Cooling Fan Operation

[BMWRog]

I bought this 2014 M6 at 18 months old with 9000 miles on the clock as a BMW AUC. Even after a smooth, moderate drive, winter time included, the cooling fan would always run on for several minutes after the ignition was switched off. Everything has been going fine, it’s been maintained according to the book, by a BMW approved main agent, and now has 37000 trouble free miles on the clock. The car is completely bog standard - I do change the engine oil and filter a lot more often that recommended by BMW (usually at about 6000 mile intervals), and I almost always fuel it with Shell V-Power 99 RON (octane).

Now all of sudden, it has stopped doing this. Hot day here in the UK on Tuesday, with outside temp up to 28C. Fan definitely revolving whilst engine running, but stops turning abruptly when ignition switched off. Had several trips out since, and it does exactly the same thing. BMW trained mechanic checked diag codes, etc., but no faults found. Oil temperature reads normal at about 105C.

Am I right to be concerned about this fan not running on after ignition has been switched off? Or do you think there was a fault previously which kept it revolving, and now it’s running as it should be?

[MARKPRIOR]

my fan runs after pretty much every journey, does seem odd that it would stop

[Qsilver7]

Are you driving the same route and the same type of driving? Based on the info below from the BMW tech info about the cooling fan...the overrun speed of the fan (after turning the engine is off) is based on coolant temperature & a PWM signal.

It also mentions that the faster you drive, the slower the fan (due to the amount of cooling that comes from air passing through cooling fins of the radiator). So if you are driving faster, and running the air conditioning...this could be lowering the coolant temperature..thus the fan isn’t needed to run at all or as long. Just a thought.

[BMWRog]

Thanks for replies.

I have always, always run the car with a/c switched on - never turn it off. (This is the UK after all! )

The last few trips out have all been relatively local, (on small rural lanes) with not much opportunity to put my foot down. So moderate driving each time in Economy mode but the journeys have been long enough to always get the oil up to working temperature. For the most part, when I return to the house, I leave the engine ticking over whilst I open the garage doors, reverse in and switch off, lock car with alarm set. Every single time up until recently, the fan has always run on for several minutes, irrespective of outside ambient temperature.

Immediately after I have switched off, I can hear what sounds like a softly buzzing relay, as if it won't quite latch. The BMW engineer didn't comment on this, but I gather he thought it might be the electric water pump.

[Qsilver7]

Originally Posted by BMWRog

Immediately after I have switched off, I can hear what sounds like a softly buzzing relay, as if it won't quite latch. The BMW engineer didn't comment on this, but I gather he thought it might be the electric water pump.

Yep...I was going to respond that the buzzing you hear is the electric water pump. The N63TU/S63 engines have three different cooling circuits:

1. Engine cooling circuit
2. Turbo-charger cooling circuit
3. Charge Air/DME cooling circuit

Since the main engine cooling circuit uses a “belt” driven coolant pump that only operates while the engine is running & the electric coolant pump attached to this circuit is used to facilitate heating the interior...the Turbo-charger cooling circuit has its own 20 watt electric pump that can operate up to 30 minutes after shut down to cool the turbo chargers. There’s no need for the main cooling system’s electric pump operation after shut down since it is used to heat the interior. You don’t need to heat the interior with the vehicle shut down unless you initiate the REST (residual heat) feature like when stopped at a railroad crossing when temps are cool/cold...or when running errands in the winter and you want to keep the interior warm since you’re coming back within 15-16 minutes.

There’s a lot of stuff going on under the hood....see the illustrations below that explains the 3 different cooling circuits:

[babaikram]

So a simple question from a novice mind: Which fuse is likely to be the culprit? and where is the fuse box?

[BMWRog]

Many thanks for those detailed drawings showing the 3 different cooling circuits.

I wonder if just one fuse covers all 3 pumps, or if they each have their own separate fused circuits?

Since the engineer ran diags and said 'no problems found', I'm assuming a blown fuse would have shown up as a error. He did say that the ASD module wasn't working, and then I owned up and told him I'd purposely disconnected it!

[Qsilver7]

Originally Posted by babaikram

Which fuse is likely to be the culprit …(for what?)? And where is the fuse box?

Can you be more specific or add some details? It is not clear as to what fuse you are asking about because you don’t mention what your issue is…so it difficult to understand what the culprit could be for an unnamed, unknown, unmentioned situation.

There are two fuse box locations. One is up front behind the glove box…the other is in the trunk (back right corner)...on the f06 you lift up/out the little plastic cubby/pocket….and it reveals the rear fuse box. There should also be a laminated fuse index sheet folded into a slot in the rear fuse box. The fuse index/diagram lists all the fuses by number along with each fuse’s amperage. You also have a diagram that shows the location of each fuse (front and rear). You will also need to learn what the icons are that represent each fuse. BMW stopped using the name, and went to using an icon to represent what the fuse is for. If you look at the icon on the button and switches around the car…you will see they are the same ones used on the fuse index. The owner’s manual also uses the same icons.

{F1 - F67} accessed through panel in glove box


{F100 -F204} rear fuse box

[babaikram]

Originally Posted by Qsilver7

Can you be more specific or add some details? It is not clear as to what fuse you are asking about because you don’t mention what your issue is…so it difficult to understand what the culprit could be for an unnamed, unknown, unmentioned situation.

There are two fuse box locations. One is up front behind the glove box…the other is in the trunk (back right corner)...on the f06 you lift up/out the little plastic cubby/pocket….and it reveals the rear fuse box. There should also be a laminated fuse index sheet folded into a slot in the rear fuse box. The fuse index/diagram lists all the fuses by number along with each fuse’s amperage. You also have a diagram that shows the location of each fuse (front and rear). You will also need to learn what the icons are that represent each fuse. BMW stopped using the name, and went to using an icon to represent what the fuse is for. If you look at the icon on the button and switches around the car…you will see they are the same ones used on the fuse index. The owner’s manual also uses the same icons.

{F1 - F67} accessed through panel in glove box


{F100 -F204} rear fuse box

Thanks. I meant the possible fuse box for the cooling fan that seemed to have stopped working for the OP?

[Qsilver7]

Originally Posted by babaikram

Thanks. I meant the possible fuse box for the cooling fan that seemed to have stopped working for the OP?

Ahhh….thanks for the clarification. I thought you may have had an issue that was similar to the OP’s.