Idling down to prevent turbos coking: poll

Do you idle down before engine shutdown?

  • Yes

    Votes: 6 14.3%
  • Only when towing or otherwise running considerable boost before

    Votes: 18 42.9%
  • Never

    Votes: 18 42.9%

  • Total voters
    42

freewayman

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Alberta, Canada
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2023 3.5 EB F150 Tremor 401a
What's everyone's thoughts on this matter? Do yall idle down before shutting your engine off?

From my understanding, the turbos on the 3.5 EB are water cooled with passive thermal siphoning. However, is this enough to keep oil from coking?

I've got the habit of letting my engine run idle for at least 20-30 seconds before shutting it down. It doesn't inconvenience me, so I do it for piece of mind. Maybe I'm just being way too old school about this.
 
If I am running it hard I will coast through the neighborhood prior to parking the truck giving the turbos a chance to cool. I am not so sure this is needed much, it's not the 90s anymore.
 
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i don't tow so that's not in my equation but no i do not. my drive home is 25 mph or less the last mile so not worried. on cold startup though i do let the engine idle drop to the 900 rpm from the 1.2-1.3 it starts at even if its for my own piece of mind.
 
Since back in my younger days running diesel tractors the farm, I was taught always to idle a diesel engine for a time to let the turbos cool down.
I don't think about it too much with the EcoBoost.
But then again, I don't tow with mine either.
If I did, I would probably consider it.
 
Im pretty sure this isnt a thing. Our turbos are water cooled, so heat shoudnt be much of an issue. On old diesels maybe, not on these turbos.
 
Im pretty sure this isnt a thing. Our turbos are water cooled, so heat shoudnt be much of an issue. On old diesels maybe, not on these turbos.
When you shut the motor off, does the water and oil keep circulating?
 
For the most part, no, you might get some slight convection. But, because they are cooled continuously, they will not generate the heat the same as a non cooled turbo in the first place that would cause the coking.

My brother is driving a 300k mile gen 1 ecoboost on stock turbos. That truck has been worked hard and put away wet and was never idled to cool down. Ford designed these to be used in such a way. IT would have been cheaper/easier to not add the cooling to the turbos, but they did for this reason.
 
For the most part, no, you might get some slight convection. But, because they are cooled continuously, they will not generate the heat the same as a non cooled turbo in the first place that would cause the coking.

My brother is driving a 300k mile gen 1 ecoboost on stock turbos. That truck has been worked hard and put away wet and was never idled to cool down. Ford designed these to be used in such a way. IT would have been cheaper/easier to not add the cooling to the turbos, but they did for this reason.
That's awesome to hear a high mileage EB still on stock turbos.
 
He had to do the timing set at 280k. The ford techs that did it said you wouldnt have known the engine had that many miles on it by looking at it.
 
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He had to do the timing set at 280k. The ford techs that did it said you wouldnt have known the engine had that many miles on it by looking at it.
Just out of curiosity, what were the oil change intervals and what oil did he run? How much idling?

Want to understand your brothers secrets so my brand new 3.5 will last just as long haha
 
It was my dads truck for the first 220k, then little bro bought it. Its always had 5k oil changes done at the dealership while dad had it. Im not sure about my little brother.

It never really idled at all. Dad always just drove it and parked it. Its mostly all highway miles on it. I think front brake pads lasted to 180k, and rears lasted to 210k or something like that. I dont think they have ever put any other drive train parts in it, or suspension parts. The truck is getting pretty damn rusty though unfortunately, and the several of the blend doors dont work.
 
It was my dads truck for the first 220k, then little bro bought it. Its always had 5k oil changes done at the dealership while dad had it. Im not sure about my little brother.

It never really idled at all. Dad always just drove it and parked it. Its mostly all highway miles on it. I think front brake pads lasted to 180k, and rears lasted to 210k or something like that. I dont think they have ever put any other drive train parts in it, or suspension parts. The truck is getting pretty damn rusty though unfortunately, and the several of the blend doors dont work.

I'm guessing they used the Motorcraft Syn-Blend then unless your dad paid extra at the dealership. I've placed my bets on that oil as well and change it every 4000 miles. It's good stuff.

Was it a pre-alumibody truck?
 
yea its a 2011, dad bought it new.
 
For the most part, no, you might get some slight convection

Thermal siphoning does cause enough coolant flow that I think you could say it still flows after shutoff. It was enough of a feature for Ford to call out in their initial introduction of the EcoBoost as well.

The new EcoBoost V-6 uses two Honeywell GT15 water-cooled turbos.

“The EcoBoost engine uses passive thermal siphoning for water cooling,” Plagens explains. “During normal engine operation, the engine’s water pump cycles coolant through the center bearing. After engine shutdown renders the water pump inactive, the coolant flow reverses. Coolant heats up and flows away from the turbocharger water jacket, pulling fresh, cool coolant in behind. This highly effective coolant process is completely silent to the driver, continuing to protect the turbocharger.”

Going for a Spin - Flat Out
To validate their water-cooled turbo design choice, Ford engineers put EcoBoost through a special turbocharger test.

The test ran EcoBoost at maximum boost flat out for a 10-minute period. Then the engine and all cooling were abruptly shut down and the turbo was left to “bake” after this high-speed operation. If that sounds severe, imagine repeating this cycle 1,500 times without an oil change. That’s what EcoBoost’s turbos endured.

After 1,500 cycles, the turbos were cut open for detailed technical examination. The turbos passed the severe test with flying colors.

“We’ve attained things here the customer would never be able to do in their vehicle,” Plagens said. “Ten minutes of peak power (355 hp, 350 foot-pounds of torque) is something that’s probably only achievable in a vehicle for fractions of a minute, 10 seconds maybe in the extreme. We run it for 10 minutes many, many times over, and that’s far, far more harsh and severe than a vehicle test would be.”
 
never idled down on 3 ecoboosts, and never had an issue. Work fleet has had literally hundreds of ecoboosts go past 100k miles before we sell them off and only lost a handful of turbos, and we don’t tell our employees to idle for a cool down. We also follow the manual recommended oil change interval of 10k miles.
 
40k miles, 35k-ish with a tune, have never done this or thought to. So far so good. (y)

Dont believe this is required anymore on newer vehicles - there's always a chance for mechanical parts to fail, but doing this wouldn't lessen those chances in newer turbo vehicles in my opinion.

Regular maintenance over the long term is the best deterrent for larger problems.
 
I ALWAYS allow the idle down after towing our camper to or from our camp spot, probably not needed, but it probably doesn't hurt!! On the other side, I NEVER idle down after normal driving without a trailer....
 

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