Can anyone give me advice on fixing the rust under my dash?
I have rust along the seam between the cowl and firewall.
I’d like to remove the cowl and do the job right the first time.
I realize the windshield has to come out and remove the countless
spotwelds. I’m planning on welding in new metal then treat with
Metal-Ready then paint with Zero-Rust.

I’ve never removed the windshield or any structural components such
as a cowl before. Are there any helpful hints anyone can give?

 

Some of the vintage Mustang forums will have extensive info concerning this area since the earlier stangs are notorious for rusting in the cowls. Different vehicle but comparable proceedures. Atleast it's Ford related. FoMoCo and Vintage Mustang are the most knowlegable about the subject. Also google search for "cowl rust repair". You should get a few thousand hits on that. Welding is a required skill for this repair. The rest is pretty straightforward, just a lot of time and sweat. Sorry for diverting you to other sites, but those Mustangers are experts on this subject. Good luck!

 

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Just finishing up a Mustang cowl. It's not a job for a beginner. The average quoted price is about $1500 and that is if everything (windshield, hood, fenders, & etc.) have been removed.

With the Mustang there are three different modes of attack. The first and easiest is to shove a 'hat' into the cowl/underdash opeing and glue it in. The next option is to cut openings in the top of the cowl. the last option is to drill out all the spot welds and remove the entire cowl.