty of non-engine parts which will enjoy the weekly workout. Once the temperature reaches the operating level, drive back in a sedate manner, park the vehicle and idle for maybe 60 seconds before powering off.

If you're not around, maybe get a trusted relative or driver to do this?

[BigBrad]

Originally Posted by Night Rider

I have a Dec-2014 Polo GT Tdi which is used sparingly (parked in the stilt) and till date it has clocked 1283 Kms. I have this practice of idling the car (every 10-15 days) till temperature reaches 90 degrees. Is this ok or should I discontinue this

Here's what Polo's owner's manual (page #150) says:

[Jeroen]

Originally Posted by Night Rider

I have a Dec-2014 Polo GT Tdi which is used sparingly (parked in the stilt) and till date it has clocked 1283 Kms. I have this practice of idling the car (every 10-15 days) till temperature reaches 90 degrees. Is this ok or should I discontinue this

Idling an engine to bring the temperature up is just about the worse thing you can do to an engine. It will occur wear and tear notably on the cylinder walls and piston rings due to poor lubrication. In order to get maximum adherence of the pub oil against the cilinder wall it needs to be at the normal operating temperature.

So start your engine and avoid high revving and high loading of the engine. Please note that if you have a cooling liquid temperature gauge that is not the same as your oil temperature. Typically the oil temperature lags behind. So when your temperature gauge shows normal operating temperature it might take another 5 minutes of gentle driving before the rest of the engine and oil has reached normal operating temperature.

These effects become worse as the ambient temperature drops. It's different when the car has been sitting outside at 25oC compared to 0oC or even subzero.

Jeroen

[fiestarry]

A car's engine functions best when it is in its correct operating temperature. At idling, the engine is not loaded and will take a long time to reach that required temperature. When you start moving, the engine is loaded, combusts more fuel and reaches the temp much sooner.
Besides, running the engine when stationary, deprives the exhaust of the cooling air and heats it up quite a bit.
Also, at idling, because of poorer combustion as a result of sub optimal engine temp, the emissions will be higher. In developed nations this is a cardinal sin and hence the advice to move at once.

[Night Rider]

Thanks for your inputs. Took the GT for a long drive today morning till igatpuri on NH3

[fry]

With regards to the Ecosport's Ecoboost engine:-
Nowhere in the manual, is it stated that idling is required.

I believe "Ford have included the log exhaust manifold in the head of the 1.0L Ecoboost engine so heat soak is not an issue but requires 20-30% larger radiator. "

Any thoughts?

[alpha1]

Originally Posted by Jeroen

Idling an engine to bring the temperature up is just about the worse thing you can do to an engine. It will occur wear and tear notably on the cylinder walls and piston rings due to poor lubrication.

Hmmmm, so then:

a) why does the ECU direct the engine to first idle at slightly higher RPM (say 1100) and then settle down to lower (say 700) after some time? (acting like a choke on carburetted engines)

b) how does idling at 700 rpm differ from driving at 700 rpm? (Or what the particular idling RPM may be for a particular engine)

[Jeroen]

Originally Posted by alpha1

Hmmmm, so then:

a) why does the ECU direct the engine to first idle at slightly higher RPM (say 1100) and then settle down to lower (say 700) after some time? (acting like a choke on carburetted engines)

b) how does idling at 700 rpm differ from driving at 700 rpm? (Or what the particular idling RPM may be for a particular engine)

When starting a cold engine there are different things in play.

A cold engine is bad environment for good combustion and it is also increases wear and tear. What to do? First things first:

Just to keep it simple. First, you need to get the combustion going. Secondly, you need to get the whole engine up to normal operating temperature, including all liquids.


How to get proper combustion going?
To keep things simple this is how it roughly works: During a cold start, it's initially more difficult to get a good combustion, so the ECU dials in a rich mixture, essentially to compensate for poor fuel atomization at these lower temperatures. There are different ways the various systems go about this, but its mostly along a combination of increasing the injection period (more fuel) and or opening of the cold start injector. (just adds fuel). And usually there might be an idle valve in play as well. (more air).

As the engine, or at least the cylinder head starts warming up the ECU will dial down the extra fuel injection and thus reduces RPM.

You need those higher RPMs as during this relatively cold start, the petrol is a little more difficult to vaporize and ignite. Resulting in unburned fuel, which might create problems with your plugs So the higher RPM also ensure you flush everything out.

So from that perspective the function is very similar to that of the old choke. Only much more precisely controlled.

On most cars, unless really cold, the RPM's start dropping after a few minutes. Again, if you do this at idle it will take longer then when you drive of immediately.

You can check by yourself. Start you engine from cold keep it on idle and time how long it takes to return to normal idle. Cool the engine down, start it, drive away and let go of the throttle (press clutch or go in N) every 20-30 seconds to check the idle and you will see a reduced time compared to the first measurement.

By the time your idle RPM drops your engine is still far from properly warmed through and through. Depends a bit from engine to engine and on the ambient temperature. But on average at say room temperature (20oC) it could take well up to 10 minutes of modest driving to get the whole engine, the cooling liquid and all of the oil up to normal operating temperatures.

All the time whilst your engine is not at normal operating temperatures your engine will suffer from additional wear and tear. Notably the cilinder liners and the piston rings. To some lesser extent the bearings as well.

Modern engines are very efficient. Which means also means that when running at idle with no load, they actually generate very little heat. Diesels in particular. Again, don't take my word for it, you easily verify this yourself.

Start your engine from cold and measure how long it takes for the cooling liquid temperature to reach normal operating temperature. The oil temperature will easily lag several minutes behind.

Cool the engine down, start and drive away immediately cautiously. Don't floor it. You will notice that the cooling liquid will reach its normal operating temperature considerable faster. The oil temperature is still lagging behind, but again, it will reach it's operating temperature much faster too.

So essentially by not idling, but starting and driving away, thus loading up the engine a bit, and thus creating more heat, the whole engine heats up quicker and therefor the period of increased wear and tear comes down.

Most owner manuals that I have seen will advise you exactly this.
As a rule of thumb, cars that are used mostly for city driving versus cars that do mostly highways, it's the city cars that have more wear and tear at the same mileage. Not because city driving is harder on the engine, but because there have been more cold starts and that's what causes the most wear and tear.

Just as an afterthought; when you car doesn't' reach it's normal operating temperature, say a stuck thermostat, always have it seen to. It wont cause a problem immediately. But a 10 degree too low operating temperature over several thousands of kilometres will definitely show up and can be actually measured for wear and tear.

To the second part of your question. It's not so much the RPM that is relevant as the loading of the engine, because that determines the amount of heat generated and thus how quickly the engines reaches its normal operating temperate.

For obvious reasons you do want to avoid high RPM's during the period the engine is still relatively cold. But by increasing the load (i.e. drive off) you increase the heat transfer into the engine cylinder head, pistons, liners, cooling liquid and oil etc.

Trying to do it to quickly can cause two problems. Increased wear and tear as the lubrication was not optimal yet. It can also cause thermo shock type of phenomena, which can cause problems with say the head gasket, possibly crack the cylinder head even.

To summarize;
Don't idle. Start and drive off immediately. It will ensure your ignition/combustion cycle will become quickly optimised and it reduces wear and tear.

Jeroen

[alpha1]

Originally Posted by Jeroen

On most cars, unless really cold, the RPM's start dropping after a few minutes. Again, if you do this at idle it will take longer then when you drive of immediately.

You can check by yourself. Start you engine from cold keep it on idle and time how long it takes to return to normal idle. Cool the engine down, start it, drive away and let go of the throttle (press clutch or go in N) every 20-30 seconds to check the idle and you will see a reduced time compared to the first measurement.

Modern engines are very efficient. Which means also means that when running at idle with no load, they actually generate very little heat. Diesels in particular. Again, don't take my word for it, you easily verify this yourself.

Start your engine from cold and measure how long it takes for the cooling liquid temperature to reach normal operating temperature. The oil temperature will easily lag several minutes behind.

Cool the engine down, start and drive away immediately cautiously. Don't floor it. You will notice that the cooling liquid will reach its normal operating temperature considerable faster. The oil temperature is still lagging behind, but again, it will reach it's operating temperature much faster too.

So essentially by not idling, but starting and driving away, thus loading up the engine a bit, and thus creating more heat, the whole engine heats up quicker and therefor the period of increased wear and tear comes down.

I think you've nailed it. Thanks.
The key operative point being don't let the engine run at low temperatures, but also don't demand so much (in the process of heating it) becuase it is still at low temperature.

[srvm]

Originally Posted by Jeroen

...... To summarize;
Don't idle. Start and drive off immediately. It will ensure your ignition/combustion cycle will become quickly optimised and it reduces wear and tear.
Jeroen

Originally Posted by alpha1

I think you've nailed it. Thanks.
The key operative point being don't let the engine run at low temperatures, but also don't demand so much (in the process of heating it) becuase it is still at low temperature.

Thanks a lot, Jeroen & alpha1 for the detailed explanation. I could comprehend most of what you wrote.
Then I saw this in my car's user manual (I drive Zest Revotron with 1.2liter turbocharged petrol engine):





Back to confused state again

[ajayclicks]

Originally Posted by srvm

Back to confused state again

The best practice, IMO is to follow your instruction manual. If it asks you to idle the engine, do that by all means.

[Jeroen]

Originally Posted by srvm

Thanks a lot, Jeroen & alpha1 for the detailed explanation. I could comprehend most of what you wrote.
Then I saw this in my car's user manual (I drive Zest Revotron with 1.2liter turbocharged petrol engine):

Back to confused state again

Always go by what the manual says over whatever is said by anybody on the Internet! Another reason to actually read the manual!

[Sawyer]

For most people living in cities, starting slowly isn't a problem, the act of taking it out of apartment parking and getting to the road is as slow a drive as needed to wake up the car/turbo gently. The thing to make a habit of is shutting down turbo equipped cars on places like highways or outdoors parking, where waiting in the car with the engine idling is something to be remembered.

Driving back into apartment parking, where it is done at slow speed in narrow spaces usually provides the necessary idling time; some accelerator use isn't a problem because the important thing is that the turbo has to be idling while the engine is running - as it does at parking speeds.

The main thing to be aware of is stopping at the side of the road on highway drives, where it is easy to shut the engine off as soon as one pulls up to the side; it is important to not do that, but let it run for a time, so that the lubrication inside the turbo keeps going for some time with the turbo idling. This does not apply to non turbo cars, usually the petrol ones which can be turned off right away.

[alpha1]

Originally Posted by srvm

Thanks a lot, Jeroen & alpha1 for the detailed explanation. I could comprehend most of what you wrote.
Then I saw this in my car's user manual (I drive Zest Revotron with 1.2liter turbocharged petrol engine):


Back to confused state again

Actually you should not be.

What I inquired and Jeroen responded is the engine block only - which includes pistons, lube system, cylinders, valves etc.

What your manual refers to is SPECIFICALLY the turbocharger.
So what they are saying is that idle for 30 seconds after starting and before stopping to take care of the lubrication of the Turbocharger.

Turbocharger sits downstream on the exhaust side of the engine. Hence, it was not in the scope of my discussion.

[srvm]

Thank you folks. Got it now

Originally Posted by ajayclicks

The best practice, IMO is to follow your instruction manual. If it asks you to idle the engine, do that by all means.

Originally Posted by Jeroen

Always go by what the manual says over whatever is said by anybody on the Internet! Another reason to actually read the manual!

Originally Posted by Sawyer

For most people living in cities, starting slowly isn't a problem, the act of taking it out of apartment parking and getting to the road is as slow a drive as needed to wake up the car/turbo gently. The thing to make a habit of is shutting down turbo equipped cars on places like highways or outdoors parking, where waiting in the car with the engine idling is something to be remembered.

Driving back into apartment parking, where it is done at slow speed in narrow spaces usually provides the necessary idling time; some accelerator use isn't a problem because the important thing is that the turbo has to be idling while the engine is running - as it does at parking speeds.

The main thing to be aware of is stopping at the side of the road on highway drives, where it is easy to shut the engine off as soon as one pulls up to the side; it is important to not do that, but let it run for a time, so that the lubrication inside the turbo keeps going for some time with the turbo idling. This does not apply to non turbo cars, usually the petrol ones which can be turned off right away.

Originally Posted by alpha1

Actually you should not be.

What I inquired and Jeroen responded is the engine block only - which includes pistons, lube system, cylinders, valves etc.

What your manual refers to is SPECIFICALLY the turbocharger.
So what they are saying is that idle for 30 seconds after starting and before stopping to take care of the lubrication of the Turbocharger.

Turbocharger sits downstream on the exhaust side of the engine. Hence, it was not in the scope of my discussion.