Thermostat Malfunction?
 

So while chasing down an erratic engine temp issue, I arrived here. It all started with an upper radiator failure. Got stranded, nursed it home with gallons of distilled water bought from a nearby Walmart. Got home replaced hose, then on way to work next morning engine temp went to 3/4 on gauge, stayed then dropped to normal like a rock. On the ride home that evening, engine temp stayed normal for a bit, then rose to just over 3/4 on gauge and stayed there. I nursed it home and parked it... this is what I found today. The t_stat on the left of course is the one I removed from my "X". Has to be changed, yes I know, but you think this would cause my erratic engine temps?

Absolutely. Also, the gauge doesn't show relative engine temp so it was probably long time in the works as the gauge will report "perfect health" with temps 15-20C lower than ok.

I have the 3.0 Diesel turbo and the temp gauge is very much only just in the okay range. So on the left you have the blue section. then the | and my temp sits above that and sometimes it goes up to the half way mark if driven hard. Is my thermo up the creak or do I not need to worry and this is normal.

I'd replace it if I was you, easy enough to do on the M57TU diesel. A few members have done it recently, including myself. There is a good write up here with pictures, provided by wpoll. You'll get your engine back operating in the correct temperature range with more efficient combustion, fuel economy etc. Have some coolant on hand as you'll lose some during replacement and bleed the system to be sure all air is gone.

Cheers Neil,

Good info and I will get on it and find wpoll's post.

Sorry Lamby, I could have made it much easier:

https://xoutpost.com/bmw-sav-forums/...ml#post1079662

Top man, thanks. I will have already ordered the Part from BMW. Okay its £55 but to be fair thats only about £8 more than the one I was going to buy from Euro Car Parts. And.... I saved on a Non OEM door carrier that worked out okay in the end. After I didn't clip the plastic ball joint of the cable to the protruding pin... anyway... next win is the thermostat

Tip on the t-stat: to remove the fan use a 1-1/4 open end wrench and smack it with a hammer. Look for YouTube video. The radiator hose stops the wrench.

There are some out there that tell me that I don't need to remove the fan on teh M57TU - which is the one I have? Is this bogus? Should I do it anyway?

If you had the proper scanner, you could have scanned the X and it might have logged a trouble code with the thermostat. My X drove normal in the summer, but in the winter it took quite awhile for it to reach operating temp. Scanned the X with Carsoft 6.5 as well as BMW Scanner 1.4 and got a trouble code for the thermostat being stuck open.