[fastandthecurious]

Hi guys



I've got a E90 320i (N46 Engine). Recently, I had to change the thermostat housing as the seal was leaking coolant, during which I had to disconnect the thermostat. After putting everything together, I decided to check the coolant temperature via the hidden dash menu and INPA and saw some concerning readings. After a short drive around the block, the coolant temperature steadily increased and reached 109 degrees celsius before I shut it off. On my previous cars (not BMWs), +/- 90 degrees was normal and over 100 degrees would be classified as overheating. On INPA, there is another block "coolant output temperature" in addition to the "coolant temperature" which remained at around 46 degrees celsius. When I checked under the hood, the upper radiator hose was significantly hotter (burn to the touch) than the lower radiator hose, which was warm. There was no thermostat related codes when I scanned the car with INPA and no dashboard warning lights.

I've never really paid attention to my coolant temperatures before this, so is this normal? What temperature does the thermostat usually open at, being electronically controlled? If the thermostat wasn't plugged in properly, would the car throw an error code at all? Is there any way to manually open the thermostat via INPA or something to test that it is working?

I'm really scared of blowing a head-gasket. Any advice is appreciated!

Thanks

[Volasko]

I can't speak for the N46 engine but if it uses a electric water pump like the N52 it could be a normal coolant temperature. See page 67 of this document to read about the different coolant setpoint maps BMW engineered into our cooling system that vary depending on engine load:

https://drive.google.com/open?id=0B8...a&usp=drive_fs

[fastandthecurious]

Originally Posted by Volasko

I can't speak for the N46 engine but if it uses a electric water pump like the N52 it could be a normal coolant temperature. See page 67 of this document to read about the different coolant setpoint maps BMW engineered into our cooling system that vary depending on engine load:

https://drive.google.com/open?id=0B8...a&usp=drive_fs

Thank you. The N46 uses a mechanical waterpump but an electric thermostat (same like N52). Do you know if these cars will throw an error if the thermostat was not plugged in properly?

[F31B48]

Originally Posted by fastandthecurious

Thank you. The N46 uses a mechanical waterpump but an electric thermostat (same like N52). Do you know if these cars will throw an error if the thermostat was not plugged in properly?

Yes it should log a code if its not cnnected properly. Try disconnecting it then reading the fault memory with INPA. It is normal for BMW engines to run at 110c under certain conditions, sometimes up to 120.

For driving conditions with low loads, the mapped thermostat sets a high coolant temperature (efficient consumption). For full loads or higher engine speeds, the coolant temperature is reduced to protect the components

The "coolant output temperature" you were seeing in INPA refers to the sensor on the bottom outlet of the radiator. Being lower than the engine temperature is good and indicates the radiator is actually cooling properly.

Are you certain you bled the system of air properly and have you used the correct ratio of coolant to water??

[aphael]

Originally Posted by EvaBmw

Yes it should log a code if its not cnnected properly. Try disconnecting it then reading the fault memory with INPA. It is normal for BMW engines to run at 110c under certain conditions, sometimes up to 120.

For driving conditions with low loads, the mapped thermostat sets a high coolant temperature (efficient consumption). For full loads or higher engine speeds, the coolant temperature is reduced to protect the components

The "coolant output temperature" you were seeing in INPA refers to the sensor on the bottom outlet of the radiator. Being lower than the engine temperature is good and indicates the radiator is actually cooling properly.

Are you certain you bled the system of air properly and have you used the correct ratio of coolant to water??

the 110-120c you are referring to is oil. Water is definitely not supposed to be above 100c. If I remember correctly optimum temperature is around 95-100. At 120 its 248F which means the coolant will definitely be boiling by then even with an antifreeze mix and pressure. The oil is normally able to go to 250f in economy mode.

[fastandthecurious]

Originally Posted by EvaBmw

Yes it should log a code if its not cnnected properly. Try disconnecting it then reading the fault memory with INPA. It is normal for BMW engines to run at 110c under certain conditions, sometimes up to 120.

For driving conditions with low loads, the mapped thermostat sets a high coolant temperature (efficient consumption). For full loads or higher engine speeds, the coolant temperature is reduced to protect the components

The "coolant output temperature" you were seeing in INPA refers to the sensor on the bottom outlet of the radiator. Being lower than the engine temperature is good and indicates the radiator is actually cooling properly.

Are you certain you bled the system of air properly and have you used the correct ratio of coolant to water??

Yes I did bleed the system with the 2 bleed screws in the engine bay (by the reservoir and oil cooler).

I checked the car out again this morning by letting the car idle & gave a couple of revs. Coolant temp increased linearly from 25C to 108C just from sitting and idling after a while, at which point the fan started kicking in but the lower radiator hose was still just "warm" compared to the upper which was boiling hot. There was still a big difference between the coolant temp and the coolant output temp even though the car was just sitting idling with no air cooling?

I also tried unplugging the thermostat, cold started the car and let it idle for 15 min. Surprisingly no errors came on the dash or in INPA? Will it only trigger a code at the instance when the ECU wants to open the thermostat or should it trigger right away when you start the car?

At this point I have no idea whether the thermostat is working or not lol. Are there any tests to confirm if these electric thermostats are good or bad with INPA or a multimeter or something?

[fastandthecurious]

Originally Posted by aphael

the 110-120c you are referring to is oil. Water is definitely not supposed to be above 100c. If I remember correctly optimum temperature is around 95-100. At 120 its 248F which means the coolant will definitely be boiling by then even with an antifreeze mix and pressure. The oil is normally able to go to 250f in economy mode.

Yeah that's what's making me concerned. 108-110C+ seems very high for water temp at 25C ambient room temp. On my previous cars (VW & Toyota), 120C would be in the red zone on coolant temp gauge and normal temp was around 90-95C.

Is there a way to test if these electric thermostats are working besides replacing it and comparing the before and after temps?

[F31B48]

Originally Posted by aphael

the 110-120c you are referring to is oil. Water is definitely not supposed to be above 100c. If I remember correctly optimum temperature is around 95-100. At 120 its 248F which means the coolant will definitely be boiling by then even with an antifreeze mix and pressure. The oil is normally able to go to 250f in economy mode.

Wrong! Here is the functional description copied straight from ISTA regarding coolant temperature ranges and operating modes.

The engine control unit regulates the following temperature ranges:

112 C = Economy105 C = Normal95 C = High80 C = High and regulation by the map thermostat

If the engine control unit detects the economical operating range ”Economy” due to the driving characteristics, the DME regulates to a higher temperature (112 °C). In this temperature range, the engine is operated with a relatively fuel requirement. The friction inside the engine is reduced at higher temperature. The temperature increase thus favour the lower fuel consumption in the low load range.

In the mode ”High and control by the map thermostat”, the driver wants to use the optimised power output development of the engine. To achieve this, the temperature in the cylinder head is lowered to 80 C. This reduction leads to better cylinder filling, which increases the torque of the engine. The engine control unit can now regulate to a certain operating range adapted to each driving situation. This means is it possible to influence consumption and power output by means of the cooling system.

[fastandthecurious]

Originally Posted by EvaBmw

Wrong! Here is the functional description copied straight from ISTA regarding coolant temperature ranges and operating modes.

The engine control unit regulates the following temperature ranges:

112 C = Economy105 C = Normal95 C = High80 C = High and regulation by the map thermostat

If the engine control unit detects the economical operating range ”Economy” due to the driving characteristics, the DME regulates to a higher temperature (112 °C). In this temperature range, the engine is operated with a relatively fuel requirement. The friction inside the engine is reduced at higher temperature. The temperature increase thus favour the lower fuel consumption in the low load range.

In the mode ”High and control by the map thermostat”, the driver wants to use the optimised power output development of the engine. To achieve this, the temperature in the cylinder head is lowered to 80 C. This reduction leads to better cylinder filling, which increases the torque of the engine. The engine control unit can now regulate to a certain operating range adapted to each driving situation. This means is it possible to influence consumption and power output by means of the cooling system.

I just asked my mechanic now and he says these thermostats only open at 105C so I guess it's normal then as everyone has advised. To trigger the ”High and control by the map thermostat”, do I just drive the car hard after it's gotten to operating temp for the ECU to activate lower temps for optimised performance?

I also read somewhere that these thermostats open mechanically regardless at 105C and the electrical component is only there for when the ECU wants to open the thermostat at temps below (105C) the one that the mechanical part of the thermostat is rated for (e.g. 80C) and thus uses a heating element to do this. Is this correct?

[Nikola090]

greeting!
I have a bmw e90 2006 year 320i n46b20 engine
I have a problem with the venting of the cooling system. The engine has a mechanical water pump and an electric thermostat. I am interested in how many volts should be on the connection for the thermostat?
mine is 9.12v when the key is in contact. should it always be 12, except when the dme is under load, it sends a signal for 14.3v?

Nikola.zmuk@gmail.com
Croatia

[Shadyz]

I had the same thing . I had a hole in the arm of the radiator . I changed all tge coolant pipes and radiator and thermostat to original bmw new . I connected the obd and got a heart attack I thought tge headgasket was blown . Then a drain plug of the radiator blew up but this was because i took from the old one and i broke the pins so i got more heart attack . But then i seen that the tempreture rises to 110c and just the fan works but the thermostat dosent open . So I said fuck it . The worst that can happen is a blown engine i crossed my heart and drove from austria 1700 km in 2 days . Tge thermostat was working fine untill you stop then the tempreture rises again to 110 then you go 200 Km/h and the coolant temp is about 90 . So what the guy wrote about economi and high and normal is correct .