Vacuum tree question.

[ArtReed]

On my 1993 Aero 4.0L 2wd xl, there is a "knurled" or spiral line that seems to go into the bottom of the vacuum tree. It goes around the back of the engine from driver to passenger side, and then I can't follow it. My question: is this a vacuum line? It seems to be loose when I move it up and down, but I'm afraid to pull it out for fear of breaking something. I hear a whistling sound coming from the engine, and am suffering from poor low speed idle. I replaced the vacuum modulator and that helped a lot. I am trying to find my erratic idle problem, which I suspect is a v-leak. Van runs great at higher rpm's.

 

[BrooklynBay]

Welcome to this forum! It sounds like the vacuum line going to the modulator is the pipe you're referring to.

 

[ArtReed]

Re: Vacuum tree question

No, I traced the pipe that comes from the trans/vac modulator. It is a solid pipe that comes up from below, turns toward the driver side, and is then connected by a short length of vac hose to the side of the vacuum tree. I expected this hose to be deteriorated, like the section at the trans., but it did not appear to be loose, or mushy.

The line I can't figure out is a flexible spiral hose/line that is attached to the bottom of the vacuum tree. It goes around the back of the engine, and then forward towards the front of the engine, on the passenger side. It seems to be loose at the vacuum tree. But, I'm not even convinced that it is a vacuum line.
It reminds me of a speedometer cable, or a brake cable on a bicycle.
Its connection on the bottom of the vac. tree seems loose to me.

 

[BrooklynBay]

Could you take a picture of it? Did you take a look at a vacuum diagram? It might be going into the evaporative canister or the cruise control.