Removing Vent Louvers & Sealing Cowl Areas.


A die grinder was used to cut out the louvers leaving one eighth inch of materials for our crimping/stepping tool. We made an edge all around the opening to provide support for the metal patch we will be installing later.

After cutting, we ground the edges carefully to smooth any sharp areas for safety since we will be putting our hands and arms into these openings to remove the debris that has accumulated over the years.

Although we didn't show it, you can see the edges are “stepped” and provide a ledge which will support the patch we are going to fit into the openings. We cut out a cardboard pattern, fit it, then cut metal.

The pattern is being cut out with scissors and we will fit it “precisely” before transferring it to the 16 gauge sheet metal and is then fitted again to insure we didn't miss anything. Before any patch is applied, cleaning is performed.

Test fitting the metal patch into the opening before we actually tack it into position and prepare for the welding operations. We tack on one end, then move to the other end for another tack and continue this process.

One side tacked into position and we will work on the other side around the wiper arm area. Notice the interior areas have been coated with Ospho for treatment of rust, then several coats of black paint.

The second area is being test fitted before we tack it into position. The center of the patch must be raised slightly to provide a smooth edge. Welding is performed in a hop scotch method and a quench cloth.

This area has been welded, ground, and is ready for a little body work and then the paint will be applied. Welding was a slow process since we “quenched” each weld afterwards to prevent warping.

This is a photo of a “finished” cowl vent seal area after painting. Looks factory doesn't it? We used photos of three different cars in this page since I couldn't locate all the photos that were taken. But you get the idea. No Louvers!

Cowl Sealing and associated Repairs

A common problem experienced by Maverick, Comet, and a large number of Mustang owners is a leaking cowl area which allows moisture to drain into the vehicle during inclement weather conditions.

This condition is caused in part by the rusting away of the interior metal pan areas directly beneath the cowl vents which in turn permits the water to drain “through” the damaged areas and onto your floor inside your vehicle. This also leads to the rapid deterioration of floor pans since the water does not evacuate and then the carpet usually holds the moisture and starts then promotes the rusting process.

One method of correcting this condition would be to drill all of the existing 100 or more plug welds out and remove the cowl so you can reach the inner areas and then either repair, or replace the entire section if you can find the proper metal pans to do so. Then re weld the new metal pan part back into the proper position and “Of Course” you would at this time administer a waterproof coating to insure this problem would not resurface again.

The method “we” chose to deal with this problem is shown in this article which depicts the removal of the louvered areas in the cowl entirely, welding metal inserts in and the subsequent repairs to the damaged areas with metal capping and fiberglass application layering over the damaged areas after treating with OSPHO.

Since we instituted and developed this procedure in 1997 (twelve years ago) we placed the information on our website to assist other Comet and Maverick owners in dealing with this problem. Some of those that have chosen to follow suit and seal the cowl vents on their own cars have given us a positive feedback. We have performed the process on six of our own personal cars with success in ALL cases and we are “updating” our page with more details and photos to further assist other Maverick & Comet owners in this procedure.

We here at CAMEO do not advocate that “you” as a car owner choose one way over another to correct this problem. We are merely going to show you how “WE” chose to correct this situation thereby giving you at least two options of dealing with the leaking cowl and the resultant damage.

The following photos show how we made repairs to the leaking cowl vent area on a 1975 Comet. The "louvered" areas were removed and sealed with metal patches previously. PLEASE NOTE # Although sealing the cowl as described "looks" great, it will not stop the water intrusion entirely. Its best to complete the "inner" work before sealing procedures.


We protect the edges with blue masking tape which may experience possible damage by scratching or nicking when fender is moved out of position. Blue masking tape is less prone to "lift" paint when removed and even then we remove the tape very slowly and deliberately.

We remove the grille from the front area and then the bolts which secure the outer fender to the "inner" fender are loosened and removed including those at the lower base .

Now we've removed the fender and placed it in a safe place along with the grille to prevent accidental damage while the other work is performed.

We first marked the area where we planned to cut into to inner firewall area with a die grinder cutting wheel.

You'll find there are two layers of metal you must cut through. Now we can see the damaged areas clearly.

Alex removes all the debris from the areas under the cowl then wire brushes surface to remove any rust, scale or loose pieces.

A close inspection reveals a badly damaged area which must be welded before sealing can proceed.

Grinding all edges will prevent any cuts to hands and arms when working the inner areas during sealing operations.

A vacuum cleaner removes all the loose dust and particles that might interfere with the glassing process.

A close inspection with a flashlight will tell the extent of the rust damage to the sections under the cowl area. So far just the ends show deterioration.

This is all that's left of the chimney on this side .The large hole created by its absence will be patched before we can proceed with the sealing process.

The “Vintage” AC unit and its bracket can clearly be seen through the hole. Can you imagine how much water was able to penetrate this area if not sealed?

The 22 gauge patch has been cut with rounded corners to ease its installation when positioning the piece prior to the welding procedures. The Drivers side will likely need the same procedures as is shown here on the passenger side.

Alex carefully moves the patch into the correct position from the “inside” of the car and makes sure all open areas are completely covered before welding procedures are commenced to secure the plate in its final position.

Now we're ready to weld the patch plate into place. Welding will be performed at only strategic places to secure the patch and then the fiber glassing procedures will then cover all the surfaces shown for a thorough sealing of these areas.

Grinding the metal to find a clean area will greatly aid the welding process so a little more cleaning is in order.

Caution is necessary when welding or grinding and protective pads were on the floors “inside” the car just in case.

Welding in several locations, Pressure was applied from under the patch “upwards” to make a tight seal.

Welding is a sure way to speed up the patching process but patches can also be secured by sheet metal screws.

Six welds as shown are sufficient to hold our patch in place. Now we can begin our resin application process.

After resin hardens this product turns a dark brown color and makes a complete bond to the metal surrounding it. Now we close it up.

Dr. Bill tacked the original pieces back into position and then welded them securely to the surrounding areas to make a complete seal. Prior to welding, we spray painted the entire work area and all our welds to protect from rusting conditions. We then checked inside and outside all areas to make sure there were no FIRES which may have been started by our work procedures. We have fire extinguishers and a water hose very nearby in the event this could happen. No fires or smoke so we prepare to button up the passenger side and move on to the driver side where we will repeat the process again. We do one side at a time since we've found that is best not to get too “spread out” when doing this work. This way we don't have to rush.

A generous application of a good quality black paint to all the areas under the fender area and we will proceed to put the fender back on this side.

The masking tape can now be removed very c a r e f u l l y … sometimes the paint could come off with it if you are in a hurry. We take our time here.

Alex aligns all the fasteners and then “starts” them before finally tightening any. He will align the fender to the body area FIRST then tighten.