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Firewall Hole Condundrum

4.3K views 21 replies 13 participants last post by  68'Stang  
#1 ·
Hello Stanger's

I have an issue.

My car did not come from the factory with a/c. A previous owner has installed a/c and has moved the hoses from near the center of the vehicle to the passenger side.

Problem is that there are two holes where the hoses used to be (see picture).



I ordered the fire wall grommets however because there is a lip on the engine side of the holes they will not fit. :shrug:

What I want to do is go in there with my dremel with the flex hose attachment and cut the lips off however I may win the 2016 Darwin Award for burning the house down. :lol::lol:

If any body has any thoughts on how to solve this problem could you please post it as it is a tad breezy in the car.

Thanks

Tom
 
#2 ·
Can you get some of those press in metal caps, I don't know what they are called but they're just a disc with tangs on one side so they just snap in. Usually in the 'hardware' section of the hardware store. Can also find plastic ones. In various sizes.
 
#9 · (Edited)
Perhaps Im misunderstanding you but the holes you show are the factory holes for the heater hoses for non-AC cars. The 'lip' on them is really a rolled edge to prevent chafing of the heater hoses. Looks like someone tried to put silicone RTV, etc, on those.

Those holes check almost exactly 1 inch diameter. My car:
Image


The rolled edges protrude about .230 on the inboard side and about .120 on the outboard (R) side allowing the holes to 'point' more toward the outboard side (away from the engine):
Image


Im not sure what plugs you are trying to use but these are the proper ones although I can see how the protruting edges might interfere with proper seating as the plug is made to 'grip' only about the basic sheet metal thickness:
Scott Drake 377678-S2 Mustang Firewall Heater Hose Plug 67-68

Good luck
Paul
 

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#10 ·
This is exactly what I am trying to explain. All of the hoses now run through the large hole on the passenger side of the firewall and I am trying to plug the two original heater hose holes.

Those are the heater hose plugs that I ordered by like you say, they will not fix because of the protruding edges.

That was me that used an adhesive with a different type of plug but they did not work. I just have not had a chance to clean it off yet.

Thanks for helping me explain.

Tom
 
#15 ·
Fit the plugs from inside, not the engine bay, like the factory did. If the softer rubber, not the rock hard some repros use, they should grip...
 
#17 ·
Hmmm, that could work. Cut, weld, grind, bondo, sand, paint...


But that seems slightly harder (and maybe more expensive) than installing the two plugs FoMoCo used on the line to block them on all factory A/C cars...


Not sure why folks like making simple things so hard/complex... :smile2:
 
#18 ·
I tried a couple of different things on my 67 and didn't like the looks of any of them. Ended up using a hole saw to cut the offending holes completely out and made round plugs from spare sheetmetal. Welded it all in, ground/sanded it all smooth and now it looks as if they were never there. But boy what a pain. The holesaw cuts too much of a gap so you can't use the same one to cut your replacement plugs. You have to use a bigger one and slowly grind the diameter down to fit. Wearing REALLY thick gloves so the plugs don't amputate fingers while trying to escape the grinder. Then you are welding a small area so you can only tack a little, let it cool a bit, come back for a couple more, etc. And in the meantime the plugs are doing their best to wiggle out of the holes and refuse to lay flat like anyone would expect. OK, and I set minor fire to the interior of my car a bit like twice during the welding. No harm done at all but it was extremely unnerving. Then when the welding was done and ground smooth I shone a light from the interior that showed me that I was NOT freaking done. That happened a couple times more until I was about sick of the whole thing but I was determined not to leave any pinholes. Then finally I was able to bondo and spay primer. I wouldn't consider any of this with the engine still in.
Just saying. Instead saying "Oh the only proper way is to weld in metal plugs, nothing else will do." About halfway through the job some of those rubber or steel press in plug solutions started looking pretty darn good I can tell you. No one was more surprised than me that what I thought would be a fairly straightforward hole-filling job turned into such an ordeal. With a little sealant and a helper inside the car I bet you could put a couple of those plugs bartl showed us in in like five minutes flat.
 
#22 ·
Thanks for all the great ideas everybody. I do have the FoMoCo plugs and I will try installing them from inside. I had a quick look under the dash today and it looks pretty tight under there so I think there will have to be some disassembling going on in order to do that. Failing that I will likely go with bartl's idea.

I figure I have at least 4 months until I can take the car out here on the streets in Calgary so I have plenty of time to figure it out.