Turbocharger operation question

[Onceaneagle]

A friend of mine just told me that you should not shut off a turbocharged engine unless you idle for 2 minutes because of potential damage to a bearing. He claimed that once the engine is turned off, no more oil goes to that bearing but the turbo fans continue to spin and the bearing will eventually be damaged. Shouldn't that be engineered out? He heard this warning from our John Deere salesman and yeah that is a turbo tractor. But I'm just asking for someone who knows Ford motor turbochargers better than me if it is something to be concerned about.

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[stuartmunto]

Pretty sure this isn’t a thing in modern turbo engines. It was definitely a thing in the 90s era where turbos were only oil cooled, but modern turbos are water cooled (from my limited knowledge - I could be wrong) as well as oil cooled?

turbo engines are everywhere today - from small hatchbacks, luxury cars to sports cars. The average person isn’t idling their car after driving.

From my limited knowledge I would say with normal day to day driving no idle is needed.

However, after a hard driving session or track session then an extended idle before shutdown would be a good idea - not only for the turbos but for all engine/drivetrain components, but usually a cool down lap is done so an extended idle probably also is not needed either

the John Deere dude might be correct for tractors as I can’t imagine tractor engines being in the bleeding edge of modern turbo tech

edit: I would say a good quality fully synthetic engine oil, which is routinely changed every 5,000 miles is better for your turbos than worrying about idling

 

[BigOleOgre]

A friend of mine just told me that you should not shut off a turbocharged engine unless you idle for 2 minutes because of potential damage to a bearing. He claimed that once the engine is turned off, no more oil goes to that bearing but the turbo fans continue to spin and the bearing will eventually be damaged. Shouldn't that be engineered out? He heard this warning from our John Deere salesman and yeah that is a turbo tractor. But I'm just asking for someone who knows Ford motor turbochargers better than me if it is something to be concerned about.

Pretty sure this isn’t a thing in modern turbo engines. It was definitely a thing in the 90s era where turbos were only oil cooled, but modern turbos are water cooled (from my limited knowledge - I could be wrong) as well as oil cooled?

turbo engines are everywhere today - from small hatchbacks, luxury cars to sports cars. The average person isn’t idling their car after driving.

From my limited knowledge I would say with normal day to day driving no idle is needed.

However, after a hard driving session or track session then an extended idle before shutdown would be a good idea - not only for the turbos but for all engine/drivetrain components, but usually a cool down lap is done so an extended idle probably also is not needed either

the John Deere dude might be correct for tractors as I can’t imagine tractor engines being in the bleeding edge of modern turbo tech

edit: I would say a good quality fully synthetic engine oil, which is routinely changed every 5,000 miles is better for your turbos than worrying about idling

Exactly what Stuart said. There is no risk of damage from shutting down after driving, unless it was directly after hard engine work where the turbos get real hot. -Full boost run, Racing, or towing. It would be a bad idea to do a 1/4 mile drag or hot lap on the dirt track, then immediately pull over and shutdown, but other than that there is no worry for modern turbo'd automotive engines. I cannot speak on the tractors.

 

[Onceaneagle]

Didn't think it was an issue for most of us. Thanks.

 

[bigb]

It is designed so that after shutdown hot coolant rises away from the turbo bearings thru natural convection and cooler coolant replaces it. I still wouldn't hesitate to give it a minute of idle time if you just finished a hard pull though, that's my plan anyway.

Something to note, if accurate, is the statement "to reduce the potential of oil coking" as opposed to "eliminate".

 

[DutchRanger]

90s thing.

 

[Onceaneagle]

As time marches on technology gets newer and we get older. Appreciate the information.

 

[CoastieN70]

Agree with most (if not all) comments. That being said, I always idle my engine for 30 or so seconds before shut down. I figure a couple extra seconds of cool down can't hurt.

 

[POULINR]

Thanks for clearing the turbo issue up….

 

[ChronciallyChronic]

When you're running using lots of turbo, under continuous acceleration, hard pulling...anything that puts load on the turbo, yes it's a good idea of idle for minute or so to allow for some cooldown. Every day usage, it is 100% not necessary. If it was I would have blown the turbo on my previous car, a 2016 Fiesta ST; that turbo worked a lot and I didn't do cool downs - no problems in 120k miles.

Now oil changes, those are mighty important with a turbo.

 

[Greys]

I always give a turbo engine a minute or two to warm up - even in the summer, and a minute or two to cool down before shutting off, I am not too worried about the cost of the gas. All the manufacturers say they have eliminated issues with technology, but then they also say things like the oil in some components is good for a lifetime... In my opinion, things are designed to last until warranty, and then all bets are off. I am still convinced that over the long term, 10-15 years, a proper warmup and cooldown cycle will extend the life of exhaust components and metals. Also, it lets the manifold metals shrink a little bit slower going from high exhaust gas temp under load, to exhaust gas temp at idle, to off and cold, instead of going directly from hot to off and cold. Most people will definitely not feel the same way.

 

[kevinmxz700]

If you have been working turbo hard, yes give it a minute before shutting down

QUOTE="Onceaneagle, post: 345051, member: 13395"]
A friend of mine just told me that you should not shut off a turbocharged engine unless you idle for 2 minutes because of potential damage to a bearing. He claimed that once the engine is turned off, no more oil goes to that bearing but the turbo fans continue to spin and the bearing will eventually be damaged. Shouldn't that be engineered out? He heard this warning from our John Deere salesman and yeah that is a turbo tractor. But I'm just asking for someone who knows Ford motor turbochargers better than me if it is something to be concerned about.
[/QUOTE]

 

[fueler]

I hate the auto start stop as many do, but if enabled shuts down the engine right away no cool down, so there's that!

 

[maolizi]

Your friend isn’t totally wrong, but it’s more nuanced with modern setups: turbochargers ride on very small, high-speed bearings (often oil-fed journal or ceramic ball bearings), and after hard operation the turbo can be extremely hot, so shutting the engine off immediately stops oil flow while the shaft may still be spinning and heat can “cook” the remaining oil in the bearing housing (coking), which over time can damage bearings and seals; that said, most modern Ford turbo engines use improved cooling (better oils, water-cooled center sections, and tighter engineering tolerances) that make them far more tolerant than older turbos, so you don’t need to religiously idle two minutes after gentle driving, but after towing, long highway pulls, or hard acceleration, letting it idle 30–90 seconds is still smart practice to stabilize temperatures and protect the turbo Backing bearings long term.

 

[danmoochie]

It is way more important to start the truck up and let it run until it throttles down than anything else. I do it religiously. That way you have oil everywhere it needs to be and lubricated before you start accelerating. That is something and good mechanic tell you every day. Lot of guys jump in the truck, push the button or turn the key and slam it into drive. That is the worst thing you can do!

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