EGT cool down proceedure?

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I know that before shutting of the engine you should let the EGT drop to 300 degrees, however, does this apply to every situation? For example when you pull into a gas station. Should you sit at the pump for 1+ minuets before shutting off the engine? Since you’ll be starting it in a few moments, is it safe to shut down before 300 degrees? Or when you pull up to a drive thru window. It’s hard enough to hear the clerk anyway, so I always like to shut off the engine while I order. Is this safe since you’ll restart right away?

Thanks

Ron

 

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Don't know if it is OK to shutdown and start up right away. If it was only a few seconds duration I would think it would be alright, but at a gas station you will be there several minutes. A drive thru ordering would probably take 15 seconds and may be all right, but I don't know. I always fill up at a gas station two blocks from my home when I first start out, so I don't have to let it idle more than 30 seconds. Here in Hawaii don't have the problem of having to fill on the road after a long drive, unless you run near empty and create your own emergency. At fast food places I always park in the lot and let it idle down and go in to order. A neighbor of mine four houses up the street has a PSD about 3 years old and he always shuts down immediately after arriving home. Doesn't even wait 5 seconds. His truck is still running fine, are PSD turbos not required to idle down?? Do any previous owners of PSDs out there remember what the owner's manual said?

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1996 3500 Clubcab SLT, auto, 4. 10 limited-slip, TST #5, K&N, Dunrite converter, Trans-Go shift kit, Straight pipe, DiPricol EGT, boost & trans temp. gauges, 9 ft. aluminum flatbed and tool boxes with Venco dump. Custom front bumper, Hadley air horn.

 

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Check out this thread for some good info,
Andy http://216. 179. 152. 11/ubb//Forum17/HTML/000131.html

 

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Thanks Andy.

 

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Running around town, picking up burgers, doing errands,fueling and such I never give the turbo temperature or egts a thought. I just shut it off just like I would a gasser.

When pulling off the Highway, pulling a big trailer up a hill, I rarely let it idle over a minute to get the temps down to 300/350. I've shut it off lots of times at 350... .....
47,000 miles and it's still working.

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'99 Quad long bed, 4x4, 5 speed, 3. 55 limslip, DD stage IIs/boost module and elbow, US Gear D-brake, 4" exhaust, gauges, stock filter, air bags and a bunch of other stuff

 

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I was told ,after having my ISSPRO egt gauge installed, as soon as the egt dropped below 400 degs its OK to shut down. By the time the garage door opens my gauge is approaching 300 degs. The only time I let it idle is when pulling my 5th wheel. Then the idle time is usually around 30-40 sec. I was also told that there is no need to let it idle to warm up. The engine warms up faster under load, just keep the boost under 10 psi until the engine temp gauge reads into the normal range. I'm new to diesels so if this is wrong let me know. 2001 2500QD auto 2X4 lwb SLT+ Rhino lined every option Dodge offered except the sliding rear window I tow a 8000 lb 26ft. 5th wheel

 

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Okay here is a question. Do you think that as soon as the gauge goes to 300 (or what ever temp) that that is the actual temp of the turbo parts we are trying to cool. I don't, and here is why. The thermal mass of that little probe is very small, it will cool much faster than the rest of the parts. So I guess what I am saying is this, if you are going to cool down your truck, then once it the gauge reads XXX (what ever temp you decide) you should still wait a while. Remember, this is my opnion and I could be wrong.

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01 2500 SLT+ QC LWB 4x4 Auto 3. 54 rear end Forrest Green Sport with all options avail
DC Nerf Bars, DC Grill Gard, DC mud flaps, Line-X bed liner and Leer 160XL Topper
Power Edge on work bench awaiting install. Gauges and 4" Exhaust in planning stages. Dreaming of transmission
up grades and injectors... ... and some type of Airbox mods.
See My Truck
2000 Skidoo Summit 700

 

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I don't think we have a rocket science situation here. The temp for actual damage is probably a bit higher than 300 so if the gage says 300 it's ok to shut down. I have 142K+ miles on my truck so I must be doing something right. For example, when I pull off of I5 in Williams, CA by the time I have decellerated from 75 (exhaust brake) to the stop sign at the end of the off ramp, gone 100 yds down the street and pulled into the burger joint it's at 300. I just idle long enuff for the turbo to spool down and then shut it off. Pulling up Donner Summit grade with my 32' travel trailer and stopping at the rest stop at the top requires a few minutes of idle to get down to 300.

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Joe George
Eureka, CA

'95 2500 CC auto 4X4,Combo EGT/boost guage,custom switch panel,PacBrake,TST #5,BD valve body,Automatic motorhome steps on both sides,Foldacover hard bed cover,Cummins chrome kit,Black steel grill guard,Front hitch receiver

 

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Keep in mind if you're monitoring PRE-turbo you had better below 300 degrees. I am only currently monitoring POST-turbo which seems to take longer to cool down to 300 degrees due to the amount of stored heat in the turbo. If you are running a high quality synthetic you already have an extra layer of protection against oil coking in the turbo bearings if shutdown temps. are too high. It's kind of a pay me now or pay me later kind of thing with turbo longevity and how that relates to how religious you are at properly cooling down the turbo prior to shut down.

 

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I guess the question here now becomes;

What is considered "coking" temperatures? 300 degrees is really not that hot, and hardly likely to coke bearings, IMHO.

It's really the bearings in the turbo that we are concerned with here, so it would be interesting to know at what temperatures static oil will start coking.

300 degrees really seems low to me for coking to happen.

My . 02

Shawn

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'99 2500 ISB QC 4x4 5spd SB, Camper Special, Tow package, Intense Blue, 275 Injectors, Armourthane color matched box liner, Reese 14K slider, Tekonsha Voyager.

 

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I think you're right Shawn. I would be surprised if the coke temp for a modern CH4 (I use Valvoline Premium Blue) diesel oil is less than 400. However, I still let the EGT (post turbo) come down to 300 before shut down. It doesn't take long unless you have been hauling weight up a hill smoking like a smudge pot.

 

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not to make light of a 300* shut-down goal, but my therapist, during the familiarization ride with my better-than-new truck, informed me of something that might make sense... like anything else, there's a range where the thermocouple is very efficient at making that small current, and correspondingly where the tiny little ammeter (that's what your guage really is) reads that tiny current the best... that range is between 700 and 1200... . your low-temp reads might actually be off by +/- 50* and be still a "good" guage, for quality control purposes... your midrange and high (stay away!!) reads are more likely to be "dead-on"... mine (an ISSPRO) is actually intended for attachment to a post-turbo t-couple, and color-coded "green" up to 900*,yellow to about 1100, and red thereafter... . if that particular guage was connected pre-turbo, it'd be panic city all the time... a 400 reading is supposed to be "OK", though I still do the 300-350 wait, anyway---that'll be worth some points on TDRivial Pursuit, anyway

 

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I have my probe pre-turbo. I waitd to about 275 to shut down, it than climbed to almost 350 with the engine off.

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Paul A. Schmidt
95, 4X4, SLT 2500, 5 spd. , 4. 10, 270 hp. ,675ft. lb. TST, AFC spring kit,215hp. injectors, Pacbrake, Walker muffler,
GearVendor O. D.
Eastern PA.

 

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Here is a copy of a post I made earlier with my take on EGT's for shutdown and also why you will see things like Paul talked about (shut down at 275 pre-turbo and then it climbing to 350 - I don't see this happen with my shutdown based on post-turbo and my gauge being pre-turbo):

I've found that there is a huge difference between pre and post-turbo temps at shutdown. I have an egt gauge hooked up to a pyro pre-turbo and added a pyro post-turbo that is hooked up to an ISSpro turbo-temp monitor. What it does is it monitors the pyro which is mounted post turbo and if it's above 300 degrees (this point is settable) it outputs 12v and backfeeds the ignition to keep the engine running even if the key is removed. So I can pull into the gas station (or whatever) and set the brake, put the truck in neutral, turn off the ignition, remove the key, lock the doors and walk away, the truck idles until it's below 300 degrees.
Now what shocked me was that when I first hooked it up I had my gauge attached to the post turbo pyro as well (to set the temp). I was amazed how often I was shutting my truck off WAY before the turbo was cooled off going by my pre-turbo gauge. I like having the gauge pre-turbo for performance reasons but for shutdown the post-turbo is a must, IMO. What I found is that some of the stuff people say to cool the turbo like decelerating in gear as long as possible (which I did), that look like they are cooling the turbo faster actually arent. There are many times that my pre-turbo egt gauge will read below 300 for 3-4 minutes before the engine shuts off (hence below 300 after turbo).

I think I have the best of both world's, pre-turbo pyro with a gauge to watch for high egt's in the best place, and a computer making sure my engine doesn't shut down until after turbo get's below 300 (I have an emergency kill switch right behind the ignition key too). See my post https://www.turbodieselregister.com/ubb//Forum3/HTML/000507.html regarding the installation of the turbo temp monitor. Total cost for it was $180 and it's the most convenient thing I have on my truck.


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-Steve St. Laurent - President of the Great Lakes TDR, Chapter Forums Moderator
'98 Quad Cab Long Bed (CMNSPWR), 4x4, ISB, 5sp, 4. 10 LSD, Prime-loc remote fuel filter, boost & pyro gauges, TST Powermax, muffler eliminator, 5" chrome tip, BD Exhaust Brake, Isspro turbo temp monitor, Permatech spray in liner, Grizzly stainless nerf bars, Stull SS grill & bumper inserts, Front Draw-Tite receiver, BFG 285/75R16 AT KO's

 

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Yes, Ford does recommend a cool off: "To prolong engine life(after extended high speed or maximum GVW operation)it is recommended that a hot engine be allowed to operate at a low idle for about 7-10 minutes which would allow sufficient time for the turbocharged engine to cool down. "
That seems like an awful long time, I think they are just covering thier butts since they don't provide a way to tell how hot it is.
Aside from the bearing itself I have seen pictures of the oil passage being choked with oil coke. (Maybe on the Allied-Signal web site?)

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2000 F250 Reg Cab 2wd under-valved and over-cylindered PSD 6spd. (I know, I made a mistake)
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