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