Mystery Hose - Where Does it Go?

Still trying to figure out the mystery hose my tech bud spotted a couple of days ago that seemed to be starting to crack from heat/age. To be more accurate, he reports the (1"-1 1/4") black rubber hose runs along the driver’s-side valve cover area until it reaches the area of the oil filler cap. Passing just below the cap it then makes a sharp downward turn and disappears out of sight. He tried to feel it as to where it went and what it connected to, but w/o success, although he opined it was very likely NOT a cooling system hose. Any idea what it is? :confused: btw, while he was feeling around down there, he discovered what he believes to be a smaller vacuum hose that was loose. If so, that might explain the constant, steady loud “whistle” sound we hear while the engine is running, along with the high (1,000-ish) idle RPMs. Does this sound possible, and, if so, which vacuum hose is it and what does it attach to? :confused:


most probably something to do with fuel evaporative charcoal canister system, but photos will help a ton.

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I agree that a picture will be needed here, the description is vague. The OP stated that the hose is 1" in diameter and I am not aware of anything in the EVAP system this large.

There is a breather tube in that location, but it should be quite obvious what it is and where it connects.