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Discussion Starter #1
What temperature should the electric radiator fan cut in/out on a 2004 e46 320d

A few note of whats been checked, changed or noted.

The car gets up to 88 to 91 deg C on obd display during a run.

Main thermostat changed, system bleed with fresh coolant

With the car sat idleing for quite some time (20mins ish) the temp slowly rises as expected. I let the temp get too 99 deg C but still the fan had not cut in

Only thing i know for sure is that the thermostat opens at 88 deg C.

The fan cuts in and out if i put the A/C on so i know the fan works .

Have seen a few posts that mention the control unit that is on the fan bracket can cause the fan too not run.

Have spent the last 2 hours searching on the net trying too find out what temperature the fan should be cutting in but cannot find anything.
So can anyone tell me at what temp the electric rad fan should cut in/out.
 

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are you looking at the fan at the front of the car? this is the aircon fan. The rad fan will be the viscous one on the front of the engine :thumbsup
 

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I have noticed the same thing on mine 320d touring 2004, just changed both stats and working perfect now but there is no viscous fan on the front of the engine, just the one electric fan on the front of the radiator behind the vacuum controlled "blinds" and i have never heard it running ..I did notice when I bought auxillary belts for it this week the air con belt shown on mine (car build date of 11/04) was a stretch belt with no tensioner but when i got to it there was a tensioner on it so the engine build date is pre 09/04, but definately only the one electric fan ..:confused:confused:confused
 

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It looks like the blinds are vacuum controlled but what controls when they open and close as mine seem to be permanentely open ? cant help you on what temp the fan comes in chiffs as it never gets as high as 99 on obc, seems to get to a max of 94.
 

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Discussion Starter #7
Blinds are vacuum controlled.

My blinds are shut untill the engine is switched off. Not seen them open yet when running. Was thinking around 95 ish should be about the temp the fan should cut in.
 

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Only ever looked at them with engine switched off so they could be shut when its running, mid 90's seems reasonable for fan to cut in but ive never heard mine either so cant help you on that, only did both stats at weekend, (wasnt getting above 74 degrees) egr stat was goosed , you could blow straight through it and was getting 35-36 mpg on a run..temp bang on 12 o'clock now and running at 90-92. went on a run yesterday and obc showed 51mpg so more than pleased ( I know its not accurate but in comparason to showing 36 !! )
 

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Discussion Starter #9
Alan I was running at 79-82 max, now have the same temp as yourself after changing main thermostat. Not done a long run yet but after 30 min drive was sitting around 90-91 deg C.

Could you have a check on your flaps at some point soon just too see what they are doing when running please?
 

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will do, I was wondering what controlled the vacuum actuator that opens and closes them if you know what I mean, there must be some type of temp sensor that operates the vacuum unit, maybe this is linked to the fan switching on at the same time as they open ??? anybody ???
 

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Got it, so its an electric valve that opens and lets the vacuum through in effect, that valve must be linked to a temp sensor somewhere or to the fan control unit. just looked on mine and when you switch the ignition on the blinds close.
 

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Discussion Starter #13
Same as mine then, air can still escape through the bottom towards the ground as there is no underpan inside the rad blind bit.

Maybe they just open when you switch off to allow easier cooling
 

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Discussion Starter #14
Found out from BMW today that the fan should cut in at 98 deg C.

Think the control side of things for my fan are fooked maybe:frown
 

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Might not be fooked, there will be a tolerence of a couple of degrees I would think and you only got yours to 99 deg did you say ? I believe its the same rad as they put on the 330d and is capable of cooling a 3.0 so I would think you would need extreme conditions for a 2.0 to get it up to the temp where the fan cuts in.
 

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Discussion Starter #16
Managed 100 deg C today and still no fan cutting in:mad. Does take a long time too get there though and dont really want too get it any hotter waiting for the fan too maybe not run.
 

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If you have a only one electric fan, it does for the aircon and engine cooling. If it is a Siemens fan, I have seen several of these fail, including mine. All the electronics are in the centre of the fan and dont get any cooling unless the car is moving, so some of the transistors overheat and fail. It tries to move when engine cooling demands it, but cant, it just wobbles from side to side. New ones have their electronic box to one side, and gets some cooling from the fan.
 

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Discussion Starter #18
Little update.

The fan does cut in, wahoooo.

Had the garage check it out. They used a little remote temp gun thing which with the obd showing 99 deg C showed the following.

Water out of the engine was 97 deg C on the hose, by the time that got too the rad it had dropped around 7 deg C. Without the fan running and just the water flowing through the rad it had dropped another 10-14 deg C.

So all in all the BMW cooling system is very efficient and works very well.

The fan cut in at 100 deg C only for a very short time 5-10 seconds and dropped the obd temp by 2 deg C but on the engine water outlet pipe this reduced from 97 deg C to 91 deg C.

All in all happy in the knowlegde that my fan still works fine :)
 
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