how long do i need to idle

jason86

Marv
Dec 30, 2008
78
0
6
Sacramento, CA
damn mine would be at 400 in 5 seconds right after racing. i have my turbo timer set at 2 minutes but if i hit the brakes she shuts right off.
 

dmaxfireman

'Can do' kind of guy
Apr 8, 2007
2,329
1
38
CT
i normally shut down between 300-400 unless i've been racing, pulling or just pulled off the highway (truckstop) then at least a 5 min cooldown to eliminate of some of the heatsoak. has to do with static and dynamic temps
 

jason86

Marv
Dec 30, 2008
78
0
6
Sacramento, CA
the problme ive always been told is that if you watch egts they drop pretty fast once the truck is stopped and they have nothing to do with oil temp or turbine housing/bearing cage temp. i have always thought that you let the engine run so cooling oil (oil is more for cooling than lubrication) can flow through the turbo bearings to prevent coking or boiling of the oil in the turbo which would greatly affect turbo oil flow and life.
 

dmaxfireman

'Can do' kind of guy
Apr 8, 2007
2,329
1
38
CT
yes, like i said.. it has to due with heat soak and static and dynamic temps. if cool air is flowing through the motor and turbo it is taking the heat out and the same goes for the coolant and the oil flowing through it. if you shut off the truck the temps of the metal are much higher and will transfer all the heat to the air and cooling liquids without letting them circulate.

imagine placing your hand in a flame you can leave it there for a second and then switch hands back and forth without burning yourself. but if you leave one hand in the flame (shutting off the truck) you will get burned.

thats the best i know how to explain it... :eek:
 

jc1843

New member
Sep 27, 2009
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86
So Calf
It is not as much of a problem with these turbos, as they are water cooled, but the ones that are not, hold the heat much longer and can cook the oil is shut down when really hot.

I usually wait until the EGT is around 300.
 

fast03

Active member
Jun 15, 2008
1,201
6
38
60
Rancho Cucamonga
upon review, I watched my gauge for the past day and I do shut down around 350-400, but definitely let it idle after a long hard pull.
 

05' Ditry Duramax

New member
May 3, 2008
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Port Orchard Washington
I let it idle down to 300-400 before I shut it down. I also let it idle for alittle longer if I was beating on it.

If i'm on a trip and stop for fuel or to stretch, i'll leave it running. I have a remote starter that alows me to keep the engine running and remove the key from the ignition. Comes in really handy, didn't know I would use it as much as I do.
 

mmangels22

Monty Python Rules.
Feb 12, 2009
801
0
0
San Jose, CA
I thought with modern engines you don't need to let it idle? I mean is there a comparison between a person who has never done this vs someone who has and comparing how much longer the turbo lasts? My question is then how much longer will my turbo last doing the procedure you all are talking about because I don't ever remember reading in my owners manual about turbo cooling off periods.
 

BlkMax

Member
Sep 1, 2008
743
4
18
Wasilla, AK
I thought with modern engines you don't need to let it idle? I mean is there a comparison between a person who has never done this vs someone who has and comparing how much longer the turbo lasts? My question is then how much longer will my turbo last doing the procedure you all are talking about because I don't ever remember reading in my owners manual about turbo cooling off periods.

I never bothered with it until I installed my first chip/EGT. With the Banks installed, I would let it idle until the EGT dropped below 300*, I prefer 275*. Don't ask me why I picked that, I just ended up doing it that way. That was the last 30k miles of 140k miles. Before that, I just never paid any attention.

At 140k, the HTT went in, and I am watching that closely because it is not water cooled like the IHI.

When I took a quick look at the IHI after it came out, there was a LOT of end play in the turbine shaft (never measured, but sure feels like it is moving back and forth axially more than it should). The truck was bone stock to about 110k miles, then the Banks 6-Gun went on, then 22k miles later EFILive went in with a mod II CP3. I have been thrashing the turbo for the last 30k.

I do not know if this helps, but I ended up doing both, ignoring the issue, then really watching my EGT prior to shutting down. The lowest my EGT ever gets is about 250*, and that is at about 0*F ambient. In the summer, I am lucky to get it below about 290*F with 65*-70* ambient.
 

mmangels22

Monty Python Rules.
Feb 12, 2009
801
0
0
San Jose, CA
I see that mostly doing this procedure is more beneficial if you beat on the truck. I have a couple perf mods (tuner and intake) I never go to the track. My truck pretty much only goes on trails for hunting, tows toys (ATVs) and is my DD. I would think that in this instance that I would not need to monitor the turbo so closely. I just question the overkill of this whole thing I mean its your truck do with it what you want but in the end does this really make that much of a difference.
 

05' Ditry Duramax

New member
May 3, 2008
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Port Orchard Washington
I'm sure most of us don't want to ever see the effects of NOT letting the EGT's come down before we shut the truck off. I know i'm kinda speaking "in general". I don't want to replace a turbo if there are things I could have done to possibly "save" it. Knowing or not, I think it's a really good idea. If your stock or heavily modified I would guess it's benaficial but have never tested this or seen anything directly related to not letting the EGT's come down before you shut the truck off.
 

WolfLMM

Making Chips
Nov 21, 2006
4,005
25
48
38
AL
Look at heavy equipment, Cat, Komatsu, John Deere, etc all say let them idle for 10 mins before you shut down for the day. Now a piece of equipment working for 10 hours is a lot different than our truck running to the store. I don't see what it could hurt if you idle a little before shutdown.
 

NemesisDP

New member
Apr 20, 2008
520
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Bloomfield New Mexico
I let the trucks run for about a minute then shut them down unless I have been on a long haul or raceing. The wife shuts her truck off as soon as she gets out and no play in the turbo at 80k wit a hot+2et on 6 all the time. My 06 has more play and I have always let it get down to 350 before shutting it off (62k). I read somtime back that the new trucks should not idle as much as the older ones. (LB7 and newer). I will see if I can find it and post it.