It appears I have a coolant leak by the bottom passenger side of the radiator right before the main hose clamps on. There seems to be some kind of wire harness/sensor and the leak appears to be coming from that sensor. Anyone experience a similar leak or know the part number of this thing? See attachment...

 

too common. It cost me $125.00 to have it replaced. there is another temperature sensor on top of the radiator as well.

 

Very common leak point. That is the coolant temp. sensor. Quick, easy and cheap DIY.

 

Thanks for the replies! How would I go about replacing this? Do I have to drain out all the coolant? How does it attach to the radiator?

 

I got lucky and di not have to drain the coolant. I just left it parked in the garage for a few days until the part was ordered. Leave the Coolant Cap On! Do not open or it will release the coolant back into the lines and you will lose a lot. I was able to swap out pretty quick and only lost a few drops. You could also drain the coolant if you want, but it was not necessary. Either way, be prepared for a cleanup just in case. If you search there was a recent thread on this. I think it was started by Quarta2Six.

Found it:

https://5series.net/forums/e60-discu...-loose-140857/

 

Not sure what model you have but you can just buy the replcement sensor which comes with the O-ring 3 minute DIY job. OR you can purchase the O-ring itself from ECS cost a $1. Most just replace the sensor, mine was fine and I was already purchasing items from the site so I threw it in my cart. BMW E60 545i N62 4.4L Search SiteSearch 13621433077 - ECS Tuning part number may be different for your car not sure. No, you dont have to drain all the coolant out if you do it when the engine is cold atleast sitting overnight you should only loose a few drops of coolant if that (just did this a month or so ago) the sensor simply clips into the rad hose MAKE SURE you leave the coolant reservoir cap on good tip another member told me.

 

 

After some searching I see how common this problem is. I think I'll try replacing just the o-ring and see what happens. Thanks for all the good info and tips!

 

Pays to read a little bit slower didnt even noticed you posted all of that right before me, lol....

 

LOL! No worries brother! It's all about helping one another out.