3.5 turbo let run ?

[XLT22]

On similar sized aircraft engines with similar sized turbos, the issue of coking and scoring of the bearings is a known problem. Unless there is a designed in feature to provide lubrication during shutdown there is a real risk of damage. I'm sure they spin down quickly... but when you start from 100,000 rpm it can still take a measurable amount of time. Appreciate your assurances but they don't ring true.

So you’re pulling the ‘ol “I reject reality and substitute my own” defense.

There is no scenario happening as you describe unless someone sits in the cab flooring the throttle while manually pulling the wastegates shut with a rope while shutting the engine off. Under normal operating conditions compressor speed is always going to be controlled with wastegate position and throttle valve angle.

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[Gros Ventre]

So you’re pulling the ‘ol “I reject reality and substitute my own” defense.

There is no scenario happening as you describe unless someone sits in the cab flooring the throttle while manually pulling the wastegates shut with a rope while shutting the engine off. Under normal operating conditions compressor speed is always going to be controlled with wastegate position and throttle valve angle.

Your opinion is not reality. Unless Ford designed in an after oiler setup, your assertions are just opinion. Have a nice day.

 

[Aonarch]

Hi folks , heard something today and just wanted to ask on here about it. My 2022 3.5 Ecoboost , should I let the engine run for a couple minutes after I park before shutting off because of the turbos? I normally give it a descent enough warm up from cold before driving anywhere and that’s about it . Thanks

No, that is old school mentality back when turbos were still early in their development cycle and were oil cooled.

If you want to be extra careful, after seeing high loads like towing, you can idle for 30 seconds or so before shutting off. But definitely not needed everyday. But typically people are off boost while pulling into a parking spot or driveway, so no idling is required.

Modern cars with electric water pumps run the pumps after shutdown for the turbo/s.

 

[Gros Ventre]

No, that is old school mentality back when turbos were still early in their development cycle and were oil cooled.

If you want to be extra careful, after seeing high loads like towing, you can idle for 30 seconds or so before shutting off. But definitely not needed everyday. But typically people are off boost while pulling into a parking spot or driveway, so no idling is required.

Modern cars with electric water pumps run the pumps after shutdown for the turbo/s.

The issue isn't water, it's lubrication...

 

[Aonarch]

The issue isn't water, it's lubrication...

Plenty of oil in the turbo after shutdown to handle the spin down.

Boundary layer is there.

If this wasn't the case, we'd see frequent turbo replacements as the norm.

Not the case. Usually turbos die from seals and o-rings aging, not from scouring.

 

[Gros Ventre]

Plenty of oil in the turbo after shutdown to handle the spin down.

Boundary layer is there.

If this wasn't the case, we'd see frequent turbo replacements as the norm.

Not the case. Usually turbos die from seals and o-rings aging, not from scouring.

The issue is it is quite rare to go from high power to engine cycling off immediately. If you're parking or otherwise at low power the turbos are not spinning to any significant amount. when you draw conclusions from low power to off versus high power to off, you are talking apples to oranges. Anecdotal experience in the shop does not pass the engineering of the system. Boundary layers are quite thin and need replenishment. Again: I'm speaking to high power to immediately engine off. Low power, city driving, etc to engine off doesn't stress the system and since that is much of what a truck sees, that is why seals and such age out.

 

[Aonarch]

The issue is it is quite rare to go from high power to engine cycling off immediately. If you're parking or otherwise at low power the turbos are not spinning to any significant amount. when you draw conclusions from low power to off versus high power to off, you are talking apples to oranges. Anecdotal experience in the shop does not pass the engineering of the system. Boundary layers are quite thin and need replenishment. Again: I'm speaking to high power to immediately engine off. Low power, city driving, etc to engine off doesn't stress the system and since that is much of what a truck sees, that is why seals and such age out.

And I specifically talked about that in my first comment that you quoted.

 

[XLT22]

Your opinion is not reality. Unless Ford designed in an after oiler setup, your assertions are just opinion. Have a nice day.

Why keep arguing with people that actually assemble and service the vehicles? There are a few of us on here telling you you’re wrong.

 

[v8440]

Because theory and airplanes. And you're ignorant, too.

 

[Chris GTO TT]

I've seen this thread pop up on various forums across multiple manufacturers for the better part of 25 years now. The answer is always the same, on water cooled turbos it's not a problem. Little old Subaru figured it out 30+ years ago. The basics are the water (antifreeze) in the turbo cartridge will boil off, and be replaced by cooler water at temperatures far below the temperature where oil would begin to burn in the cartridge. The turbos are low mounted so there is ALWAYS water water in the cartridge. As for the oil side there's usually plenty of oil in the feed line to protect the bearings for the spin down.

The short version: if a tiny manufacturer like Subaru could figure out how to cool their turbos post shutdown 30+ years ago I can guarantee Ford has too.

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