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Old Aug 5, 2013 | 04:19 PM
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I found this line,, it comes out of the fire wall and was ran over to the passenger side fender and ran under it .. The end wasn't connected to anything.. Any ideas what it is and where it should be connected?? Thanks


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Old Aug 5, 2013 | 04:30 PM
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I have a line like that on my 81. Its a vacuum line and goes to the back of my carb. Not sure if yours is the same.
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Old Aug 5, 2013 | 04:53 PM
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Thanks for the fast reply,, I will take a look and see .. The line is pretty long, when I found it the end withe the small hose was ran along side of the right fender and was almost to the radiator..
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Old Aug 5, 2013 | 05:20 PM
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Is it this?
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Old Aug 5, 2013 | 05:36 PM
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It looks the same, mine has a small piece of hose clamped on it.. What is yours connected to?
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Old Aug 5, 2013 | 05:49 PM
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That looks like the coolant bypass module for the heater.
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Old Aug 5, 2013 | 06:04 PM
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Thats what it is,, it looks like mine has been replaced at some point and the old line that I found was left in there ... i guess it wouldn't hurt anything to cut the old one off back close to the firewall...
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Old Aug 5, 2013 | 06:13 PM
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I would make sure that line isn't seeing vacuum at any point so you aren't leaving a vacuum leak.
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Old Aug 5, 2013 | 06:34 PM
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Originally Posted by Amorget
I would make sure that line isn't seeing vacuum at any point so you aren't leaving a vacuum leak.
i checked and there is no vacuum,, does the line on your car go through the firewall ?
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Old Aug 5, 2013 | 08:31 PM
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So you're saying there's a line attached to the heater hose shutoff already??? If so, the line you're showing may connect to the larger rubber vacuum hoses near the firewall by the brake booster. That may be the line not coming OUT of the firewall but going IN. To control your AC stuff. See that clump of hoses to the right in the pic..................

And mine has, from the factory, a small rubber hose with a "loop" that goes around the fitting to help keep the line connected to the valve fitting.

Last edited by KapsSA; Aug 5, 2013 at 09:04 PM.
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Old Aug 5, 2013 | 09:06 PM
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Originally Posted by KapsSA
So you're saying there's a line attached to the heater hose shutoff already??? If so, the line you're showing may connect to the larger rubber vacuum hoses near the firewall by the brake booster. That may be the line not coming OUT of the firewall but going IN. To control your AC stuff. See that clump of hoses to the right in the pic..................
Mine has, from the factory, a small rubber hose with a "loop" that goes around the fitting to help keep the line connected to the valve fitting.
The line that is connected to the coolant bypass module for the heater is connected to something over in the area that you are talking about .. Not sure if thats where it is supposed to be connected but thats the way it was when I got it..
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Old Aug 5, 2013 | 09:13 PM
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The line from the heater hose shutoff valve should go through the firewall more on the passenger side and it connects to a vacuum shutoff valve on top of the heater box. Going direct to those large hoses by the booster would make it always shut.
Pull the glovebox out and you'll see the vac switch. There's a cable going to that switch controlled by the Hot-Cold lever
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Old Aug 5, 2013 | 09:16 PM
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KapsSA,in you picture on the carb between the accelerator cable and the throttle spring there is some linkage,, can you tell me what it is / I dont think that is in mine.. Rochester Quadrajet
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Old Aug 5, 2013 | 09:16 PM
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Also, if you determine where the vac lines are going through the firewall, you'll find that the rubber grommet is also a multiline connector on the back side.
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Old Aug 5, 2013 | 09:18 PM
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Originally Posted by 1978vett
KapsSA,in you picture on the carb between the accelerator cable and the throttle spring there is some linkage,, can you tell me what it is / I dont think that is in mine.. Rochester Quadrajet
The cruise control stuff?
Is yours a 4 speed?
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Old Aug 5, 2013 | 09:45 PM
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No its a auto.. ,,, sorry to change subject so quick.. I think my heater control valve line is the one that I found thas is diconnected, and the other line was used to have it off all the time,, I dont no why someone would do that..

Last edited by 1978vett; Aug 5, 2013 at 10:13 PM.
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