Turbo Cool Down

[compindustries]

Do any of you let the vehicle / turbo cool down to the recommended 325 degrees before killing the motor?

I have been doing it religiously since I purchased the vehicle in 2003 and was curious if I am crazy and just wasting fuel.

For 2.5 years I just sat in the seat and watched the EGT Gauge, but now with the remote start I am able to get out, remove the keys, and lock the doors, however, if Ford recommends this cool down, why would they not make a turbo timer standard on the PSD?

[Faceplant409]

If I come off the freeway and come to a stop before a little city driving, yes I'll let it Idle a little bit. I do not have gauges as of yet but I can see the point in this practice.

Pat

[pajuis]

I run a turbo timer and use it after trips or hard use.

[sullyx7]

When I'm towing or occasionally driving hard, I let the truck idle for a few minutes to cool down. During normal driving I don't worry about it.

[bcof250]

I have always let my truck cool down after hi speeds or pulling. Those turbo's are way to expensive to replace. I know of severl people with the 7.3's that had to get there turbo's replaced under 100k miles and the is the first thing I ask them about there truck. Most cases they did not let it cool down. My 97 model has 245K on it now, most of it pulling heavy trailer. Always, always let that turbo cool off.

[compindustries]

So then I have to ask, why would Ford not make a turbo timer standard equipment on all PSD's? It would appear that it would be something beneficial.

@ pajius, what timer do you use or do you use a timer built into the programmer like an Edge?

[AllOutFirefighter13]

[ QUOTE ]
If I come off the freeway and come to a stop before a little city driving, yes I'll let it Idle a little bit. I do not have gauges as of yet but I can see the point in this practice.

Pat

[/ QUOTE ]

I do the same thing, but I do agree with you and wonder why Ford wouldn't advise a cool-down period under certain driving conditions (heavy-towing, high-speeds, as was mentioned). It's hard to say. I sure wish that we could ask the engineers of these engines these questions. The technicians that post here are awesome and greatly contribute, but there are even some questions they are unable to answer.

[Dr.Evil]

[ QUOTE ]
and wonder why Ford wouldn't advise a cool-down period under certain driving conditions (heavy-towing, high-speeds, as was mentioned).

[/ QUOTE ]
FMC advises exactly that in the owner's manual.... In fact it's been in the onwer's manual of every vehicle I've ever owned....

[AllOutFirefighter13]

Denny,

I don't have my owner's manual with me, but is it a generic period that covers ALL engines (diesels, gassers, etc.). Also, does it specify the length of time, 'cause now we are being told that it's not good to let these engines idle tooooo long? Just curious!!!

[Black05]

IIRC, there was a prior thread on this that someone with a timer stated that his exhaust temperature cooled down (to either to 300 or 400 degrees -- whatever he stated was the the proper temperature for shut down) in about 30 seconds after a hard towing trip. Accordingly, just allow one extra song to finish on the radio after a long trip towing and your exhaust temperatures should be fine. During normal in-town driving, immediate shut off should be okay.

[Dr.Evil]

That's going to cool Your exhaust gases but what about the rest of Your engine? In a gasoline powered engine at a substantial load, say only pulling 2-3 inches of vacuum the exhaust valves run about orange hot... but because they're a high nickel content alloy they survive. Plus most engines today use induction hardened valve seats to tolerate no-lead gasoline. A turbo-diesel will see almost as high of temps under load.... so Your exh. gas is 300-350 but Your valves, turbo, piston tops, etc. are still VERY hot. What are We actually trying to cool here? [img]/ubbthreads/images/graemlins/shrug.gif[/img]
The Owner's manuals say three to five minutes, and I wait at least that long....but then My commute is almost an hour at 70-80 mph.... My little commuter car is a turbo-gasoline and all aluminum with full synthetic oil so I don't let it cool as much as I let My PSD....

[Black05]

[ QUOTE ]
The Owner's manuals say three to five minutes, and I wait at least that long...

[/ QUOTE ]

The owners manual does discuss cool down time, but only in relation to extending turbo charger life. It mentions nothing about cooling of valves, pistons, internal bearings, etc. Fact of the matter is, there is no way that those internal parts are going to cool appreciably in 3-5 minutes. However, exhaust gases do cool in a short time as the piping containing them is thin and exposed to much cooler atmospheric temperatures so that thermal cooling can take place.

If you look in a gasoline engine owners manual, there is no cool down period mentioned (at least I have never seen this mentioned in the plethora of gasoline trucks I have owned.)

[Dr.Evil]

Why wouldn't pistons, rings, & valves get hot just like the turbo? They're exposed to even hotter combustion gases than the turbo. And I would expect pistons that are running 800-1000 degrees F WILL cool down when exposed to combustion gases running 300-350 deg. Plus You still have the oil jets spraying 180-200 deg. oil on the undersides of the pistons that will cool them, Plus heat transfering into the cylinder walls through the rings...plus the waterpump circulating water thru the heads, block, & oil cooler...
Have You ever noticed what happens to a NEXTEL (Winston Cup) Car during qualifying? The water or coolant that blows out of the radiator overflow when they kill the engine instantly when they're across the finish line on the last lap? Don't You think Your PSD would and WILL do that on a hot day at full load and You shut it off without a cool down? FRANKLY, if it's really hot and Your working Your truck hard like pulling mountains close to max. GCWR I don't think a half hour cool down is too long. It's not like wet stacking is going to be a problem.
I won't comment about what You remember reading in old truck Owner's manuals but I remember what I've read in Mine. [img]/ubbthreads/images/graemlins/grin.gif[/img] I've seen many N/A gasoline engines running with the cast iron exh. manifolds glowing cherry red. That's just about the temperature that takes the temper out of piston rings and causes them to not seal properly... And as far as what Owner's manuals say or not being good operating practices for an engine..... Remember they want to get You through the warranty period is all...

[tzurick]

This is from the Banks website. Whether it's true or not I don't know just thought I'd share. I let mine cool down to under 400 after a heavy pull. I find getting down to 300 to be next to impossible.

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.

[chrislib]

While I don`t own a Ford, I do have a diesel and I always allow it to cool to at least under 400. The little time it takes gives me peace of mind...my .02

Chris