Streamliner

I imagine this may have been discussed here already and if so, I apologize. The engine cooling fan in my 2022 S580 continues to ROAR—for what seems like five minutes or more—after I turn off the ignition. I thought this had a lot to do with the hot summer weather, but things have really cooled off here recently and the fan continues to do this. Today, I drove the car on city streets about five miles, I bring it back home, put it in the garage and the fan continues to run, at what seems to be a high speed. It is actually quite annoying. My three W222’s I had previously would do this every now and then, but only after long, highway drives on hot, summer days.

Does everyone have the same experience? Thanks.

chassis

Fans roar when they operate. It's a normal sound of a functioning fan.

The question of whether, and for how long, the fan operates is decided by the powertrain electronics.

JSL555

My former 2021 750i did this almost all the time. My current 2022 S580 has only done this a half dozen times in the 6 months - I have put 7000 miles on the car. In each instance when the fan ran on after I shut the engine, I can relate it to my long/hard driving that drive. So, I believe it happens only when the engine is running hot. You might want to check the coolant temperature gauge before you shut it to get a sense of what may be happening.

crabman

You sure it's not an idiot gauge? More common than not nowadays.

JSL555

Semi idiot gauge….the gauge doesn’t show the temperature gradations but you should be able to readily see if its running on the higher side of “normal”, designed to be fairly central in the gauge. I wouldn’t be concerned unless it runs hot with non-aggressive city driving.

Bubba1

In my S580 the fan does run after driving but much more after aggressive drives. Doesn’t bother me…seems pretty normal as other cars I have or owned in the past did some sort of variation of cooling.

crabman

A lot of gauges now simply connect to a switch rather than anything capable of reading a measurement; the gauge just shows pure BS controlled by software. As an example an oil pressure gauge may simply have a switch that kicks at 10 psi and everything you see on the gauge is generated by software that doesn't even have any way of knowing actual pressure. You get the low pressure light when the pressure falls below that 10 psi set point without the car ever having known what the pressure was at any time other than being above or below the switch trigger. This sort of thing is very common and becoming more common every year. Temp gauges often work the same way with a switch that kicks at a set warmup temp and one that triggers at a set overheat temp while what you see on the gauge is completely made up. This is exactly what is in my Panamera which shows the same 194 as every other Panamera when warmed up; everything the guage shows is a fiction brought to us by people who think we are stupid. I would presume any gauge to be fake until you can find proof that it actually has a real world connection to a real world sending unit capable of taking a measurement. Even then I would consider what the gauge is showing to be highly suspect until verified with your own working gauges.

JSL555

That’s a pretty cynical view so I hope you are speaking from personal knowledge of the mechanics. I will tell you that my ‘bogus’ temp gauge does move as the engine warms up. It seems to start at ambient temperature (never at the zero point) then move right as the engine runs…takes just a few minutes to reach “operating” temp.

I would love to hear what others see on their gauges.

Streamliner

You know, I can remember installing a set of Stewart-Warner gauges in my 1956 Oldsmobile. They looked SO cool and as a young guy, it seemed so “important” to know every heartbeat of my 324 cubic inch “Rocket” V8 back then. Today, honestly, I’m one notch above my wife on cars. She says “I just want to get in the car and go.” For the most part, I don’t pay any attention to much of anything to do with the cars, as long as they are doing what they are supposed to do. Get them serviced as required and if they break, take them to the dealer for warranty repairs or call MB Roadside Assistance. I pay the BIG bucks up front, leasing these overly complicated, luxo barges, to worry about the engine overheating or some such thing. That said, the cooling fan running on and on is annoying.

crabman

Of course their gauges move, that is a customer expectation, that they move. But unfortunately as to cynicism, no, that is real knowledge. As I said, I haven't looked at these gauges in particular but I'd if they actually showed a real measurement I'd be more surprised than the more likely pure BS. Switches are cheaper, easier to package, less susceptible to failure, reduce customer interactions, and improve customer experience because they show exactly what customers expect.

This started in the 80s but even earlier with fuel gauges. But let's consider that fuel gauge. Notice how it lingers on full for a while but then goes down at a quicker but regular pace for most of the tank? Notice how it does that on every car? That isn't a coincidences, it does that by design. How about that it goes above full and below empty in most cars; did you notice that? Can the car be fuller than full or still have more fuel when empty?

Gauges have been lying to us for a long time. The water temp is usually going to show something in the 190s on every car now even though modern cars have been running hotter for a quite a while now. But it's a customer expectation so they show the customer what they want to see. This isn't conspiracy theory stuff, it's a known. Remember my Panamera? I can shoot the block with IR and get all kinds of numbers while the gauge says 194, oddly no matter how I drive it gets to that temperature in exactly the same amount of time down to the second. A miracle of engineering and temp controls or do you think maybe a timer is involved?

JSL555

I understand your comments but I think you are conflating the lack of precision of the gauges, which I get, with them essentially being meaningless indicators, or to use your words, “everything the gauge shows is fiction’. Sorry, I don’t buy it.

Baloo588

This happens with my S580 most of the time and every time with the RS7. These engines are powerful and need to be cooled. : )

crabman

The irony here is that you did in fact do exactly that; you've been buying it all along.

JSL555

Touché

Bossanov

This is quite normal. The fan is cooling the turbochargers to prevent the oil form crystalizing thus damaging the turbos.

Streamliner

Well, our E450 Wagon only does it on a rare occasion, on a hot day, after a longer, higher speed drive. Same for our SL450 and for the last couple of S560’s I had. The new car seems to do it all the time. Anyway, I was just curious as to what other W223 drivers were experiencing. I wonder if the W223 I6 behaves the same? Any S500 drivers out there that might comment?

tx170754

Well, my S560 never does it....I'm not driving it very hard but I'm driving it for 30/40 minutes at the time. The A8 4.0T I had did it all the time......

superswiss

The running of the fan when parking the car is very typical for today's V engines that have the turbo(s) nestled between the cylinder banks. The so-called Hot-V setup. This ensures a good response of the turbos, but it gets hot in there, so the turbos need to be cooled. Depends on the engine setup you had/have in your other cars, but I'm guessing they don't have a Hot-V setup. Also a V8 gets hotter than a V6. More cylinders, more explosions per second. But especially in city traffic with constant deceleration and acceleration you are using the turbos constantly, so they are hot afterwards. It should be less likely to happen after a long highway cruise with the turbos not being used for a long period and then parking the car, but even a quick burst of acceleration gets the turbos hot momentarily and if you park it right after then the fan will run to cool things down.

MBS63AMG

My 2022 Audi S8 fans run for a good while after parking. This is the first time I've owned a car that did it so much to notice.

Samarium

My S580 does exactly the same, and I like you had this question in mind. But after reading all these answers, I can put my mind to rest that this is a normal thing.

Samarium

Superswiss, thank you for detailed explanantion.

Lawineer

It's called "afterboil." After you shut your car down, temps spike because there's no air flow and no coolant circulating.
It's why people pop their hoods at the track after running a session. The engine (like, block, pistons, etc) is still hot AF and will heat up the engine bay and fluids. You effectively shut off the cooling system, but there is still a lot of heat.

You'll typically see the highest coolant and engine bay temps AFTER shut down, not during. For obvious reasons, it's more prevalent with turbo engines than NA. Some cars even have auxiliary pumps that pump coolant (but that's probably indicative of poor engine block design). My race car (BRZ) is notorious for overheating coil packs. They would always overheat on my warm up lap. It would happen on hot Texas days and cold days as well. Well, after enough tries, I finally realized they were overheating AFTER my sessions, and as soon as I'd go put some load into my engine where I'd need a strong spark, the symptoms would show. I started popping my hood after a session and haven't had a problem since. I felt particularly stupid because in my previous professional life (~20 years ago) I designed powertrain cooling systems for two different companies :facepalm:

TSA

yes , i experianced this. everything seems to be fine.