I know it is a prominent classic Mustang problem, so i'm sure more than one of you have been there before. Like so many others my ''66 coupe had cowl leaks that lead to rusted floors.
My dad and I are working on the floors now. We will soon be replacing the cowl vents and could use a little advice. Do you just have to cut it open, replace, and then weld it back shut?
Any hints/advice would be apreciated.

Thanks

 

jpony645 just redid his cowls, and did a fine writeup with pictures. He's the guy you want to see.

 

While there is no substitute for doing it properly (which involves drilling out ALOT of spot welds) there are various ways to go about it if you don't have the skills, tools, finances, whatever to do the job the hard and right way. That said, here is a quick band aid approach for you to have under consideration. For the record I would always choose to do things the right way and do them once, but fixed is fixed and better then broken no matter what we are talking about.

Top Hat repair with peep hole cuts to treat corrosion in the cowl.

a. Remove front end sheet metal, bumpers valances, hood, fenders, etc.

b. Remove heater and left air vent.

c. Nibble out the sides of the cowl grille that are UNDER the fender line. This will save you the cost of matching repaint. The holes in each side should be 6" wide x 2" high.

d. Clean all debris out of cowl and clean drains. Scrape and clean all the area of the cowl duct you can reach. You will have to use a coat hangar and improvise to get to the inside of the duct. After its as clean as you can get it, and after drying, treat with POR-15. Again you'll have to use a coat hangar wire with a daubber attached to the end to get round back of the duct. Once you have the area treated and its cured, put the nibbled metal back where it belongs and weld or braize the hole shut. Mask off prime and paint the spot any color (fender will cover it up).

e. Inside the car and under the dash treat the ducts with the adhesive coming with the cowl vent Top Hat kit and insert the Top Hats into the ducts. Use added weatherstrip adhesive or body Glazing and Bedding Compound (3M8509) if you need to to ensure a tight seal. Reinstall heater and left air vent.

Print this and take to a good body shop and ask what they want to do this... this will cost a fraction of what it will cost to replace the ducts. Top Hat kit...NPD part number 02228-1, $14.95, (800)874-7595

If you want the poor mans version of this, just do the Top Hat installation and forget about removing the front end sheet metal. and treating the top side of the ducts. A good Top Hat repair alone will last quite a few years. Treating the top side of the duct will make the repair permanent.


Here also is a link on the net for you to read up on.

http://www.***-internet.com/bjennings/cowlrepair.htm

 

Thanks for the info. The link was just what I needed.
My dad had a body shop for a number of years, so it we will definitly want to do it right.
Thats my car in my avatar. Hard to tell, but everything is stripped off. Fenders, hood, interior, engine. It will get a good sealing job and paint when everything is fixed. Hopefully soon as this will be my daily driver.

Thanks again for the help.

 

Isn't it something like 187 spotwelds to get the top of the cowl off? I agree with Pak-do it right, do it once.

While I had it apart, I'd paint everything that I could see with POR-15.

 

Mine had 130

Thanks for the props, Lman. Here is a link to the article I wrote up on my repair.

COWL REPAIR

 

Isn't it amazing how different these cars are--even ones built at the same plant in the same period? You have to guess that demand was so high, and the lines running so fast, that quality control was spotty, at best.

 

J--That's a good article! If I were you, I'd have left the signature in--What a cool idea!

 

I am going to put it back before I weld the top back down. I still haven't gotten that step finished.

 

Mine had 130

Thanks for the props, Lman. Here is a link to the article I wrote up on my repair.

COWL REPAIR
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I put your write up in the FAQ.