Vacuum Lines and Air Box

Sparky · 09-15-1999, 01:50 AM

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 · 09-15-1999, 09:17 PM

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 · 04-02-2003, 08:45 PM

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 · 04-02-2003, 09:03 PM

Much appreciated.

04-02-2003, 08:45 PM	#3
JrseyKid86 Wannabe Elite Explorer Rochester Hills, MI 1991 Explorer XLT Join Date: Mar 2003 Posts: 17 Vehicle Specs	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. __________________ -Marc '91 XLT New Rockfordfosgate CD/MP3,6X9'' 250 Watt max output speakers, Alpine 4 channel amp, 2 channel Rockfordfosgate amp powering two 6X9 Explodes in the truck speaker box on either side of an 8" sub, interior rope and neon tube lights, custom fog lights, green LED backlit vents, customized stock grill, headlight strobes, bug sheild, custom pinstripes, custom window badging, aftermarket alarm, custom third brake light, drilled air box, DEE ZEE running boards... Customized interior painting, steering wheel cover, special 2 tone paint... and more

04-02-2003, 09:03 PM	#4
Sparky Wannabe Elite Explorer Join Date: Sep 1999 Posts: 2 Vehicle Specs (Original Poster)	Thanks guys... Much appreciated.

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
what are the 2 vacume lines on my 93 stock air box?	bnichols04	Under the Hood	12	07-25-2003 12:24 PM
Air Ride Shocks	JJCollett	Explorer - Ranger Shocks, Suspensions, Lift Kits	9	12-19-2002 05:33 PM

09-15-1999, 01:50 AM	#1
Sparky Wannabe Elite Explorer Join Date: Sep 1999 Posts: 2 Vehicle Specs (Original Poster)	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).]

09-15-1999, 09:17 PM	#2
Skip Pendle Wannabe Elite Explorer Vallejo, CA '93 Eddie Bauer Join Date: May 1999 Posts: 71 Vehicle Specs	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.