4.2L vacuum line diagram?

David11946

Original poster
Member
Apr 24, 2012
14
New York
Iv'e been looking around for a vacuum line diagram for a 4.2L I6 and I can't seem to find one. Can someone let me know where to find one? I bought my TB used and I thought they came from the factory with a sticker somewhere under the hood (like the old models). My TB doesn't have it and I haven't seen one in the Haynes manual.

I have an open vacuum port on the intake manifold plastic cover at the front. It is in the same side as the air resonator. I only just noticed it while I was changing plugs and coils today. Would anyone know where that port is to be connected ( or the diagram would be great)?

Thanks for the info if you have it.
 

Mypetropig

Member
Dec 29, 2011
226
You need to fill out your profile info so that we know what model year you have when we look at the thread. If yours is before 07, I think that's the year the went to the MAP sensor by the air cleaner, then you have two lines for vacuum off the resonator. One of the lines comes off the valve cover and attaches to the lower left of the resonator. Its for the crank case vent and is about a 1/2" in diameter. If its on the upper right then thats the fuel pressure regulator and is about 1/8" in diameter. Hope this helps.
 

limequat

Member
Dec 8, 2011
520
lol there's no vacuum line diagram because there's a sum total of about 3 lines. There's the big ones that go to the booster and evac, and one little one for the fuel pressure regulator. Think that's it. Show us a pic.
 
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jalmanza

Member
Feb 2, 2021
1
home
Iv'e been looking around for a vacuum line diagram for a 4.2L I6 and I can't seem to find one. Can someone let me know where to find one? I bought my TB used and I thought they came from the factory with a sticker somewhere under the hood (like the old models). My TB doesn't have it and I haven't seen one in the Haynes manual.

I have an open vacuum port on the intake manifold plastic cover at the front. It is in the same side as the air resonator. I only just noticed it while I was changing plugs and coils today. Would anyone know where that port is to be connected ( or the diagram would be great)?

Thanks for the info if you have it.
did ou ever find out where the vacuum lines attach?
.
 

Mooseman

Moderator
Dec 4, 2011
25,307
Ottawa, ON
If you're talking about that nipple on the driver side of the resonator, it connects to the fuel pressure regulator as per this image:

100_4647-jpg.52893



Or do you mean the one on the intake?

wp_20130810_003-jpg.51169


That one connects to the vacuum line that goes to the rear heater coolant diverter valve on EXT's only. SWB trucks are plugged with nothing connected. Seeing yours in an EXT, you should have it. It's a plastic line that runs from the back to the front of the valve cover.

 

mrrsm

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Oct 22, 2015
7,679
Tampa Bay Area
Dec 5, 2011
576
Central Pennsylvania
So this Vacuum Port on the intake manifold should be capped on my 02 LS?
It is most likely that the port you are referring to goes nowhere. It is likely plugged on the inside - if it weren't it would emit a sucking noise constantly. If you put your finger to it and feel vacuum, then YES you need to plug it. My '02 Bravada had a rubber cap on the end of this and it disintegrated over the years. It is plugged on the inside but I placed a new cap on it anyway.
 

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