Anybody know where this hose goes?
 

It's hose number 3 in this diagram (2003 4.4i):

RealOEM.com * BMW E53 X5 4.4i Cooling System Water Hoses

Here's a somwhat blurry picture of it from below:

Attachment 64986

I'm at the tail end of what's turned out to be a very large project to replace my valve cover gaskets and timing chain cover gaskets, which was complicated a thousandfold when I dropped the chain tensioner plunger into the lower timing chain cover, which necessitated removing everything from the front of the engine to retrieve it. I honestly don't remember disconnecting this hose - this I did disconnect I labeled to make sure I'd know where the go back, so this one has me baffled. I just don't see anyting in the vicinity of the end of this host that looks remotely like a hose fitting, and unfortunately the diagram on realoem.com doesn't show where it connects. I would be forever grateful to anyone who points out where this hose connects, as it's the last thing I have to do before topping up the coolant. Thanks.

Multi
My money would be on #2 in the link/diagram you provided......based on your pix....seems too large to be #3..........I could be wrong of course.......just my 2¢

C

It's definitely No. 3, based on the fact that the other end of it is connected into the fitting that hose No. 1 connects to at the top. The mystery hose is actually pretty small - maybe 1" in diameter.

I think I'm being thrown off by the fact that it's dangling down near the bottom of the radiator in my X5. I think it actually belongs somewhere higher up - it probably fell during the course of the project. I need to remove the covers to get a better look, but it's too late tonight, so I'll remove the covers when I get home from work tomorrow. It can't be that complicated - I'm sure it will stare me right in the face once I get access to it.

Multi
Hey.......missed the detail that you took the pix from below.......my bad......you are on track.....likely is #3.......best......C :thumbup:

Does it connect to the bottom of the water pump. There is a small diameter hose that connects to the pump just below where number 2 hose connects

Ah, now that's a distinct possibility. I will check there first, as I don't remember re-connecting a hose to the bottom of the water pump. I put the water pump back on fairly early in the re-assembly process, so it stands to reason that I forgot about connecting a hose to its underside, which isn't visible from the top. It was dumb of me not to label that hose. Thanks very much.

That was it. Thanks!