Cool down time

[powerstroke 825]

What should my egts be down to before i shut off my truck? I have been letting it go down to 300 but it takes quit abit of time and i saw somewhere that you should just wait til 350 but im there by the time i put it in park pretty well.
Thanks for the help in advance!!

[POWERED SPARKLESS]

If you get in the 350* your good, with the 6.0's with the VGT will cool much quicker where the 7.3 and non VGT takes longer even if you have a high idle mod. If its something on your mind you could always hook up a turbo timer, you can program them to shut off the truck and different times starting at 10sec on up.

Another thing is to keep in mind how hard you drove the tuck just before shutting down. If driven hard it will take longer, as to where I had a nice neighborhood that I would cruse before getting home and I would usually be in the 350* or lower zone.

[smokersteve]

Yea 350 is good

[colo_dually]

Around 350* is preferred, but the acceptable range is 350-400*

[bfrank81]

I always try to get to 350 it normally takes 1-3 min. I always drive easy either into my drive way or pulling up to a parking spot and I think that cools it down faster.

[smokersteve]

Originally Posted by bfrank81

I always try to get to 350 it normally takes 1-3 min. I always drive easy either into my drive way or pulling up to a parking spot and I think that cools it down faster.

1-3 min? that seems long. what modifications do you have?

[bfrank81]

Originally Posted by smokersteve

1-3 min? that seems long. what modifications do you have?

Stock other than the 4" MBRP but I drive 25 miles one way to work and it's mostly highway. So she builds heat and holds it. Most of the time it's in the 1 min range.

[bfrank81]

Has anyone else noticed that with the AC running the truck takes for ever to drop the EGTs. As soon as I shut down the AC the temp starts to drop much faster.

[howell_jd]

There is no doubt that with more demand placed upon the engine there will be higher heat output so running the AC certainly increases the heat.

Much like with the difference between coolant temp and oil temp providing an indirect measurement of the oil cooler's efficiency, the exhaust temp provides indirect measurement of the turboshaft temperature - the real reason for cool down. Because there is no direct measurement of the oil temperature at the turboshaft or of the turboshaft itself, you need to provide an ample opportunity for the turboshaft to cool below the flashpoint of your engine oil or you will coke that oil. The temperature will be different for different types of oil, the synthetics having higher flashpoints typically. Note that the concern is NOT for the oil to catch fire (not using autoignition temperature here), but the temperature at which the oil could burn if vaporized; flashpoint. The turboshaft spins at tens of thousands of RPMs at maximum boost and is supported with a nearly frictionless floating bearing lubricated and cooled by the thinnest of oil films. It is quite possible for the turboshaft to have a point temperature of nearly the exhaust temperature. If the oil is dirty it will oxidize and coke earlier but once the engine is shut off, there is no pump to continuously circulate the oil over the turboshaft (even when it is not spinning under load) and cool the turboshaft.

What is THE definitive shut down temperature? Under the flashpoint of YOUR engine oil. You will find this on a used oil analysis (UOA) report.

Blackstone Labs
Predictive Maintenance Services, Inc.
Oil Analyzers, Inc. - Oil Analysis, Oil Testing Services

Lower exhaust temperatures provide better shut down considerations for the turbo BUT nothing is universal...after all, extended idling also has negative effects upon piston ring wear. Get the UOA from one of the laboratories listed above or from a truck service center locally where you may get while-you-wait analysis.

Clean oil! Clean filters - and only OEM!

Jonathan

[98SurplusExpy]

I shut down at 400*