Is letting the engine idle to cool turbo necessary anymore?

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Talking about turbocharged engines, of course. It used to be common knowledge, especially in the trucking industry, that you let the engine idle for about 5 minutes before shut down so oil wouldn't bake and coke up in the turbo bearings. With modern oils, especially the synthetic options we have now, is this still necessary? As I understand it, a lot of newer turbos are liquid cooled as well. I usually let the engine idle for about a minute before shutdown on my 7.3 Powerstroke after a highway run, and about 5 minutes if it's been towing. Am I wasting my time? Or is this still a good thing to keep doing?
 
Of course it is. but synthetics and turbos have both evolved.
Not as reliable as NA, but slightly better than they were b4.
 
Originally Posted By: jongies3
Talking about turbocharged engines, of course. It used to be common knowledge, especially in the trucking industry, that you let the engine idle for about 5 minutes before shut down so oil wouldn't bake and coke up in the turbo bearings. With modern oils, especially the synthetic options we have now, is this still necessary? As I understand it, a lot of newer turbos are liquid cooled as well. I usually let the engine idle for about a minute before shutdown on my 7.3 Powerstroke after a highway run, and about 5 minutes if it's been towing. Am I wasting my time? Or is this still a good thing to keep doing?


It depends if the turbo is lubricated by the engine oil or has its own oil and reservoir. If the latter you can shut off immediately if the former I'd let it idle for at least couple of minutes as if you shut the engine off you also shut off all lubrication to the turbo.
 
If I have ran the Powerstroke or either of the MBs hard (or have been towing) before stopping, I let them idle a bit, should not hurt anything to do so.
 
I would want to believe that newer turbocharged vehicles would have the technology to keep fans on and oil circulating through the turbo during shutdown so the turbo can be cooled to prevent damage.
 
Originally Posted By: Pelican


It depends if the turbo is lubricated by the engine oil or has its own oil and reservoir. If the latter you can shut off immediately if the former I'd let it idle for at least couple of minutes as if you shut the engine off you also shut off all lubrication to the turbo.


Curious as to what Passenger Car or light truck have turbo with its own oil and reservoir?


With my 2019 Cherokee it runs some kind of pump after shutoff.. I hear it but haven't investigated yet.
 
Originally Posted By: rooflessVW
Just don't floor the throttle while you're looking for a parking space and park with the manifold red.


Exactly. Just take it easy the last 5 miles before destination and you should be good
 
My Jetta has an auxiliary water pump and I think I heard the fans running after shutdown the other day. Also some cars have evaporative cooling for the turbo, as well.

Turbo cars made this century? I challenge you to find a oil cooled turbo car made for the NA market this century. Turbo cars made in the last decade? No way!
 
Some cars do have a turbo timer that keeps things circulating while the car is off so that you don't explicitly need to do it yourself. It either keeps the engine running, circulates the oil or the coolant. Similar to how cars have fan timers that keep the cooling fans turning for a bit after the car is shut off.

They also sell aftermarket turbo timers if you don't have one already.

Quote:
Curious as to what Passenger Car or light truck have turbo with its own oil and reservoir?

Yup I'm interested in learning myself. I only know of superchargers that have their own oil supply and their own prescribed oil, which makes sense because they don't get as hot, but most turbos I'm aware of come with oil supply and return lines that work with the main oil supply for the rest of the engine.
 
My MKV GTI will run the aux waterpump for up to 15 minutes after shutdown when needed, and the fan.

This takes care of the hot Turbo after a flogging.
 
Originally Posted By: 123Saab
My MKV GTI will run the aux waterpump for up to 15 minutes after shutdown when needed, and the fan.

This takes care of the hot Turbo after a flogging.


My wifes Audi and my VW use an electric auxiliary water pump. I blame the electric water pump for my battery being short lived in my car,
but the turbo in GTI's are actually very reliable.
 
I think it is always good to let an engine idle after a long highway run, turbo or non turbo. This lets the exhaust valves and other hot parts normalize before a shutdown. Maybe an old way of thinking but, an extra 30-60 seconds is not much out of a 24 hour day.. Ed
 
Originally Posted By: NoNameJoe
Curious as to what Passenger Car or light truck have turbo with its own oil and reservoir?

The Porsche Mezger engines have turbos with their own oil tanks to prevent starvation in hard cornering. An oil change consists of four plugs. Sump, tank, left turbo, and right turbo.
 
If your drive into the neighborhood is slow, then just shut it off.

If however, you arrive at work in a blaze of turbocharged glory, 100MPH down the perimeter road, to zero in a few seconds, while sliding into your parking spot, then it might be a good idea to let it idle for a bit.

Of course, that idle time gives others a good sized window to find you and chew you out.....relating this for a friend....
 
Originally Posted By: Eddie
I think it is always good to let an engine idle after a long highway run, turbo or non turbo. This lets the exhaust valves and other hot parts normalize before a shutdown. Maybe an old way of thinking but, an extra 30-60 seconds is not much out of a 24 hour day.. Ed


You're worried about the exhaust valves melting caused by highway driving in a naturally aspirated car? That's terrible advice.

If you use your car for a single, one way trip each day then 30-60 seconds is not that much I guess.
 
Originally Posted By: skyactiv
My wifes Audi and my VW use an electric auxiliary water pump.

My Audi had the same deal, along with blowing air across the injector assembly after shut down when hot.
 
Originally Posted By: Cujet
If your drive into the neighborhood is slow, then just shut it off.

If however, you arrive at work in a blaze of turbocharged glory, 100MPH down the perimeter road, to zero in a few seconds, while sliding into your parking spot, then it might be a good idea to let it idle for a bit.

Of course, that idle time gives others a good sized window to find you and chew you out.....relating this for a friend....

Lol, yep I've seen the video of that fat Prius lady chewing out a guy in a diesel pickup for letting it idle, that was amusing! Haha
 
I have a Garrett T3 on my Chrysler 2.2. Been spinning since 1986, engine oiled and water cooled. The most I let it idle is around 20 seconds before shutdown. That's only if I have been on it a bit like on the highway and pulling into a gas station. Normal driving about 5 seconds. Still going but I don't beat on it anymore.
 
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