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-   -   Do all Turbos require idling before shut-off? (https://www.team-bhp.com/forum/technical-stuff/17463-do-all-turbos-require-idling-before-shut-off-7.html)

My routine on a Skoda Laura Diesel 2 Ltr CR:

At startup i do not idle (manual says best to get engine warmed up as soon as possible, hence do not idle simply drive away albeit gently). However during the initial few minutes of drive I am careful not to exceed 2000 RPM atleast until the temp reaches 75% of its stable value. This car takes as much as 6 minutes to completely warm up when driven gently!

On stopping I always make sure to idle for 1 to 2 mins depending on how long or aggressive i have been driving.

The above is inline with the user manual recommendation. Better stick to it rather than have regrets later :)

I do not idle the engine at startup but i make sure to drive with a very light foot until the engine reaches optimum operating temperature. Before stopping the engine i let her idle for around 30 seconds, in the mean time i collect all the stuff i need to carry from the car.

I drive the car with a light foot majority of the times, this not only helps FE and but also extends Engine life though slower rate of wear and tear.

Thanks for bringing this point up. I have basically never owned any diesel car and recently purchased a Laura TSI. I was totally unaware of this precaution required for turbo charged engines. Guess this applies to turbo charged petrols as well?

My laura manual says "you should not switch the engine off right away at the end of your journey after the engine has been operated for a lengthy period at high loads but should be allowed it to run at idling speed for about 2 minutes. This prevents any accumulation of heat when the engine is switched off."

I thought I had read the manual thoroughly form beginning to end. DOn't know how I missed it. :Frustrati

@Santosh

This is the exact statement that confounded me. Statement does not provide any clue whether it is addressing the potential issues with turbocharger or engine n general.

The temperature gauge in Yeti stabilises near 90 degree and doesn't budge from there regardless of the operating conditions. I've noticed that climbing hills or traversing super-heated roads in Rajasthan. Or just driving around in 4 degrees cool of winter.

Further "lengthy periods at high load" is a bit puzzling. It is substantially open to perceptions and interpretation.

I do idle the engine for 30 odd seconds before turning off. I rarely push the RPM beyond 1700 except for a couple of seconds when accelerating.

I don't think you have anything to worry.

I think the fan takes care of the engine heat in general as it runs for a few minutes (if necessary) even after switching off the engine.

You are right about the temp guage. It hardly moves from that position.

I was a little concerned, since the TSI engine is so addictive, it just begs to be driven hard. ;)

Hi Santoshbhat,

From what i have read, in general, the petrol turbos spin and heat much more than the diesel. So if I were you, i would certainly idle for a minute or two depending on how hard the drive was before turning it off. Remember these are complex beast and deliver only when handle with care. The last thing one wants is a blown turbo. Yes i do acknowledge with the modern synthetic oils the risk of oil cooking in a hot turbo and eventually destroying it has dramatically come down. But better safe than sorry. Happy motoring!

+ 100

This is what I have been practicing. Before driving off, I try to let it idle by slowly moving few meters w/o any input from the accelerator pedal (if there are occupants, if no occupants, I idle) I do not switch on the A/C too for first 1 minute, the fan helps.

While coming to a halt, I switch off the A/C while idling, switch off the ICE and start looking around for few things (again, if there are occupants & getting rest less lol:) sip water (almost 30 secs over) and then I get off, take all papers, lappy bag and then at last, switch off.

There is no temp gauge in my car and the brilliant people at Ford have provided just one fan for both the engine & A/C

@Sheel, I am glad i jumped into this thread, really need to learn these tricks from you and adapt myself as i recently brought a Indica TDI from my friend and i am already feeling embarrassed with idling stuff everytime i take the vehicle out.

Thats the best way.
Start the car, and then start moving without acc. pedal input. Buy the time you get out into the open road, you would have idled for 30 seconds or more.
you could start the engine, as soon as you get into the car, and then wear your seatbelt, lock doors etc., etc., that buys you 15 seconds :)

@SushilBajpai; The water temperature gauge will not tell you what is happening. Idling allows the turbine to slow down and then oil to circulate and cool down its bearings. I am wondering what Mahindra's are doing with their vehicles with Smart Start-Stop.

Excellent thread. I for one religiously follow idling at startup and shutdown. Can someone shed light on what would/can be termed as overdoing it? Say for a 3.0L Diesel Turbo?

I do 60 seconds as a minimum, but sometimes I let the idling cross 90 and 120 as well.

Something else to consider is the fact that 'cold start' is the most polluting period in any journey. Rather than stand still for 30-60 odd second and spew these emissions, its advisable to start rolling with a light foot on the accelerator. This is the standard recommendation for most cars and SUVs these days, not just on account of emissions bust also on account of improved engine \ turbocharger designs I suppose. With regards to idling before stopping - I guess its dependant on how hard the vehicle has been driven prior to stopping, as many have suggested in this thread.

I roll immediately after starting, or almost immediately. With very little accelerator input, but enough to not lug or strain the engine. Around the 1.7 - 1.8k mark.

Using 0W40 oil to help with colder conditions which start in Delhi next month. The startup turbo clatter has disappeared after changing the default Selena to Mobil 1.

For last 3 minutes, I drive very gently as I'm anyway heading to the parking in my housing complex or my office basement.

I am surprised to know this as in case of marine engines it is exactly opposite. Earlier on there were water cooled turbochargers however offlate I am just seeing all uncooled turbochargers. This might be because of umpteen number of cases of corossion holes in turbo casing causing water to find way to cylinders and resultant crank shaft slips.

Do automotive engines have a separate oil supply pump?stupid:

Looking at 12V battery source I guess no. In that case there must be an attached lube oil pump. This 1 min of post start idling would ensure that dry turbocharger bearings get well lubricated prior turbo starts rolling. (I am assuming that the automotive turbochargers do not have there own lube oil sump. In marine engines both types i.e. engine sumpoil lubricated and dedicated sumpoil lubicated exist. Dedicated sumpoiltype are invariably water cooled)

And on the same count, the turbo continues to run due to inertia for sometime even if car starts idling. As the idling time increases turbo rpm drops to safer limit where bearing won't be affected by sudden loss of oil supply as switching off engine would switch off lube oil pump too. This might be the cause pre stop idling recommendation.

Apologies for going little :OT but it might be of some interest to a few.
In marine 4 stroke engines which emmitt black smoke, read emmissions, during idling and low load operations there is a system called jet-assist whereby compressed air is injected over turbine blade to give it a boost to run at higher RPM. This causes enhanced air supply to engine and hence smoking is taken care of. This off course is automatic read load dependent.

Rgds.

I'm sure you mean compressed air is injected at the compressor wheel, not turbine wheel!