Another leak w/picture
 

I have seen a lot of threads about leaks recently and now I have one too. It only happens when it gets really cold out I'd say 20 deg or less. The car does not leak in the garage overnight. When it does leak I have 2 spots that are suspect. Not sure how to fix them. I have marked in the picture the 2 items that are wet when I spot the antifreeze on the ground. If anyone can shed some light that would be super! Thanks!

https://www.dropbox.com/sh/ir3m0ne468qmkci/vUJi26mGXl

Any ideas if this might be an O ring of maybe a sensor of hose issue?

Looks like you need either #1 or #3 in the below picture. Usually the o-ring is part of the hose.

http://www.realoem.com/bmw/diagrams/i/m/239.png

OK I could see those possibly being the issue. I also see saw some moisture around the connection of part number 16 in that picture. Maybe I'll start with your suggestion. I just checked some prices for the hoses. Where is the best place to the drain for the coolant? I cant seam to find a petcock. The X5 is probably due for a flush anyhow. Thanks again!

Remove the plastic cover under the front of your X5. I believe all of the bolts are 8mm. Then you should see a blue drain plug on the radiator (driver's side of the X5). You'll need to remove the radiator cap as well.

alternator?
 

The alternator has a big rubberband around It to, ECS tuning has the hoses and gaskets .And number 16 gasket is a easy fix those do go bad a lot ,You can replace the sensor and the o-ring or just the o-ring.....it pops right Good Luck:D

Should I do the lower and upper along with the sensor or Is there anything else I should throw in as well?

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Depends...whats your mileage and history. If its been a while (100k miles), change the coolant, upper and lower radiator hoses, coolant temp sensor, thermostat with housing, and possibly heater hoses.

It's right at 97k miles. Sounds like a good weekend project this darn X5 is full of those!!