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Discussion Starter #1
Happy Thanksgiving everyone,

It has been awhile since my last post in the forums.

In the past few weeks, I have received one engine overheating message and one engine too hot message. Both of the warnings occurred after approximately an hour of city drive. However, both errors occurred after the car has sat there for few minutes(e.g., restarting the engine after a quick grocery shopping). Errors have never been triggered during normal operating.

I have been monitoring the engine condition in the past few days, and I found that after a short trip(~15mins), the upper radiator hose is really hot, but the lower radiator hose is just a little bit warm(for even shorter distance, the lower hose would just not warm at all). However, after a longer trip(1 hour+), the upper radiator hose is extremely hot, while the lower one is cooler, but still pretty hot.

Today, I have been keeping an eye on the engine temperature in the hidden menu, the operating temperature is ranging from 103 - 107 C(for about an hour period of time)(Which looks normal according to other related threads).

I wonder if anyone has any thoughts about this problem? Could it be a failing thermostats or water pump? Any input is welcome!

Thank you!
Singer
:)
 

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2006 530xi 6 MT
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Well, something is wrong in the cooling system. Given the age of the car, if you don't have any knowledge of the water pump and thermostat being recently replaced, I'd replace them both now and flush the cooling system.
 

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Discussion Starter #3
Well, something is wrong in the cooling system. Given the age of the car, if you don't have any knowledge of the water pump and thermostat being recently replaced, I'd replace them both now and flush the cooling system.
Thank you for your reply. I don't believe the water pump or the thermostat has been changed at least in the past two years or so. But is there any specific way I could find out what is possibility going wrong before replacing any parts? Thanks!
 

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Those are the EXACT symptoms when the electric cooling fan quits. Fan operation needs to be verified. You may or may not have a cooling fan code stored on a 2004 as I recall if the fan controller is signaled for fan running but fan motor does not actually run..
 

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Discussion Starter #5 (Edited)
Those are the EXACT symptoms when the electric cooling fan quits. Fan operation needs to be verified. You may or may not have a cooling fan code stored on a 2004 as I recall if the fan controller is signaled for fan running but fan motor does not actually run..
Thank you so much for your information.

That makes perfect sense to me. And explained why I could drive an hour+ without overheating warnings. As I recall, the fan was able to run at a very high speed, but as mentioned in other related threads, there might be malfunctions with the controller unit and/or the temperature monitoring sensor? I have scanned the car for any errors but came up nothing(I was using a generic code scanner, not specific for BMWs). I wonder if there is any proper procedures to diagnose the fan operation?

Thank you!:thumbup:
 

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In the past few weeks, I have received one engine overheating message and one engine too hot message. Both of the warnings occurred after approximately an hour of city drive. However, both errors occurred after the car has sat there for few minutes(e.g., restarting the engine after a quick grocery shopping). Errors have never been triggered during normal operating.
Makes sense. That's the hottest time for an engine. As long as the engine is on it is cooled by the colder, circulating coolant. Once you stop it, the coolant circulation stops and the still hot cylinders heat up the coolant that is trapped around the cylinder wall.

So it's either the engine runs hotter than it used to be (lean air fuel mixture) or the cooling system is insufficient. Like the fan as Aber mentioned.
 

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Discussion Starter #7 (Edited)
Makes sense. That's the hottest time for an engine. As long as the engine is on it is cooled by the colder, circulating coolant. Once you stop it, the coolant circulation stops and the still hot cylinders heat up the coolant that is trapped around the cylinder wall.

So it's either the engine runs hotter than it used to be (lean air fuel mixture) or the cooling system is insufficient. Like the fan as Aber mentioned.
Thank you very much for your reply. I just did some testing with cold engine:

1. Start the car with A/C off -> Fan did not come on;
2. Start the car with A/C on -> Fan did not come on;

3. Start the car with the unplugged temperature sensor on lower radiator hose -> Fan came on at full speed.
4.Start the car with A/C on -> Fan did not come on.

Is this an indication of a good fun, but a bad temperature sensor?

Thank you!
 

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Hmmm...I assumed the fan was working. You got it to turn on, so you know the fan works. I don't understand why it doesn't come on with the A/C when you start the car, I thought that forced it to start. Why about just idling in the driveway for 10 minutes? That should get the fan to come on I would think. I also think INPA can for the fan to come on.
 

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Discussion Starter #9 (Edited)
Hmmm...I assumed the fan was working. You got it to turn on, so you know the fan works. I don't understand why it doesn't come on with the A/C when you start the car, I thought that forced it to start. Why about just idling in the driveway for 10 minutes? That should get the fan to come on I would think. I also think INPA can for the fan to come on.
Thanks for your reply, I will try to let the car idle until the engine reaches its operating temperature. Unfortunately, I don't have the INPA tool available. But it appears the fan is working(at least in some way).:tsk:
 

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Discussion Starter #10 (Edited)
Thanks for your reply, I will try to let the car idle until the engine reaches its operating temperature. Unfortunately, I don't have the INPA tool available. But it appears the fan is working(at least in some way).:tsk:
So, I just came back testing the system.

Have the following behaviors were observed:

1. The fan did not come on while the car is cold;
2. A/C did not have any heat until the engine temperature reaches 50C;
3. The fan came on from time to time but does not seem to relate to the A/C;
4. Either the fan or the thermostat(because the lower radiator hose started to get warm(much cooler than the upper one), I was assuming the thermostat opened to allow coolant come through) will bring the temperature down to 102C once it reaches 105C;
5. After idling for more than 20 mins, shut off the engine and the temperature drops.

It looks like everything is working except the A/C and fan part. Any thoughts?
 

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So, I just came back testing the system.

Have the following behaviors were observed:

1. The fan did not come on while the car is cold;
2. A/C did not have any heat until the engine temperature reaches 50C;
3. The fan came on from time to time but does not seem to relate to the A/C;
4. Either the fan or the thermostat(because the lower radiator hose started to get warm(much cooler than the upper one), I was assuming the thermostat opened to allow coolant come through) will bring the temperature down to 102C once it reaches 105C;
5. After idling for more than 20 mins, shut off the engine and the temperature drops.

It looks like everything is working except the A/C and fan part. Any thoughts?
Ok, fan does run when you unplug sensor, fan does not come on when AC IS ON AND CAR IDLES. However as I understand the fan should come on when:
1)
AC is on and
2)
Engine is at operating temperature and reaches the top end of operating temp.

Those are the two conditions as far as I know and that is the way my fan operates, in other words at cooler ambient temperature we are now beginning to experience you wil have to get close to the overheating range for the fan to be switched on by the sensor as that is not happening I would replace the sensor.

I have been looking for the section of wiring diagrams that cover the fan circuit but ran out of time, just to verify that the sensor needs to open the circuit for the fan to run as that will prove my theory......
 

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Discussion Starter #12 (Edited)
Ok, fan does run when you unplug sensor, fan does not come on when AC IS ON AND CAR IDLES. However as I understand the fan should come on when:
1)
AC is on and
2)
Engine is at operating temperature and reaches the top end of operating temp.

Those are the two conditions as far as I know and that is the way my fan operates, in other words at cooler ambient temperature we are now beginning to experience you wil have to get close to the overheating range for the fan to be switched on by the sensor as that is not happening I would replace the sensor.

I have been looking for the section of wiring diagrams that cover the fan circuit but ran out of time, just to verify that the sensor needs to open the circuit for the fan to run as that will prove my theory......
Thank you for your reply.

I think the sensor might not be malfunctioning as the fan does turn on and off while idling with the A/C off. And the engine temperature is always staying under 105C(which I read somewhere to be the normal operating temperature of these engines).

I am not sure why the fan wasn't come on while the A/C is on. The interesting fact to note is that the engine only randomly overheats(happened twice in the past few weeks) after shutting off.

Cheers!
 

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Sensor may have an intermittent failure sometimes.
 
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