# Warming up and cooling down diesel



## farmallgray (Nov 28, 2013)

My cousin bought one of the first Dodge trucks with the Cummins engine and he has owned them ever since. He is very religious about letting his truck warm up for at least 5 minutes before going anywhere, then letting it idle and cool off for another 5 minutes before shutting it down. 

I don't agree with warming it up. I feel it is better for the engine and it will warm up faster under a slight load going up the road than sitting and idling. Now I do keep the throttle low and let it shift at lower RPM till it gets warmed up. I do think letting it run for a minute or two after coming off the road is a good idea on any turbo charged engine just to cool the turbo down. 

What do the rest of you diesel owners do?


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## boraz (Aug 29, 2013)

start it drive it park it

99% of the time, thats fine...

if i stopping at the top of a 5 mile long 15% hill, i'll let it idle a minute or two, but normal driving is fine.


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## titanman2789 (Oct 27, 2013)

For our Cruze diesels, just drive it like a normal car. I let it warm up a minute if it's cold out. Never more than 5 minutes though, and that was in -20f. 

The older Cummins trucks I know you do need to let them cool down before shutting off. Not sure about the whole warm up thing but I do remember specifically reading about idling after driving with the old 5.9. 1-2 minutes for city driving and 3 minutes for highway driving. Something about the turbo I believe

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## MilTownSHO (Oct 9, 2013)

This isn't like old turbo cars where some people had turbo timers to keep the oil from cooking in the turbo, besides that was really only a worry if you were beating on it right before shutting it off.

As far as warming it up, just drive it normal and try not to beat on it until it warms up, it will be fine.


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## Aussie (Sep 16, 2012)

On my diesel I still have a digital temperature readout and even on a 117C day it didn't change more than 2-3 degrees C, so I wouldn't be too concerned about overheating unless your gauge moves quite a bit higher than normal.


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## KpaxFAQ (Sep 1, 2013)

Aussie said:


> On my diesel I still have a digital temperature readout and even on a 117C day it didn't change more than 2-3 degrees C, so I wouldn't be too concerned about overheating unless your gauge moves quite a bit higher than normal.


You have a digital exhaust gas temp readout that came stock? That's awesome. 

As others have said no need for warmup/cooldown. You can throw those worries in the same pile we threw cold starts, black smoke, and clanky loud motors. 

The only exception I might make is if I were to tow with it, or like another poster said, drove up a long continuous steep grade for a long time. Then yeah, a minute or two of idle wouldn't kill anyone and you'll probably be fine if you didn't.


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## Aussie (Sep 16, 2012)

It is a digital engine temperature, I believe it has been deleted in NA and you only have the round dial. Climbing a steep grade makes very little difference to the engine at all.


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## titanman2789 (Oct 27, 2013)

KpaxFAQ said:


> You can throw those worries in the same pile we threw cold starts, black smoke, and clanky loud motors.


I got a good cold start video. No it's not like a 90s diesel but these are still diesel engines. They are not going to start right away like always when in extreme cold


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## KpaxFAQ (Sep 1, 2013)

Aussie said:


> It is a digital engine temperature, I believe it has been deleted in NA and you only have the round dial. Climbing a steep grade makes very little difference to the engine at all.


Oh ok, what the OP is worried about is extreme temperatures within the oil lubricated turbo can coke the oil on the bearings if the engine is just shut down abruptly after a heavy load.

Engine coolant temperature like you said rarely moves and cannot indicate anything related to this.


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## KpaxFAQ (Sep 1, 2013)

titanman2789 said:


> I got a good cold start video. No it's not like a 90s diesel but these are still diesel engines. They are not going to start right away like always when in extreme cold
> 
> 
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Well if it gets cold enough yeah... but for 99.9% of users cold weather is a NON-Issue in a modern CR diesel with proper winter blend fuel...It did not used to be the case was my point.


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## titanman2789 (Oct 27, 2013)

KpaxFAQ said:


> Well if it gets cold enough yeah... but for 99.9% of users cold weather is a NON-Issue in a modern CR diesel with proper winter blend fuel...It did not used to be the case was my point.


Yeah. The oil pan heater would have helped me out but nothing I could do. I did get a small puff of black smoke out of the exhaust on one really cold start. That was cool. 

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## Cruze2.0Diesel (Jun 30, 2013)

I let it run long enough to be sure oil is to the turbo before touching the pedal, it shouldn't be any time at all unless it has set for a week or more. I also let it spool down before shutting it off, very important if you just got off the highway, two minutes usually. I don't care what synthetic oil you run, it can still cook, try it in a frying pan against a conventional oil for fun. I hope you all understand that we are replacing modern turbos for oil consumption problems and worn bearings because people do not take care of them. Turbos have very tight bearing clearances and they obviously get very hot.


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## diesel (Jun 8, 2013)

I drive off right away but try to keep the RPMs under 3000 at least until the needle moves. On cool down, I am used to old school turbos, so I let it idle for a few seconds before I shut it off.


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## plasticplant (Mar 26, 2013)

diesel said:


> I drive off right away but try to keep the RPMs under 3000 at least until the needle moves. On cool down, I am used to old school turbos, so I let it idle for a few seconds before I shut it off.


Exactly what I do. 10K plus miles and zero issues thus far.


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## titanman2789 (Oct 27, 2013)

Cruze2.0Diesel said:


> I let it run long enough to be sure oil is to the turbo before touching the pedal, it shouldn't be any time at all unless it has set for a week or more. I also let it spool down before shutting it off, very important if you just got off the highway, two minutes usually. I don't care what synthetic oil you run, it can still cook, try it in a frying pan against a conventional oil for fun. I hope you all understand that we are replacing modern turbos for oil consumption problems and worn bearings because people do not take care of them. Turbos have very tight bearing clearances and they obviously get very hot.


I don't think this is the case anymore. If it were it would state so in the owner's manual. This is what I was getting at in the old diesel trucks. Cool down time is very important but I don't think it's so important in modern turbos. 

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## Cruze2.0Diesel (Jun 30, 2013)

titanman2789 said:


> I don't think this is the case anymore. If it were it would state so in the owner's manual. This is what I was getting at in the old diesel trucks. Cool down time is very important but I don't think it's so important in modern turbos.
> 
> Sent from AutoGuide.com Free App


The only difference is water-cooled turbo's vs. non water-cooled, and I stand behind letting it spool down before shutting off the engine. If you want to listen to someone who sells turbo's they say the same thing as you, but I know we are replacing current water-cooled turbo's for oil consumption problems and toasted shafts when they should easily be going 200k miles.


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## diesel (Jun 8, 2013)

If you ever poke around under the hood after a run, the turbo does not seem to radiate nearly as much heat as an older diesel or a gasoline car. I don't have any actual data, just holding my hand over it and feeling the heat radiate off it.


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