Vacuum Lines and Air Box

[Sparky]

Gentlemen,
I have a 91 Explorer, 4.0L, 4WD and have a few questions about the vacuum lines at the rear, top of the air box. One has a yellow stripe on it, and runs down underneath the intake, and the other is routed over/behind the engine, connected to a vacuum port, on the upper intake manifold. The one connected to the vacuum port is attached to the left side of the box, closest to the fuse box. I'm just wondering: Is this hooked up correctly? Also, does it matter which side of the bi-metal switch the two lines are connected to? Lastly, just what does this setup do..??

Thanks!
Robert

[This message has been edited by Sparky (edited 09-15-1999).]

 

[Skip Pendle]

This set-up is there to pre-heat the intake air for quicker warm-up and to de-ice the intake manifold during sub-freezing weather. The line going below the air box is connected to a diverter valve in the air intake that mixes outside cold air and hot air that comes from an "oven" attached to the righthand exhaust manifold. You can check if this valve is working by gently sucking in and releasing on the line, you will hear the valve moving back and forth.

Frankly, I don't know what would happen if you reverse the two lines at the air thermostat on the air box.

 

[JrseyKid86]

i took my lines off of my 91. rougher idle. The line that sucks air has to be on the left hand side when your looking at the front of the car. The one on the right, that looks like a shoelace doesnt really serve a purpose to my knowledge. But the one on the left sucks air from the airbox... kinda stupid if you ask me. But i dont know what its there for. No problem running w/o the lines in 65 degree Michigan weather.

 

[Sparky]

Thanks guys...

Much appreciated.