 Our cowl is shown here properly...  Our cowl is shown here properly repaired and basking in a coat of POR-15 rust-preventive paint. Using POR-15 is a sure way to prevent ever having to replace the cowl again. |
Cowl vent leaks are the Mustang owners worst nightmare. Just about any vintage Mustang in need of restoration is going to need some sort of cowl panel restoration. Some cowls have minor leaks and can be patched, others need complete replacement panels (and we can thank the reproduction metal companies for making this step much easier), and the worst of them need complete replacement cowls.
There is very little in the way of diagnosissimply run some water into the cowl vent and see where it leaks from. On the worst cars, you can also see rust damage from under the dashwith the heater case and the driver-side fresh air vent removed. Its pretty much a given that the cowl will leak when you test it in this manner. The only things left to do is remove the top of the cowl area and survey the damage.
But why is the Mustang cowl design so prone to rust perforation? Well, its a simple fact that the cowl of the early Mustang was poorly designed. The cowl, as it was welded together, had no access for proper paint application or rust inhibitors. Back then, metal wasnt dipped in EDP primer as it is commonly done now on modern cars; the protection came strictly from paint application after the body was assembled.
The drainage of the cowl was poor, and any large items, such as leaves, twigs, and paper, could easily slip past the large cowl vent slots and dam up the drain areascausing standing water to sit around the unprotected metal top hats of the cowl vent areas. Though the design changed for the 69 model, its interesting to note that Ford used a similar design for the Fox-body Mustang from 1979-93a large cowl vent opening with a single air inlet on the passenger side. The drainage was improved, but the vent slots were plastic and smaller (allowing for paint application inside the cowl before the vent was attached), and the metal was EDP-coated as well.
Project 66 needed cowls, of course, as do most 65-68 northern cars. We didnt know what we would findand except for looking under the dash (the interior was gutted for paint and body work), we didnt see any major rust perforation. We hoped cowl patch panels would complete our job efficiently. To be prepared, we ordered a left and a right cowl patch panel from The Paddock and sent them over to Classic Creations of Central Florida, so that when we arrived to shoot this article, they would be ready for assembly. Take a look.