[gd1418]

Can I have more details on the above and where does one get it? Does this work for diesels?

Originally Posted by Boom Shiva

It's usually recommended to idle the car or get a turbo timer which does the job for you.

I'm not sure about your case...the only turbochargings I've dealt with are petrol related. I'm sure MB knows what it's doing though.

Thank you Sir, a very enlightening discourse on turbo function..Thanks again..

Originally Posted by Sideways

Just a few basics.

I am assuming we all know how turbos work. Contraption bolted onto the exhaust manifold. Exhaust gases turn turbine which is connected to compresoor with a shaft, anf therefore puts in more air, allowing more fuel to be fed into engine, resulting in more power and big smile on face.

Now, since the turbo runs on exhaust gases it gets seriously hot, very seriously hot and it is virtually impossible to keep them lubricated with any self contained substance, because it would have a tendency to dry out and seize. Therefore in order to keep temperatures down, oil (for lubrication also) and water are used to keep turbo's cooler.

I just had a word with a techie of T&T Motors the autho dealers for benz in Delhi. he said that it is good to idle before and aft for diesels in all makes irrespective of the brand..:-)

Originally Posted by GTO

Thanks for the replies, Steeroid & Sideways. To be honest, I am baffled as to why this practice is not recommended in the manual or by the Benz tech guys.

Butttttttttttt since I have yet to find a conclusive answer of "why not to idle", I take the safe way out and let her idle for atleast 30 seconds. Even my driver has strict instructions on the same. The only thing is...its a bit inconvenient and I was hoping to find a convincing answer that modern day diesels have a bypass for this.

Till then....will let her idle.

[EVO6]

I guess there is too much discussion being done on this.. I have a Diesel as well as a Petrol Turbo vehicle. In neither of the manuals is mentioned that u need to cool down. But as discussed in the topic yes the phenomenon of COKING happens which increases the Co-eff of Friction of the internals hence damaging the turbo.

I have done about 50000 km on my Diesel and 8000 km on the Petrol vehicle. The real requirement of a turbo timer is when a person is driving really hard at RPM's of 4000 for diesel and 6000 for petrol thats when the turbo becomes extremely hot. But general use driving is not so hard and hence the chances of COKING as negligible.

Also cars used for general driving are never run hard and then bought to a dead stop.. Generally while approaching a place of parking whether it is outside or home or office we drive the car extremely slow before coming to a halt and that time is about 15-30 secs. Hence sufficient cooling happens and hence no damage to the turbos.

Yes in case of a race day and modified cars with ECU remaps and Turbos running at extreme PSI's one need to have a Turbo timer or let the engine idle for 1 min. Let me specify RACEDAY or TRACKDAY or where one pushes the car to its limits..

Most regular sedans and cars run at about 10 PSI and thats hardly going to create a problem for the Turbo..
Its only when u decide to run a turbo at 20PSI which is designed for use at 10PSI then the problem might happen..

My Petrol turbo initially running at 10 PSI now is churning about about 18 PSI but yet no issues and when confirmed with the modification experts from UK, they also came up with the same thing that.. During regular URBAN driving its fine not to have turbo timer installed or even idle the car for 30 secs coz the New Gen lubrication system can handle these issues.. They have told me to be careful only during Track days or if i have really pushed my vehicle beyond limits..

Hope this would solve most of the mis-understandings.

Cheers

[Steeroid]

Originally Posted by gd1418

Sir, I beg to disagree on the above. I do not know about the new DICOR engine

I do, and it doesnt say anything. Its another matter that I always idle for a while on both start and stop, though.

[sumitdongerkery]

I own a skoda octavia but need to check the manuals regarding what skoda has to say abt this.. But just curious to know if turbochargers work on the exhaust gases, how can it be cooled by idling for sometime.

Guys!!!! please don't jump at me if it is silly question. This topic is new to me..

[Mpower]

Originally Posted by condor

Mpower, your say your car is a petrol turbo. Do we apply the same practice to a diesel turbo?

Both diesel and petrol turbos work on the same principle, so yes its always better to cool down the engine after a hard drive. Just watch your temp gage and make sure its in the normal zone. Ideally an oil temp gage will help (a must with after market turbos)

[RedOne]

This is what the manual says about my turbo Landcruiser:

--------------------------------------
Normal city driving - idling not necessary.

High speed driving: 80kph/50mph idle for 20 secs, 100kph/63mph idle for 1 minute.

Steep mountain slopes or continued driving above 100kph idle for 2
minutes.

Never turn the engine off immediately after a heavy load.
---------------------------------------

I usually drive below turbo kick-in rpm for the last km or so and then idle as recommended above.

Gears,
Red-One.

[R.P.M]

Most of the TATA cars require idling for atleast a minute before starting and stopping. ( indica turbo, sierra turbo)

This is clearly mentioned in the manuals and stickers next to the ignition.

Even the ford endeavor has a sticker which asks you to idle the car before starting and stopping.

[hell_rider]

yeps...my indica tcic also has such a sticker.

[PmDaWg]

Here's the jist of cooling down a turbo. The need for a cool down procedure depends on how hard the turbo and engine is used, and whether or not the turbo is water-cooled. Old Generation Turbos only have Oil Feed Lines almost all New Generation Turbos have Old and Water Lines to keep the turbo cool as well as lubricated. I can tell you that Garrett's GT Turbo Line are Water Cooled. So its not necessary to have a Turbo Timer or to idle the vehicle before turning it off.

[v1p3r]

All common-rail Mercs come with GT series water-cooled BB turbos.

[GTO]

Also cars used for general driving are never run hard and then bought to a dead stop..

You have to see the long straight, leading up to my work parking space.

[Godfather]

Yep steer.. Its there to idle the vehicle for 30 seconds before shutting down.

Godfather

[headers]

Originally Posted by sumitdongerkery

I own a skoda octavia but need to check the manuals regarding what skoda has to say abt this.. But just curious to know if turbochargers work on the exhaust gases, how can it be cooled by idling for sometime.

Hi, The exhaust gases enter the turbocharger and spins the turbine at anything between 80,000 to 200,000 RPM...The turbines running at THAT HIGH SPEED needs to cool down..The base speed is much lower though..

And also as sideways mentioned..modern Turbochargers use self lubricated ball bearings which help in faster turbo build up..and of course a faster shutdown..

Idling for sometime will let the Turbos come back to base speed and hence it will make the turbos last longer. Its better to switch off then rather than "Rev the car and switch off" like some truckwallas do it

[shazikon]

Originally Posted by headers

Idling for sometime will let the Turbos come back to base speed and hence it will make the turbos last longer. Its better to switch off then rather than "Rev the car and switch off" like some truckwallas do it

This is not the real reason why you to idle for 30 secs before switching off. The turbo gets really hot because of high RPM at which it runs. Because of the high RPMS ( ~200,000 RPM) the bearing which holds the turbine gets superhot and even the lubrication gets very hot. The only way the ball bearings ( ceramic or steel) can cool down is from the oil it feeds directly from the oil sump of the crank. while the engine is running the oil is circulating through the inlet to the ball bearings fed by the oil pump. when you suddenly stop the engine after a hard run, the bearings are still super hot and not yet cooled down and the oil supply is cut off - no cooling. Prolonged abuse of the bearings will burn the bearings and cause turbo failure. This is the reason why it is advised to keep the engine running so that the turbo bearings are fed with oil from the oil pump. The engine should be running for the oil pump to work. To over come this problem, turbo timers are available which keep the engine running for specified amount of time even if you lock and leave.. the turbo timer runs the engine and switches the engine OFF after the specified time. thus keeping the turbo bearings lubricated and cool.

[whatcanthisbe]

what baffled me most abt indian turbos was this exact same issue and lack of the idle timer the PSI gauge and the EGT gauge.....