# How long do you idle before engine shutdown?



## IndyDiesel (May 24, 2015)

I have a gen 1; if I have been driving hard I will idle for a little bit, otherwise I shut off after I come to a stop. I generally do not worry about stuff.


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## Taxman (Aug 10, 2017)

I gently cruze at a steady uninterrupted 55-60mph for five miles, the last four miles mostly devoid of hills, then 5-20mph depending on road conditions for a half mile, then 5-10mph down my driveway for 100 yards. If at the end of all that the turbo is too hot for my oil, something is seriously wrong.


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## Tomko (Jun 1, 2013)

Gen1 CTD here. I have never idled down my engine at any time. Never had a turbo or oil-related problem in 71,000 miles. But I’ve always run a full synthetic dexos2 registered oil.


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## snowwy66 (Nov 5, 2017)

Being a semi driver. I usually turned the fan on. Usually meant turning the a/c on. To cool the radiator down. Which also cools the oil down. Which raises the oil pressure a little. I like to try to cool the oil down so the bearings will last longer. 

Semi's drive a lot of miles though and pulling 80,ooo pounds up the rocky mountain hills can really heat things up.


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## IPhantom (Aug 22, 2017)

I suppose the time used for parking (parallel) is sufficient, no?


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## JDH (Dec 24, 2014)

What difference is it if I shut it off when I pull in the parking spot or AutoStop does it?


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## snowwy66 (Nov 5, 2017)

JDH said:


> What difference is it if I shut it off when I pull in the parking spot or AutoStop does it?


It's a moot point for those of us with that feature. LOL


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## 91794 (Mar 25, 2015)

In summer driving i will try to idle a briefly at a highway cruise stop. It hasnt been a factor during this winters distance cruises especially at 0F temperatures. Turbo is not going to get too hot during winter. Heat soak is not a worry either ....


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## MP81 (Jul 20, 2015)

As long as you're not beating the living **** out of the car right before you're done driving, you shouldn't have to worry about letting it idle more than maybe a few seconds.


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## jblackburn (Apr 14, 2012)

JDH said:


> What difference is it if I shut it off when I pull in the parking spot or AutoStop does it?


Mine's a gasser, but I've noticed that if I flog it, then come to a stop soon after, it doesn't shut off.


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## snowwy66 (Nov 5, 2017)

jblackburn said:


> Mine's a gasser, but I've noticed that if I flog it, then come to a stop soon after, it doesn't shut off.


I've been trying to work on that method. It seems to be rather delicate though. Although I"m starting to think my autostop is broke. It hasn't shut off the last couple of days to work and home. And it's been above the 41 mark.


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## jblackburn (Apr 14, 2012)

snowwy66 said:


> I've been trying to work on that method. It seems to be rather delicate though. Although I"m starting to think my autostop is broke. It hasn't shut off the last couple of days to work and home. And it's been above the 41 mark.


Check out your battery voltage (when off).


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## snowwy66 (Nov 5, 2017)

jblackburn said:


> Check out your battery voltage (when off).


12.3 today. It's usually 12.2


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## johnmo (Mar 2, 2017)

I never worry about idling any amount of time before shutting down. The approach to almost every destination involves some low-speed travel. For example, the last eighth mile to my office is a 25-mph street that I usually coast in neutral. Before I even get to that it's most of a mile on a downhill to a traffic light that is red most days. I've spent enough time off the throttle at that point that I can't even imagine there would be a benefit to spending any time idling.


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## 91794 (Mar 25, 2015)

Coasting into highway rest areas works nicely to chill the turbo a bit... in 90 degree weather. Vero and new smyrna ... daytona bike week. Didnt see any diesel motorcycles however.


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## Barry Allen (Apr 18, 2018)

johnmo said:


> For example, the last eighth mile to my office is a 25-mph street that I usually coast in neutral.


Coast in gear. The engine doesn't offer much braking power (there is no throttle plate to choke off airflow) so you will be powering the engine with inertia. The engine will be coasting with no fuel injected for combustion, so you will be pumping cool air through the turbo to chill it prior to shutdown.


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## Merc6 (Jun 8, 2013)

snowwy66 said:


> 12.3 today. It's usually 12.2


What was the outside temps? Cold out I believe it suspends the event. There was a long anti Auto stop thread that the info shows up a few times.


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## snowwy66 (Nov 5, 2017)

Merc6 said:


> What was the outside temps? Cold out I believe it suspends the event. There was a long anti Auto stop thread that the info shows up a few times.


It doesn't work below 41 degrees.


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## Merc6 (Jun 8, 2013)

snowwy66 said:


> It doesn't work below 41 degrees.


 That's pretty much here right this second now.


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## johnmo (Mar 2, 2017)

Barry Allen said:


> Coast in gear. The engine doesn't offer much braking power (there is no throttle plate to choke off airflow) so you will be powering the engine with inertia. The engine will be coasting with no fuel injected for combustion, so you will be pumping cool air through the turbo to chill it prior to shutdown.


I understand how it works. I'm not really coasting it with cooling the turbo in mind. The grade is slight enough that lower gears will slow it down and higher gears tend to buck or lug to where fuel is probably injected to maintain idle RPM. Any extra cooling I might manage to scrape together is going to evaporate as soon as I have to pull away from the stop at the security gate. It's just not worth obsessing over.


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## 91794 (Mar 25, 2015)

Not worth obsessing but worth considering on my next drive across USA in summatime. 
Speed limits are much increased from illinois westwards , both written and unwritten.


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## Jacque8080 (Oct 31, 2017)

Barry Allen said:


> Coast in gear. The engine doesn't offer much braking power (there is no throttle plate to choke off airflow) so you will be powering the engine with inertia. The engine will be coasting with no fuel injected for combustion, so you will be pumping cool air through the turbo to chill it prior to shutdown.


This diagram makes it looks like there is a throttle plate. I have never looked for it at 8K on the clock.

http://gmauthority.com/blog/wp-cont...LH7-engine-Chevrolet-Cruze-Diesel-details.jpg


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## jblackburn (Apr 14, 2012)

Jacque8080 said:


> This diagram makes it looks like there is a throttle plate. I have never looked for it at 8K on the clock.
> 
> http://gmauthority.com/blog/wp-cont...LH7-engine-Chevrolet-Cruze-Diesel-details.jpg


Yep. Think it's just there to block off airflow when the ignitions shut off though.

Sent from my SM-G950U using Tapatalk


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## Sunline Fan (Jul 29, 2012)

At Lordstown a couple years ago, in an attempt to diagnose a strange noise, I had my hood open and had people listening as I moved back and forth at very slow speeds. Andrei walked over with his thermal gun and put it on the turbo. Revving the engine up just a little (say 1500 RPM) increased the turbo temps significantly. But as soon as I let off, they dropped very quickly. I don't recall the actual temps, but let's say 1500 degrees at 1500 RPM, dropping to like 400 degrees at idle. And it got to 3-400 degrees within like 10 seconds. Granted this is with a gas car, but you need very little cool down time with these small turbos. Having the car at idle and pulling into/backing into a parking space is probably enough time to cool it down, by the time you let off the gas, put it in park, and shut it down.

My dad has a diesel pickup with an EGT gauge. It can take a little more time to cool down in stock form, but with a freer flowing exhaust and an intake, it doesn't take more than 30 seconds. They say don't shut it down with EGTs over about 350. Idle EGTs will be around 350 with the A/C compressor on, around 300 with it off, so it cools faster if you reach over and shut it off. I've found when after towing, it will take a couple minutes to drop from 400ish down to 350 degrees. Keep in mind this is a truck with twin turbos though, so there's twice as much to cool.

I bet -J would love to have a twin turbo'd Cruzenmobile.


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