Power steering hose, or reservoir leak?
 

I took the front cover off just now to do my coolant change and found that the hose on the left a little back from the radiator plug is covered in what I think is ATF (smells a little like it, black when I wiped it off with a shop towel).

Here's a photo

https://i.imgur.com/brxJWQA.png

I checked and hose at the top is also dark, so it may just be flowing down from there. The level in the reservoir is about at the bottom of the plastic indicator that's attached to the cap.

Is it likely the hose or the reservoir, or something else entirely?

EDIT: I haven't noticed any issues with steering, 04 4.4i

Thanks.

On the M54 the hose clamp, especially on the reservoir end, being loose is really common.

Good info, thanks. Is it usually a question of just tightening it, or is a replacement needed?

You probably don't have the right tool to tighten so just replace it with a gear clamp ;)

Perfect! I have a box of different sized gear-clamps. Thanks for your help.

Return hoses are notorious for leaks. I replaced the hose on mine. Worm gear clamps fixed leaks. Vibration and oil soak hoses causing them to leak. I try to remember to replaced the cap o ring every second oil change.

Thanks for sharing those tips.

I ordered some T-bolt clamps... set ranging from 3/4" to 2". I have some worm gear ones. My experience on my aluminum couplers for my two-inch flexible flat PVC irrigation hose is the traditional ones are less effective.

https://www.amazon.com/gp/product/B0DKF91PYH

Edit: it says the smallest one is 3/4", but the range in one of the pictures for that one says 28mm to 34mm... if it doesn't fit, I'll try a worm gear one

I'm not sure if this is true but I have heard that there's a little filter in that reservoir. And it's a good idea from time to time to replace that reservoir. I replaced it along with that hose, as it was leaking way worse than pictured here. Not too expensive. I figured leaks also allow dirt in and any dirt in the steering rack is not good.

I replaced the E36 rack with a reman one for about $400. The original one was leaking so bad. The e53 rack when I first checked it was like $1200. No dirt in the steering rack.

That's great info. I just checked again and there is ATF on the outside of the reservoir itself. That could be the o-ring on the cap is failing? Or maybe just the motion and vibration makes the fluid climb from the leaking hose?

I've had a recent weird experience with maple syrup in a dispenser where it climbs the walls and leaks out of the screw top, midway up the container... and no vibration or motion to speak of!

I looked at the clamp. It looks similar to the one for the CV boot clamps? I have this tool, though it's probably too big for my current problem:

https://www.amazon.com/gp/product/B0002SREPY

Is it best to remove the one bolt on the clamp around the reservoir to get access to the smaller clamps on the bottom or remove the bracket with the two bolts by the coolant expansion tank?

It's true that there is a filter in the reservoir and the whole thing is not that expensive. If you have oil coming out of the cap it is probably due to foaming. The expensive power steering oil is better for not foaming and quieter especially in the cold weather so if you are using ATF then you might want to change that.