I'm not sure if this is where my coolant leak is coming from, but the bottom half of it is damp from what I believe is the coolant I've lost. It's circled in yellow in the attached picture and has a tube/pipe that runs to the driver's side of the engine bay.


Any help is greatly appreciated.

Thanks!

 

Vacuum pump

 

Thanks. I'm gonna assume that's not where my leak is coming from then. Hmm.

 

thats the vacuum pump, and they are known for leaking oil.
i had a mysterious coolant leak also. check your lower radiator hose where it attaches to the radiator, there is a coolant sensor that plugs in there, and the o-ring for it is known to leak. check while car is warm, since the leak is slow enough, that it evaporates and doesnt hit the ground.

 

Awesome, that helps a lot. I'll do just that. Thanks!

 

Looks like there is an oring that seals the pump to the upper timing cover. This might be cause of an oil leak.

 

I just Googled that after reading your reply. Looks like I'll have to order an o-ring kit for that one, too. Thanks again!

 

Also check the coolant expansion tank vent pipe that runs along the top of the radiator. The hard plastic portion of the pipe develops cracks. I just replaced mine on my 08 550i, because it suddenly failed.

 

Been there, done that on my 05. fixed it by replacing the 05 with a MY 2010 Msport

 

That's a rather expensive fix in lieu of replacing a $40 part.