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Discussion Starter #1
Got some pics of a truck I am considering to buy, but noticed that there seems to be a hole in the firewall that is not stock...see pic.

What might have been done there? wires for gauges?

:help:
 

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Probably wire for a chip ang guages. Could have been neater, but looks like they took the direct route.
Looks like some spray foam is in order.
 

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Might have had some gueges in side the truck, and used the hole to run the wires to the engine.
 

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Surely you don't need a hole that big for gauge wires. I might guess a 4ga or larger power wire for an amp. Although I didn't drill a hole in my firewall for one, never mind just thinking out loud.
Rick.
 

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coulda been a CB antenna cable. big connector, you know.
 

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That hole is huge. If i was you i would just ask him what that was used for, and see what he says.
 

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Is that what the finger stick is used to fix.):h HA HA I just couldn't resist. Who ever did that either had no idea what they were doing. I wouldn't really worry unless you can find something physically damaged. There are a lot of d maxes that are sold everyday that have had huge HP put to them with no physical evidence of it. So at least you know that something was done
 

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If you look at the picture, it appears that there is an indented stamping in that sheet metal. If I had to guess, there was once that aluminum foil/heat pad material behind there. Perhaps it is an opening designed for certain trucks and not others? It looks like the place where I ran my EGT and boost leads thru....ALMOST, except I had that aluminum heat shield matting pad there...I just cut thru it with a boxcutter....hmm...not certain...Just ask...

Mike
 

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Check the waste gate line, also check the passenger side manifold for a plug. Might have had a tuner on it, gauges or other misc things.. Best bet would be gauges. Also did the bed have a hitch in it?
 

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The diesels are much more sealed up at the firewall than the gassers. I finally gave up and routed my wiring under the floor pan on the drivers side and through the (? speedo cable?) rubber grommet. That hole looks like a wiring cobble job. Look and see if he just removed a factory sealed grommet or drilled his own hole (if so, what else got drilled; if nothing, you have a place for your wires!).
 

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Better plug that up. Otherwise, you won't ever need any heat from the HVAC system!
 

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Do a search on firewall routing, guys!;) That is the standard and preferred location that most gadget/power guys drill a 1 to 1 1/2 " hole to route stuff through. That might include gauge wires, chip wires, boost sensor hose, and many other things (maybe even a long flexible tube to the hidden insulated beer tank under the truck?) :eek: .

Might be harmless, or he may have really abused it, but that alone shouldn't discourage you from buying it. Ask about it. He may have just saved you a little effort for when YOU start adding things! :D

That is the preferred location because it is a bare metal circular location inside and out. If I'm not mistaken, it is the routing location when the snow-plow prep package is ordered.

Most guys drill it out big, 1" plus, or later wish they had. This is so it can be used for additional routings in the future. Any excess space can always be sealed until needed by stuffing with cotton or use of spray foam.

One word of caution, it should have a rubber grommet put on it (I used a pcv grommet on mine) or make sure any wires you run through it have a length of looming around them. ):h
 

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Discussion Starter #14
Thanks for all the input, I decided against buying this truck !
Will go for a different one.
 

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Do a search on firewall routing, guys!;) That is the standard and preferred location that most gadget/power guys drill a 1 to 1 1/2 " hole to route stuff through. That might include gauge wires, chip wires, boost sensor hose, and many other things (maybe even a long flexible tube to the hidden insulated beer tank under the truck?) :eek: .

Might be harmless, or he may have really abused it, but that alone shouldn't discourage you from buying it. Ask about it. He may have just saved you a little effort for when YOU start adding things! :D

That is the preferred location because it is a bare metal circular location inside and out. If I'm not mistaken, it is the routing location when the snow-plow prep package is ordered.

Most guys drill it out big, 1" plus, or later wish they had. This is so it can be used for additional routings in the future. Any excess space can always be sealed until needed by stuffing with cotton or use of spray foam.

One word of caution, it should have a rubber grommet put on it (I used a pcv grommet on mine) or make sure any wires you run through it have a length of looming around them. ):h
:exactly:

I drilled mine out huge and then put a adjustable grommet in it, so the hole can effectively grow as I run more things through... right now I just have boost / egt lines
 

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I finally gave up and routed my wiring under the floor pan on the drivers side and through the (? speedo cable?) rubber grommet.
):h Speedo cable??? :lol: GM hasn't used a speedo cable since the late '80s to early '90s, it's all elecrtic now. That cable is the trans. shift cable.
 

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Thanks for all the input, I decided against buying this truck !
Will go for a different one.
If it was a 4x4 I would say that hole was for the snow plow harness, that is where mine is!!
 

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Might be where they ran the lines for air bags. That's where I ran mine through. It took a pretty big hole to get all the lines and wires through for the gauges and compressor.
 

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Do a search on firewall routing, guys!;) That is the standard and preferred location that most gadget/power guys drill a 1 to 1 1/2 " hole to route stuff through. That might include gauge wires, chip wires, boost sensor hose, and many other things (maybe even a long flexible tube to the hidden insulated beer tank under the truck?) :eek: .

Might be harmless, or he may have really abused it, but that alone shouldn't discourage you from buying it. Ask about it. He may have just saved you a little effort for when YOU start adding things! :D

That is the preferred location because it is a bare metal circular location inside and out. If I'm not mistaken, it is the routing location when the snow-plow prep package is ordered.

Most guys drill it out big, 1" plus, or later wish they had. This is so it can be used for additional routings in the future. Any excess space can always be sealed until needed by stuffing with cotton or use of spray foam.

One word of caution, it should have a rubber grommet put on it (I used a pcv grommet on mine) or make sure any wires you run through it have a length of looming around them. ):h



:exactly:


Thats where the factory drills the hole for the snow plow prep package to route the wires thru.

It's easy to drill from the engine side and theres a corresponding clear are behind it in the cab.

I also drilled mine out to one and a half inches to allow for running more wires as the add ons build up, it's about 1/2 full now :eek:

Just dont forget to put some sliced rubber hose around it to keep from chafing any wires later.

.
 

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Discussion Starter #20
It is a 4x4 and used to be in Flint, MI .... would be very possible !


If it was a 4x4 I would say that hole was for the snow plow harness, that is where mine is!!
 
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