[niksss]

Hello guys ! I drive a 2012 BMW E92 328i X-Drive with the N51 engine. When winter came I noticed that the car has little to none heat coming from the vents. I checked the coolant temperature and it was low. When driving in the city it heats up very very slowly and never goes above 70-75 degrees. When driving on the highway the coolant heats up to around 100-102 degrees and there is heat coming from the vents, but I remember in the summer the coolant temp was arond 112 degrees on the highway. When driving on secondary roads with 80-100km/h the temperature may drop to even 40-50 celsius.

Today I let my car idle for 15-20 minutes and it got up to 102 degrees. I started driving and the temp was ok (99 to 104 degrees) and there was a lot of heat from the vents. I stopped to get some food and to eat (left the car running) and when I came back (around 5-10 minutes) the temperature of the coolant was 54 degrees and the vents were blowing very cold air. Also fuel consumption seems worse.
The temperatures outside are around 3-7 degrees, so it is not that cold.

So far I have replaced my thermostat which made no difference. What may be the cause ? I have no codes when scanning with ista.

One thing that I have noticed is that the radiator fan is running even when the temperature outside is very cold (0-2 degrees) and the coolant temp is around 70. Is this normal ?

P.S.: All degrees I mentioned are in celsius.

[Volasko]

Hmmm the first thing I would have said is failed T-stat, but you mentioned you already did that. Did you JUST do the swap or was it done before. It is not impossible that a new part fails quickly especially if you go after market. It could be the water pump about to fail (intermittent operation) but usually it is all or nothing, and when it does you'll know pretty quickly even in cold temps. When mine failed it was the dead of winter in Canada and even thought it was -10 deg C outside it could only limp it home in 5 minute increments before I needed to stop and let it cool.

[MightyMouseTech]

Have you scanned the car? Sounds like a failing water pump.

[niksss]

Originally Posted by MightyMouseTech

Have you scanned the car? Sounds like a failing water pump.

As I have mentioned in my first post, I have scanned it several times. No errors in the DME. I am not sure, but if the pump is failing wouldn't it overheat, not overcool the coolant ?

Originally Posted by Volasko

Hmmm the first thing I would have said is failed T-stat, but you mentioned you already did that. Did you JUST do the swap or was it done before. It is not impossible that a new part fails quickly especially if you go after market. It could be the water pump about to fail (intermittent operation) but usually it is all or nothing, and when it does you'll know pretty quickly even in cold temps. When mine failed it was the dead of winter in Canada and even thought it was -10 deg C outside it could only limp it home in 5 minute increments before I needed to stop and let it cool.

I changed the thermostat 5-6 days ago in order to fix this issue. There was no change in the temperatures before and after replacing it. If the pump is failing I guess I would have a code, which I don't.

Thanks for trying to help guys !

[rjahl]

If I were you, I'd fire up INPA and watch the fuel pump PWM, Radiator PWM, requested thermostat position along with the related coolant temperatures. Under normal situations the DME controls and monitors all of these items.

The clues to your problem will be in this data.

BTW, IF the DME recognizes a failing water pump, it sets the pump and radiator fan speed to maximum but that's easy to recognize and should throw a code.

[niksss]

Originally Posted by rjahl

If I were you, I'd fire up INPA and watch the fuel pump PWM, Radiator PWM, requested thermostat position along with the related coolant temperatures. Under normal situations the DME controls and monitors all of these items.

The clues to your problem will be in this data.

BTW, IF the DME recognizes a failing water pump, it sets the pump and radiator fan speed to maximum but that's easy to recognize and should through a code.

Good idea, I will. Also I forgot to mention that I have changed my radiator just before the winter, because my old one was leaking. Could this be the culprit ? Before the radiator replacement I had heat from the vents but the temperatures outside were higher.

[rjahl]

Originally Posted by niksss

Good idea, I will. Also I forgot to mention that I have changed my radiator just before the winter, because my old one was leaking. Could this be the culprit ? Before the radiator replacement I had heat from the vents but the temperatures outside were higher.

Is the new radiator on OEM replacement?

[niksss]

Originally Posted by rjahl

Is the new radiator on OEM replacement?

It’s not OEM because my radiator is the one with the expensive coating, but it is a reputable brand (NRF), not some chinese one.

[niksss]

Changed the radiator outlet coolant sensor. Still not heating up :/