Loose Tube...?
 

Hey I was messing around under the hood today just checking spark plugs and all that good stuff when I found a loose what I am assuming is vacuum tube. I don't have a manual yet so I have no clue on figuring it out. I have picture below, I doubt it's for drainage of any sort, but your help is much appreciated. BTW this is a 1986 Mercedes 300E W124

The tube was originally hanging down towards the ground towards the engine.

That vac line should be attached to the intake manifold near to the #1 intake runner. I'd guess that you have a nipple on the intake with nothing attached to it.

Just out of curiosity the absence of this connection can have what results?

I discovered the same thing on my car--the vacuum tube coming off the ELZ AKR and going to nowhere at the back of the engine. It must have been like that for years. After I discovered it, I suspected it should have been connected to the intake manifold, somewhere, but I couldn't find any nipple that was uncovered, so I tapped into an existing vacuum line with a T-fitting. Honestly, it didn't seem to make a difference one way or the other.