Vacuum leak - sound?
 

Still trying to track down my P0172 problem. I thought I smelled oil burning on my way home, so I when I got home tonight, I left the engine running and popped the hood. One good thing I noticed is that my new rubber oil cap seal looks to be working well. There wasn't any new oil dripping down the side where I put in oil.

One thing that I don't recall hearing before was a sound similar to a loud air leak. Imagine hearing air coming out of a flat tire. The sound was coming from somewhere be/w the PCV and throttle body, I think.

So, do vacuum leaks sound like leaks? My car just past 150k, and I haven't done a PCV replacement. I guess I was hoping to pass that joy onto the next owner ...

problem solved
 

not sure what line this is, but it was definitely needing to be replaced! I've never dealt with that type of clamp before. It was a PITA.

Sound near thermostat?
 

Is there a vacuum hose near the thermostat? I hear a faint sound that resembles an air leak.

Yes, vacuum leak do sound like that and the broken one is certainly a large vacuum leak.

Some have a vacuum nipple on the end of the intake manifold, down next to the power steering. The rubber elbow is common to crack.

Is this one easier to replace by removing the thermostat or to remove the fuel rail.

Fuel rail. If you're careful, you can pull the line up between the intake and engine block to replace the elbow. Just to break the hard plastic line.

I'm having PCV work done next week. I'll give them the elbow to put on while they've got the manifold out.