Usefulness of running radiator fans after shutdown?

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I'm wondering how useful continuing to run the radiator fans after shutdown as some vehicles do actually is at helping prevent heatsoak related problems. I understand that the coolant and oil temperature can rise significantly after shutdown since they stop circulating but keep absorbing heat from the block and head, which can cause undesirable effects like oil breakdown and coolant boiling. I assume that the goal of continuing to run the fans after shutdown is to help reduce the temperature spike after shutdown, but I question how effective this strategy actually is.

It seems that since the potential coolant boiling, oil coking, etc is going to occur inside the engine, blowing air through a radiator with no fluid circulating through it and over the outside of the engine isn't going to do much to help anything. The one exception I can think of is if the vehicle used an electric water pump that also continued running after shutdown, but if the coolant was kept circulating I doubt that running the fans would even be necessary under most conditions since no more heat will be generated after the engine is shut down.

What do you think about continuing to run the fans after shutdown? I'd be interested to hear any thoughts you have on this.
 
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....... It seems that since the potential coolant boiling, oil coking, etc is going to occur inside the engine, blowing air through a radiator with no fluid circulating through it and over the outside of the engine isn't going to do much to help anything.....
This is exactly correct. The cooling process, (fans blowing), has to be done with circulation, (water pump operating), or it's useless. I had a motorcycle that did this. (1985 Kawasaki Voyager inline 6).

If I parked it on a hot day after a long ride, the radiator fan would kick on and off several times. This was hard on the battery, and I had it hooked up to a low amperage charger in order to offset this constant drain.

But it killed several batteries over time. Just a bad design that didn't really accomplish anything. I had other liquid cooled bikes that didn't do this, so I was convinced it was a useless feature.

As for the newer cars, I'm not sure what type of cooling system they employ in regards to what happens after they're shut off. I have parked my 2018 Toyota Camry, (2.5 L 4-cylinder), in the garage after driving it uphill for over 3 miles in 115 F+ temps with the A/C on full, and it has never run any cooling accessories after it was shut down.

In the hot weather I do have large pedestal fans set up to blow air through the grille of all of my vehicles, to offset some of the heat soaking that takes place during the hot Summer weather, that occurs here in the desert during the hotter months.
 
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If it didn't help, cars wouldn't do it.

Heat in the engine bay is what kills plastic parts, seals, and the paint on your hood. Any removal of heat is a good thing.

If my Touareg is running the main fan after shutdown, it is because a regen was interrupted and you absolutely do not want that type of hot air trapped under the hood.
 
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The hot coolant in the engine will overcome the cooler coolant in the radiator (pressure differential) and “puke” the hot coolant in the radiator and cool coolant in the block. FWIW cars in the twenties used this for cooling sans an actual water pump.
 

JTK

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Maybe some higher end or turbo'd vehicles do this now, but I haven't noticed an E-fan equipped vehicle do this in decades. I recall some FWD Chryslers and Fords doing this in the 1980s-90s. K-car and Ford Tempo perhaps?
 
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In

That's why the radiator fan runs?
Usually all the fans run (including the radiator)

Are you in an extraordinarily hot area?
learned a new term
post shutdown overheating

But when I’ve had afterblow enabled all the fans run a while, google says up to 5 minutes
 
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Maybe some higher end or turbo'd vehicles do this now, but I haven't noticed an E-fan equipped vehicle do this in decades. I recall some FWD Chryslers and Fords doing this in the 1980s-90s. K-car and Ford Tempo perhaps?

I had a Dodge Omni that did that.
 
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If heat soaking is that much of a concern, (and it is out here in the desert), the best solution is to open the hood and run a fan for a hour. It's somewhat of a ****, but it's better than running down your battery without much to show for it. Obviously you need a garage for this.
 
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Usually all the fans run (including the radiator)

Are you in an extraordinarily hot area?
learned a new term
post shutdown overheating

But when I’ve had afterblow enabled all the fans run a while, google says up to 5 minutes
As I said earlier in the thread, my Touareg only ever runs the fans if a regen was interrupted.

I have never had the cabin blower run after shutdown in any of my cars unless I had a rest or vent function enabled.

I had a Dodge Omni that did that.
My 280ZXT had a fuel rail blower to help prevent vapor lock.
 
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The hot coolant in the engine will overcome the cooler coolant in the radiator (pressure differential) and “puke” the hot coolant in the radiator and cool coolant in the block. FWIW cars in the twenties used this for cooling sans an actual water pump.
By "puking" you mean convection?
 
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I had a "tank" engine coolant heater that worked on this principal. It would draw cold coolant out of the bottom of the radiator. Heat it with a 1,500 watt heating element, where it would run up a hose into the engine block and warm the engine by convection. (Cold in at the bottom... Hot out at the top).

It worked OK, and the car started on the coldest of mornings. But I doubt I would want to depend on that kind of principal to cool an engine. I rather doubt it would be able to keep up.

That heater had to run for a couple of hours to make the cylinder heads warm to the touch. A bit like trying to warm up a big V-8 engine in the middle of Winter with a jury rigged Mr. Coffee.
 
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Some cars have an electric water pump, and if they don't, a lot of turbocharged engines have a smaller electric circulation pump to continue to move coolant through the turbocharger after shutdown. The fans staying on for a few minutes would help in either case.
 
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As I said earlier in the thread, my Touareg only ever runs the fans if a regen was interrupted.

I have never had the cabin blower run after shutdown in any of my cars unless I had a rest or vent function enabled.


My 280ZXT had a fuel rail blower to help prevent vapor lock.

Likely to stop the “burning smell” complaints when folks interrupted burn off and parked in a garage, may have also been a fire hazard
 
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One of the many egoboost innovations that Ford made note of in their documentation is the use of "thermo-syphon" strategy in the ngines.

The idea is that the engine cooling system is constructed so as to allow flow due to high heat to move the coolant through the system and avoid severe heat soak.

otherwise save your batteries!
 
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A couple things to think about...

Some cars run not only the E-fan but a E-coolant circulation pump. I know my Alfa did that. I believe another car I owned did that as well...maybe the 500 Abarth?

I also believe it was VW that designed the coolant system on their old 2L diesel TDI such that a temperature differential would circulate coolant through the engine/turbo/cooler when the car was off...so the fan was actually useful.
 
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