Is my thermostat working?

[thefastandthecurious]

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

 

[Steph745]

Not sure if this will help... but does the n46 in the e90 also have an electronic thermostat like the n52/4/5? When I had an e90 323i temps were as follows;

- Steady speed low throttle in 6th (eg highway) - 98-103 deg
- Traffic - 106-112 deg
- Full throttle/high demand - 80-83 deg
- Extended idle - 110-114deg (then fan would kick in till temp drops to about 108/109)

I never once got a temp warning in 4 years of driving it, I think overheating is 116 +. If I'm not mistake the electronic thermostat has 4 operating maps.

 

[DarrylvanNiekerk]

Something to note is that you also have a coolant temperature sensor on the block as per the pic below, maybe that was the higher temp reading you were getting?