35D not getting up to temp
 

Hey everybody, I bought my 2010 35d about 3 months ago and I've been very pleased with it so far. Today I started experimenting with the hidden menu and decided to monitor coolant temp on my way home from work which is about a 30 mile drive. The outside air wasn't terribly cold at 42 degrees Fahrenheit. My entire drive home the coolant temp sat right in the mid-sixties Celsius. I saw it break 70 one time after a hard acceleration up a Long Hill, and while coasting downhill it would drop into the fifties.

The entire 30 mile trip never resulted in a coolant temp that even reached 160* F. Do I possibly need to replace my thermostat?

Yep. Bad thermostat. Happened to my 4.8 at 80k miles.

Common issue - seems to have greater ramifications for diesels than gas - check it out here:
https://xoutpost.com/bmw-sav-forums/...-diy-pics.html

Good thing it stuck open and not closed!

Had mine done about 2 months ago. Book time on the thermostat is about 3.5hrs.

Cost me $550 all-in w/ my Indy ($95/hr labor).

I'd have gone about it myself, but the EGR cooler sits right there over the thermostat on the M57. Just more than I wanted to chew off at home in my garage. It's easier on the gassers.

Thanks guys, I'm ordering one today and I will do it myself.

Its probably your main thermostat but... worth a try to look into EGR cooler thermostat first since it also fails and its so much easier and cheaper to change.
Part #8 on here: RealOEM.com - Online BMW Parts Catalog

https://www.youtube.com/watch?v=ZhtfKliAkiU

reaching and maintaining operating temperature is crucial for proper DPF regeneration . bad thermostat is common and will result is blocked DPF. 35D doesnt have a thermostat on egr cooler but instead a divertor valve inside with a vacum actuator. make sure divertor valve moves freely. if your motor hasnt been reaching proper temp for a while due to bad thermostat. you probably have a seized divertor valve as well .you can lube it and free it up you have to remove egr cooler to change thermostat anyway.

Thanks for the heads up, I will check that.

Glad you got the answer about the bad thermostat. Off topic but do you have to keep accessing the hidden menu each time you want to check the coolant temp or is it shown forever when you unhide it the first time?