Help. Rusted cabin air intake, no "cover" to remove?

[scartail]

Hey all, so the intake under the cowl has rusted thru. Rain leaks into the passenger side. From my search, to access the intake, I am to remove the "cover", which is spot welded on. The problem is I found no spot welds and can't feel the lap joint.Do I cut it out anyway? I've sanded around looking.

Any help? 77 coupe. .

[AydinZ71]

In my humble opinion, don't bother removing the top of the cowl to access that rust. Removing spot welds is a tedious process with a panel that big. You should just cut out the piece that is rusted from inside the cab. You have to remove your dash and accessories near the rusted location. You would need to do this anyways if you were to cut it our from above. You will not want to burn these surfaces when you weld-in a new panel. You can fill it with Por-15 (as an alternative), both the paint and the seam sealer, but it will still be a temporary solution. Metal that has rusted completely through will become more and more brittle over time, even if it is incapsulated. 

[malus_rex]

On 77-78s the cowl cover is one piece and you cannot remove the top easily. I agree with Aydin, your best bet is to go from beneath and weld a new panel into the bottom. I have a '76 and I was able to remove the top, but I ended up welding from the bottom anyways because it's very tight coming from the top.

[scartail]

thanks for the tips guys. i wanted to confirm that the "cover" wasn't there for my model.

[scartail]

On 4/3/2022 at 12:26 AM, malus_rex said:

On 77-78s the cowl cover is one piece and you cannot remove the top easily. I agree with Aydin, your best bet is to go from beneath and weld a new panel into the bottom. I have a '76 and I was able to remove the top, but I ended up welding from the bottom anyways because it's very tight coming from the top.

hey malus_rex, do you have any pix of the panel you made to weld in from under? the rot on my car looks to be just on the stack/chimney portion. thanks in advance.

[seattlejester]

Spot welds need to be drilled out, a lot more effort than it is really worth.

 

VFib did it on his car, I think we found a 4x3? and that was pretty close to the dimensions to replace his rusted out piece. If you do remove it, totally worth cleaning up the area and seam sealing the seams

[AydinZ71]

I didn’t bother with the spot welds. I just removed the lap joints in their entirety and did full-seam butt-welds throughout. Once the epoxy primer was on, I had no need for seam sealer since I no longer had any exposed lap joints. The downside is you need to have good practice with butt welds, need to be more careful with managing heat, it’s not OEM (not that anyone will notice). I have done it both ways now, and prefer the butt-welds. Once the epoxy primer is on, you can easily spot gaps and holes in your weld work, and top-dress with a single-component epoxy seam sealer 

Edited May 16, 2022 by AydinZ71

[scartail]

On 5/16/2022 at 4:31 PM, seattlejester said:

Spot welds need to be drilled out, a lot more effort than it is really worth.

 

VFib did it on his car, I think we found a 4x3? and that was pretty close to the dimensions to replace his rusted out piece. If you do remove it, totally worth cleaning up the area and seam sealing the seams

 

On 5/16/2022 at 5:57 PM, AydinZ71 said:

I didn’t bother with the spot welds. I just removed the lap joints in their entirety and did full-seam butt-welds throughout. Once the epoxy primer was on, I had no need for seam sealer since I no longer had any exposed lap joints. The downside is you need to have good practice with butt welds, need to be more careful with managing heat, it’s not OEM (not that anyone will notice). I have done it both ways now, and prefer the butt-welds. Once the epoxy primer is on, you can easily spot gaps and holes in your weld work, and top-dress with a single-component epoxy seam sealer 

thanks for the replies. i'm heading torward butt-welding it in. I'll remake the chimney, and put a flange, like a top hat. i think that would be the easiest for me to weld from underneath. the firewall is in good shape, so i don't want to mess with it.