Cowl Panel Repair

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downwardspiral

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I got my car about 7 years ago, and ever since I had a problem with water leaking through the dash on the passenger side. It turned out my upper cowl panel was rotted out around the heater box inlet. This is apparently a very common problem on the older mustangs, so check yours out. I bought a welder a few weeks before starting this project, and never welded in my life prior to this. If you take your time and care enough to do a good job, this project honestly isn't too bad; even with no experience. Don't be afraid to do this! I am a 23 year old college student with no experience with body work/ welding and pulled it off!

edited to restore/add more pictures. I'll be 27 in May now :/ lol.

How to identify a rotted lower cowl:

vEsqg5E.jpg


In order to access the lower panel you have 2 major options: either remove the entire upper panel or cut a small piece of the upper panel to access your rusty area. I chose to remove the whole upper panel to make sure there was no other rust spots and to re-finish the entire lower panel with POR 15 to prevent future corrosion.

To remove the upper panel, the fenders, support brackets, wiper motor, arms and windshield will need to be removed.

mFnr3O2.jpg


My windshield was sand-blasted after 30 or so years of driving, so I didn't try too hard to get it out in 1 piece. This black snot is what holds the windshield in. A heat gun will loosen it up.

yeoYoDg.jpg


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In order to remove the panels which have been welded together, all of the spot welds must be drilled out. There are tools specifically for this called a spot weld drill (go figure), but be sure to buy a good one. I bought some cheapo ones from harbor freight which were useless to me, and ended up using a chisel drill bit anyway.

Support brackets removed, here's another reason to remove the whole panel:

pibBCIw.jpg


fT9N415.jpg


The hardest part of this step might be finding all of the 100+ spot welds. I used a wire brush on a drill to remove the seam sealer and rust that was hiding the spot welds.

Panel removed:

j1Y1u5E.jpg


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Wire brushing rust off (Respirator and mask is a must!):

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qtkQD9A.jpg


I then used little squares I cut from sheet metal to fill the holes from drilling. All I did was put a square behind the hole, then welded the hole shut. I grinded the welds flush and straightened out the panel.

Y5T8Upc.jpg


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Next, I cut the rotted section out and brought it to my local sheet metal guy. He made me a beautiful 3 piece assembly (nh) that made my life much easier.

7y0PiMV.jpg


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I shaped the panels with a ball-peen hammer. At this step, it is important to make sure the heater box lines up with the hole before the panel is welded in place. The undersides of the panels can be coated with weld-through primer for protection.

hQGljJO.jpg


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I cut around the panel so there isn't too much of a seam between the two panels where humidity can accumulate again.

DP2o9Bg.jpg


Tacked the panel in place. I started at the corners, going across the panel as far as possible between each weld. kind of like how you torque lug nuts in the star pattern.

PqftiAY.jpg


This was my first time welding sheet metal, so here are some vintage booger welds:

70PtT93.jpg


Then, I went batshit crazy with seam sealer and POR 15 to protect the panel from future rust. I didn't go crazy cleaning it up because it'll never be seen and I figured it would be better if I didn't remove any seam sealer.

QXr2hiT.jpg


Dk3x5MU.jpg


Next step was to line up the cowl panel, straighten it out, patch up some rust spots and paint it.

To patch the rust spots, I tack welded one side of the patch panel to the upper panel and used a hammer to shape it.

i2KQ1tR.jpg


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9gArWFS.jpg


Next step was to weld the upper panel back on (*make sure the arms for the wipers are in the right spot!*). I used about 5 clamps to keep the panels tight against each other. I also used 2 big bolts in the holes towards the outside of the panel. I tried to have 2 clamps close to the area I was welding the get it as solid as possible. Once it was welded on, It got more wire brushing, seam sealer and I hit the part where the windshield mounts against with a belt sander.

akSQjqw.jpg


Hm0d8SE.jpg


Then, the support brackets must be welded back on and the panel can be painted. I used more POR-15 and top coated it with semi-gloss spraypaint. Then all its needs is the windshield, wiper apparatus and fenders and your passenger has dry feet!

zG1bpXM.jpg


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RocketFoot

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Excellent write up! Thanks for adding it to the Wiki! The job looks great too! My cowl isn't too bad, but I need to rework the fender extensions on either side.

 

Don65Stang

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So easy, even a college kid can do it. Seriously, nice job & good for you at jumping right into it!

 
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Man That's great. Since mines already tore down to that point, I can remove it and go over it while the frame man has the car. Thanks! :goodpost:

 

kiko619

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why cant i see the pictures to the repair process. SOMEBODY HEEEEEELP I NEED THIS THREAD REVIVED :[

I'm a visual learner lol

 

OMS

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Now the replacement cowl is available

Item #3648KA

71-73 COWL PANEL, UPPER AND LOWER

***FREE SHIPPING*** Price: $424.95

 

kiko619

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Now the replacement cowl is available

Item #3648KA

71-73 COWL PANEL, UPPER AND LOWER

***FREE SHIPPING*** Price: $424.95
these cheeky bastards always want to charge up the freaking ass for the most basic thing.. i mean the hood of the car is more metal than anything. like i get it. its a lot of work to bend the metal to shape it the way its supposed to look. BUT COME ON!!! with prices like this its no wonder people just give up on the project.

 

OMS

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Now the replacement cowl is available

Item #3648KA

71-73 COWL PANEL, UPPER AND LOWER

***FREE SHIPPING*** Price: $424.95
these cheeky bastards always want to charge up the freaking ass for the most basic thing.. i mean the hood of the car is more metal than anything. like i get it. its a lot of work to bend the metal to shape it the way its supposed to look. BUT COME ON!!! with prices like this its no wonder people just give up on the project.
Really - before the cowl came out - used ones were 600 - 700 IF you could find one.

So how many hoods do you think will sell VS cowls - 20 : 1 - 50 : 1 Probably more ,so that means you could charge less for the part as you will sell a lot more. Wait till you see a door cost 650- there is not much metal there either.

 
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Now the replacement cowl is available

Item #3648KA

71-73 COWL PANEL, UPPER AND LOWER

***FREE SHIPPING*** Price: $424.95
these cheeky bastards always want to charge up the freaking ass for the most basic thing.. i mean the hood of the car is more metal than anything. like i get it. its a lot of work to bend the metal to shape it the way its supposed to look. BUT COME ON!!! with prices like this its no wonder people just give up on the project.
Really - before the cowl came out - used ones were 600 - 700 IF you could find one.

So how many hoods do you think will sell VS cowls - 20 : 1 - 50 : 1 Probably more ,so that means you could charge less for the part as you will sell a lot more. Wait till you see a door cost 650- there is not much metal there either.
Got to agree with OMS, having seen how much work it is to try and fabricate your own upper and lower cowls $450.00 is a bargain for quality ones already made to spec. It's like anything a business sells, the more they can sell of them the less they have to charge to recoup their investment and made a profit.

That's why the Air Force paid $7,600.00 coffee makers, they gave the builder specific build specs and only ordered a few of them. It didn't help that the specs called for the coffee makers to survive an airplane crash. LOL

 
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downwardspiral

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Pics are back up with a few extra ones. Sorry about that. Also regarding the replacement panels, I would have spent $500 in a second if those were available when I was doing the job. Price is based on supply and demand, it costs a certain amount to tool up a part. The more parts made from the mold or die, the cheaper the part can be sold for. If they sell 3 a year it's not profitable to sell it at $50 a set, and our cars are not popular. I am stoked to see any company supporting this body style.

 
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Mister 4x4

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Exactly right!

I know I would've gladly thrown the money at mine, rather than have to piece together the patches from the firewall of the car that I'd already cut away the front clip - 'yard dawgs went right through the vents on both sides, so I had to essentially weld both sides back together before I could fit them in - and I still suck at welding (essentially).

You also can't bash the vendors for the prices - the manufacturers set the price, and the vendors have to have a profit margin, otherwise they go out of business (they're not marketing and selling for their health, after all). When the product proves to be a solid money-maker for the manufacturer, the prices will come down.

 

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