Scuttle Vent & Drain Repair and Modifications

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After removing the gauges, dashboard and steering column, it was time to clean and prime the scuttle vent and dash areas. I knew immediately why the floor pan was rusted as soon as I saw the area around the driver's side scuttle vent drain (left picture). Rust holes in the scuttle vent were allowing water to drain into the footwell (I always thought the seals around the convertible top were bad!!!). A quick look at the passenger side revealed the same problem (right picture) although it was not as severe. After looking at the rust holes, it was obvious that the scuttle vent was rusting from the inside. Any patches applied to the outside of the scuttle vent wouldn't last as the scuttle vent would continue to rust thereby creating additional (and larger) holes. The only way to fix this is to replace the rusted metal with new metal and use chemical products to convert any remaining rust into a stable form.

One option was to replace the entire scuttle vent with a new piece, so I set out to determine how much work would be involved. I examined all of the seams and realized that to remove and install a new vent in a factory-like manner, I would have to remove several other panels. After some thought, I decided to forego replacing the scuttle vent and decided to fix the existing vent with patch panels.

After marking the scuttle vent for the patch panel, I used an air-powered cutoff tool to make an opening. I found about a 1 inch deep layer of rust, dirt, leaves and pine needles in the bottom of the vent cavity. Poking a wire up through the drain hole dislodged more rust, dirt and leaves confirming my suspicions that the vent was draining very slowly if at all. A small wire brush and a shop-vac soon took care of all the crud. Sorry for the image being fuzzy - this happens when I get the camera too close to the subject. I think you can see the crud at the bottom along with the rust and holes in the firewall. The firewall provides a portion of the scuttle vent cavity.

I thought I took pictures of the next steps but I cannot find them. I will give a written description of the work and will take photographs when I start on the passenger side. The original opening I cut was not large enough for me to easily clean and repair holes in the scuttle vent. I cut a second opening and saved the cutout piece of metal to close the opening upon completion. After cleaning out the cavity with a shop-vac, I used a small wire brush, old screwdriver and other tools to remove as much of the rust scale as possible. I used a product call OSPHO to convert the rust into a stable form. After it dried I used an epoxy paste called PC-7 to repair the smaller holes in the scuttle vent and on the firewall. For the larger holes I used JB weld (epoxy glue) and fiberglass mat just like you would for a fiberglass repair. I painted the entire inner cavity with two coats of Corroless (an Eastwood product) after the epoxy cured. I sprayed the patch panel with a zinc-based welding primer and used about six or seven tack welds to hold it in place. I used only a few tack welds because I was concerned with overheating, and thereby ruining, the epoxy if I tried to weld the entire patch panel seam. Also, some of the metal was too thin and quickly burned through. I am not concerned with the appearance of this particular repair because the repair will be hidden by the dash and I will not have concours judges looking over the car. I am concerned with rust prevention, water tightness, and keeping my feet dry when it rains.

After tack welding the panel in place, I used epoxy and fiberglass mat to seal the open seams on the patch panel. This picture shows the repair before I painted it with Corroless (the silvery gray areas are wirebrushed metal and epoxy glue).

- More to come about this repair -

Continue reading for another Modification to
keep water from draining into the fender cavity.

If you have read the other repair related pages on my site, you have realized that my car had several rusted areas requiring extensive repairs. One of my goals while doing repairs is to identify why the area rusted and what I can do to prevent it from happening again. It appears as if the original designers of the TR-6 allowed water to drain into the fender cavity and onto other body panels rather than drain it directly away from the car. The scuttle vent is the primary source of water being drained into the fender cavity. Another source - although it doesn't drain directly into the cavity - is the channel where the rear of the engine hood (or bonnet) fits (the image to the left shows what I mean by the channel). The water entering the channel drains toward the fenders and either drains through the engine compartment or makes its way into the the fender cavity.

I wanted to make modifications to drain this water in such a way that it would NOT go into the fender cavity or over other panels. I decided to create something similar to a sink drain located at the end of the channel. I used copper tubing to form a water duct and will block the end of the channel to force the water into this duct. I will connect to water duct to the scuttle vent drain tube and have all of the water from the scuttle vent and this duct drain out underneath the vehicle. Look at my page on the repair work to the rocker panels and you will see where the scuttle vent drain tube will pass through the rocker panels so the water drains out directly underneath the vehicle.

Based on the size of the channel, capacity to drain water quickly, ease of cleaning in case of clogs, and what I had on hand, I used 1/2" copper pipe and fittings to fabricate the duct. I started by drilling an oversized 1/2" hole at the very end of the channel. I then took a short piece (about 1 inch) of pipe and put a very small flare on one end. (The image to the left shows the entire duct - You may be able to see the small flare at the top of the pipe.) This provided a mechanical stop that holds the pipe in place and keeps the top flush with the channel when I insert it into the hole I drilled in the channel. I put the pipe into the hole and fitted a 1/2" copper elbow on the end protruding into the engine compartment. To locate where I needed to drill a hole in the fender wall, I rotated the copper fitting until it touched the fender wall.(The image to the right shows the fitting touching the fender wall) I placed a small punch inside the engine compartment next to the fitting and centered the punch to the center of the fitting. I made a small dimple which I could see from the other side of the fender wall.

Working from the outside, I located the dimple and made a mark on the same horizontal plane but 1/2" toward the driver's seat. Using a 9/16" drill, I drilled a hole for the duct to pass through. (The image to the left shows both holes - the one in the channel and the one in the fender wall.) I started to dry fit the components together. I put the pipe into the channel hole and attached the 1/2" elbow. I inserted a straight piece of pipe through the fender wall and into the elbow. I determined how far I wanted the pipe to protude and cut the pipe to length. Attaching a 45 degree 1/2" copper elbow to the protruding pipe reduces the possibility of kinking by preventing the plastic drain tube from have to make a 90 degree downward bend. (The image to the right shows how the duct looks with all of the pieces dry fitted together.) The hole visible beneath the duct is where the scuttle drain tube exits the interior of the vehicle. I am going to use a T-fitting to connect the channel drain and the scuttle vent drain together where they exit through the rocker panels using a long tube. I will use clear plastic tubing (1/2" ID) so I can visibly see if and where any clogs may occur.

More to come!! I still need to fabricate a metal dam at the end of the channel to force the water to drain into the duct. This is on my schedule and I will post the results when I am finished. I don't want to braze any of the duct into place until I have finished cleaning and rebuilding this section of the car. I don't know what I will encounter and want to avoid putting "things" in my way.

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