[Idaho335D]

My wife drove the car on the highway for about an hour then it sat in the driveway in 50*F temps for about 10-15 minutes. I got in, let it idle a minute and coolant temp was 70*C. Drove it hard for 5 minutes including a quick run to 100mph (closed course obviously). Hottest I saw during the run was 77*C. After I turned around coming home and ran it in 2nd gear about 4K rpms for about 30 seconds up a hill giving it throttle the whole time and it flashed a 95*C but stayed about 90*C the rest of the time. Think I need a thermostat? Car has 108k miles.

[Owen81]

It should be pretty steady at 85-90C on the highway depending on the ambient temps, and go slightly above if you are putting extra load on the engine.
If you are not seeing this then I would replace the Tstat

[Persian Whisperjet]

Originally Posted by Owen81

It should be pretty steady at 85-90C on the highway depending on the ambient temps, and go slightly above if you are putting extra load on the engine.
If you are not seeing this then I would replace the Tstat

Second that. AA Rodriguez was selling the part for ~$25.

[AlpineX]

Originally Posted by Idaho335D

My wife drove the car on the highway for about an hour then it sat in the driveway in 50*F temps for about 10-15 minutes. I got in, let it idle a minute and coolant temp was 70*C. Drove it hard for 5 minutes including a quick run to 100mph (closed course obviously). Hottest I saw during the run was 77*C. After I turned around coming home and ran it in 2nd gear about 4K rpms for about 30 seconds up a hill giving it throttle the whole time and it flashed a 95*C but stayed about 90*C the rest of the time. Think I need a thermostat? Car has 108k miles.

Definitely a thermostat. There is a main thermostat and a 2nd thermostat on the transmission heat exchanger (almost no additional labor). I didn't change my 2nd thermo, wish I had (wasnt able to get the part in time, didnt realize it would be a special order).

Before the car reaches 75*C under normal operating conditions, the glow plugs are operating in "warm up mode". If you are spending a lot of time under 75*, your glow plugs are working overtime.

[Torqu3]

Originally Posted by AlpineX

Definitely a thermostat. There is a main thermostat and a 2nd thermostat on the transmission heat exchanger (almost no additional labor). I didn't change my 2nd thermo, wish I had (wasnt able to get the part in time, didnt realize it would be a special order).

Before the car reaches 75*C under normal operating conditions, the glow plugs are operating in "warm up mode". If you are spending a lot of time under 75*, your glow plugs are working overtime.

e90 335d in North America only have one thermostat.

[AlpineX]

Originally Posted by Torqu3

e90 335d in North America only have one thermostat.

Thought it was all US M57,not just X5. Thanks for clarification.

[Miko226]

Originally Posted by Persian Whisperjet

Second that. AA Rodriguez was selling the part for ~$25.

+2