Engine/Transmission (1998.5 - 2002) Turbo cool down: what temperature?

[KGMau]

So... . Now I have injectors and gauges, and I can see the EGT's (they get pretty high compared to my girlfriend's 92' Ford D w/ an ATS turbo). As I recall, the manual suggests a cool down period after a drive up a long, hard grade.



What temperature should the EGT's (pre-turbo) be at before shut-down? The Geno's "turbo-life saver" won't fit on my manual 01' (that I know of), so I'm gonna have to do this manually.





For all of you "manual cool-down" guys out there, at what temperature do you shut down?



(presently I've been using 300 F as the mark).

 

[SnoKing]

You got it 300 degrees. SNOKING

 

[DonBaggett]

I think 300F is the ideal mark, though I sometimes shut mine down around 350 if I haven't run it too hard. I'm thinking about getting the "life saver. "

 

[ChillyDog]

I have been told that anything under 300 is safe to shut down. Thats what I do and I have had zero problems.

 

[Riflesmith]

If we are talking pre-turbo temperature readings, I think you have to consider what the turbo has been doing prior to shutdown. If you just pulled a steep grade with a trailer in tow, when your pre-turbo reading reaches 300 degrees, the post turbo temperature would actually be higher than 300 for a time as the turbine cools down. This fact is the reason for the suggested idle times in the chart in the owners manual.

 

[fj40charles]

300 degrees pre turbo is just fine. If I've been driving it real hard or towing and/or just get off the highway, I'll usually let it cool down longer even though it reaches 300 degrees pre turbo.



Charles

 

[Michael Hughes]

I have both pre and post turbo probes. I would say that if you are talking pre-turbo, I would let it cool down to under 300 before shutdown. I think you really need a post-turbo probe to know when to shutdown. I am using a Westach gauge, two probes and a switch to get both readings.

 

[illflem]

Some gauges aren't accurate in the lower part of their range, you could idle all day and not get to 300. Take your truck for a short drive, let it idle for one minute and see what the temp reads, that should be your safe shutdown temp. To speed cool down remember to turn off the A/C.

 

[TomGolden]

I'm a little more paranoid, so I let mine idle until my SPA pre-turbo gauge reads 275*. And now that I know the newer Series 2 SPA thermocouples are known to read a little incorrectly, I feel better about letting it go under 300*F before I shut the engine off.



Tom

 

[SnoKing]

fj40charles

I carry two keys to the truck with one of those push to unlock the two halves key rings. That way you can lock the door with the engine running and go to restroom. Watch out for keyless entry. Saw a young lady at Safeway once the left her Ford PSD running and the keyless entry will not reopen the door when the truck is running. I think I remember someone saying the Dodge is the same. SNOKING

 

[WestTN]

waht temp?

When idling, the post turbo temp will be the same or LESS than the pre turbo side. After all, it's the engine that creates the heat! While working, the turbo removes heat from the exhaust stream in the form of work compressing the intake air. The bottom line is; 300 degrees is a safe bet no matter which side you monitor.

 

[Steve St.Laurent]

That's not always the case WestTN. I have an Isspro turbo temp monitor hooked to a post turbo thermocouple and my egt gauge runs off of a pre-turbo thermocouple. Here's one example. Say I'm running hard (pulling a big load up a steep grade) and then pull off into a rest area. I decellerate all the way from freeway speed to a stop and never get back on the throttle. My pre-turbo temp will get down to 300 degrees within a minute or so, but it will take 4-5 minutes for the post turbo temp to get down to 300 degrees. In my experience the majority of the time at shutdown post-turbo temps will be hotter than pre-turbo temps (exactly the opposite when running of course). Kmau - you might want to take a look at the Isspro TTM, here's a link with installation instructions that I wrote up - http://www.dieselpage.com/art1199tm.htm . It does an automatic shutdown based on temperature instead of time. I ever have to sit in my truck to wait for the turbo to cool down, I just set the parking brake, take the keys out, lock the doors and start walking away. It shuts down when it needs to. An FYI though - some people have had a relay stick occasionally and the truck stay running. It's never happened to me but I don't walk completely away until it's turned off. I can hear the truck running for a good 300 feet and if it hasn't shut down yet then I'll just stop there and wait a sec to make sure it shuts down.

 

[dresslered]

Steve is 100% correct. Under load, the engine is a heat source and the turbo is a heat sink. After a hard pull, the turbo can then act as a heat source for quite a bit of time after the heat soak.

 

[illflem]

Have any of you with a post turbo gauge seen it go back up after shutdown? Seems like after the airflow stops that the hot steel would raditate heat back.

 

[Cooker]

I have had both pre/post turbo probes for quite some time now and I agree with Steve 100%. At shutdown, 300 degrees pre turbo does not always mean, and more often that not, it does not mean 300, or ever 350 degrees post turbo. Safe shutdown is 300 degrees post turbo, but waiting for 300 pre is certainly better than nothing.

 

[DocStressor]

My probe is post-turbo and I have seen the temperature rise about 25 degrees after shut down. That shouldn't be a big deal.

 

[dresslered]

I see about the same thing as Lee. There is only a slight temperature increase as the post turbo probes are kind of downstream from the turbo. I would imagine that the oil line going to the bearings might probably increase in temperture considerably.

 

[o_mccarroll]

I've seen my pre-turbo EGT rise after shut down by 25* or so. . .