Yesterday I did an exhaust repair to the 2006 Corolla LE. I fixed it using Permatex Muffler & Tailpipe Putty, part # 80333, followed by FiberFix Heat Wrap exhaust tape. The car had gotten very loud recently. To locate the leak I put the hose of the Craftsman 2 gallon portable shop vac in backwards so it blows, and put it in the tailpipe, and sealed the opening with duct tape. Once I turned on the vacuum cleaner and got under the car the noise and airflow directed me to the leak. Air and noise was blasting out of it. There was a jagged 1"x3/16" radial hole in one of the exhaust pipes at the edge of the joint where it fits inside one of the larger pipes,this part of the exhaust is before goes into the angle pipe and into the muffler. It was just in front of the rear passenger wheel. For such a small hole it was quite a loud and raspy noise with the car running and driving.
I cleaned the area thoroughly around the hole using and all sides of the pipe several inches away from the hole, using a steel wire brush and Simple Green to get rid of all the loose rust, dirt and scale. I would recommend do not spare time on the prep. Then followed it up with 91% alcohol on a cloth to clean it of dust and dry . For this I had my son helping by kneading the foil packet of Permatex putty for several minutes which is essential before using it, then squeezing the putty onto a wooden coffee stirrer each time I used the putty, passing him the empty stick over my shoulder. It was useful to have an extra pair of hands while under the car because it was cramped the putty starts to set up after a few minutes. I started by filling the the hole itself the narrrow part first, and building up layers and layers of the putty over the repair and on on either side, and also sealed around the pipe seam itself for good measure. I did not spare the putty on this. There are (2) 2-ounce packets and for the repair we used most of one packet. By the time we finished the putty was getting thick and harder to spread so did not finish the packet. Then I heated the putty for 8 minutes with a heat gun on 750F degrees setting. At that point it was dry to the touch, not tacky, smother and shinier but still slightly flexible. The Permatex putty is rated to 2000 degrees F.
Then I used the FiberFix Heat Wrap exhaust bandage. It is rated to 850 degrees F. With this you really need to work quickly. It's a 70" roll of seemingly fiberglass mesh tape gooped in sticky, red epoxy resin. The kit comes with rubber gloves but I had my own. You remove it from the pouch and must immediately soak it in a bowl of warm water for 5 seconds. This activates the glue. Then starting where the crack had been I wrapped it around where the crack had been and extending out several inches. Around the repair itself I wrapped it 5-6 times as recommended. As soon as I wrapped it you could feel it sticking to the Permatex putty and sticking to itself tightly. Wrapping it tightly is the key. It does not shrink during the curing process but it hardens quickly you have little time to work, and you have to use the whole roll at once. It is no exaggeration to say you only have a couple minutes after dunking it in the water, to get the FiberFix on there and tightly. They include several feet of a 3/4" wide aluminized, paper backed tape just to wrap around the exhaust tape to further tighten it before it cures. I found it fairly useless, does not stick to the Heat Wrap at all and barely sticks to itself, but used it anyway. Then I heated it with the heat gun in two, 10-minute sessions. It cures by heat. Then took off the aluminum tape. The directions say start the car and bring to an idle for 10 minutes, or else use a heat gun. I did not want to put exhaust pressure on the putty or the tape so soon after installing it. After the heat gun, and letting it cure an additional six hours, I then started the car and idled it for 15 minutes. No noise whatsover. I let the Corolla sit overnight without driving it, and took it out for a short trip at 10:30 AM this morning, parked at a grocery store for an hour, and drove home. It's completely silent. I was thinking about later covering it with an aluminum can and hose clamps to further reinforce it and seal against weather, but it seems like a bit of overkill.
....but what a great car.