idle down to cool turbo

Nope, it says right in your engines manual if any of you bother to read it. A 3 minute cool down is recommended. This allows alot of the heat to dissepate. Not just the turbo, the cylinders also.

I always park, idle, catch my logs up and then I shut down.

 

How about "an old wives tale"
Not to be confused with "an old wives tail"
I always got skraight A's in speeling!

 

It Should take about 3 minutes at idle, just to park...........

 

According the Detroit Diesel's web site for the DD15, he typical warm up or cool down period is not needed.
So I guess if you have a DD15, you don't need to.

 

On a detroit it don't matter because their turbos are crap to start with.

 

This comes from Banks Power

MYTH #7

You have to let a turbo-diesel idle for two minutes before you shut it off.

FACT

This is a current myth that has a basis of fact stemming from many years ago. It also has a kernel of truth regarding today's turbocharged gasoline engines that operate at higher peak exhaust temperatures than turbo-diesels. In the early days of turbochargers, the turbo shaft was supported by a babbitt bearing that could seize, or even melt, if the engine was shut off immediately after sustained boost conditions where the turbocharger would "heat soak". A two minute cool down at idle allowed the turbocharger to dissipate any remaining spinning inertia, and the oil circulation cooled the bearing and prevented oil "coking" in the bearing area. Turbochargers haven't used babbitt bearings for over 30 years, and today's oils resist coking. Synthetic oils won't coke, period. With a turbocharged gas engine, it's still good insurance to let the engine idle for 30 seconds to a minute to allow the turbo or turbos to dissipate any inertia and to cool the bearing area to prevent oil coking, especially if the engine has been worked hard just prior to shut-down. Of course, using quality synthetic oil eliminates this potential coking problem.
Today's turbo-diesels are a different story. There is really no reason to "cool down" a turbo-diesel these days, but you won't hurt anything by doing it either. You can still find people who swear you have to do it, but the myth is fading. Maybe they just like to sit and listen to the radio.

 

Put an ounce or two of today's motor oil in an old frying pan and turn on the burner. Use a lid and stick a temp. probe in there. Try 400° for 5 mins. and tell us if it burned to the pan and went up in smoke.

My Schwitzer bearings looked kind of like some kind of bronze alloy.

 

Another old wife tail.

 

Is that similar to a ex-wife tail?

 

300* is my other rule of thumb but my pyro has been out of commision the past year so I don't go by that. You're right it does take a long time in the summer to drop down to 300* sometimes more than 5 minutes that's why I'll let it idle for longer. Oil temp is a good indication if you know what your exhaust temps were doing, which I do because I've had this truck almost 3 years and I know exactly what every gauge is and should be doing at any given condition. And since my pyro never went over 825* when it was working I'm not real worried about not having one. I'll know if something is wrong even without it. I have other gauges and I know my truck. I don't care what a Banks "study" says (that was from another pposter not you) they are in the business of selling overpriced, overhyped, underperforming performance products for diesel pickup trucks, including turbos.