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Short Summary
Main recommendation: To find and repair an exhaust leak without a welder, pressurize the exhaust with a leaf blower, shop vac, or air compressor, locate the leak with soapy water bubbles, then seal it with high-temperature exhaust putty, a muffler bandage (exhaust wrap), or an exhaust band clamp. The video demonstrates this on a Mustang V6 with a single exit exhaust, then shows the clamp and wrap methods on the presenter's truck.
Key Points
- Pressurizing the exhaust is the key step for locating leaks; the video says the engine doesn't need to be running, but it must be completely cold before spraying soapy water, to avoid warping or cracking the exhaust.
- On this car, the biggest leak was at the exhaust manifold flange, and the presenter guessed that was likely the main source of the exhaust noise.
- Leaks can cause check engine lights, lost fuel economy, rough running, and exhaust fumes entering the cabin, according to the video.
- Putty suits exhaust manifolds and pipes that get very hot; the wrap and clamp were demonstrated on a rust hole example cut into the presenter's truck exhaust.
- Sealing the leaks removed the exhaust noise and fumes in the Mustang, and the presenter says his truck repair from about six years earlier still holds.
Details Worth Noting
- Concrete instructions:
- Use a leaf blower, shop vac (with the hose reversed to blow), or air compressor to push air into the exhaust. On a single exit exhaust, tape the hose into the tailpipe. On a dual exit exhaust, mount the blower in one tip and fit a nitrile glove over the other tip, taped off.
- Make sure the engine is completely cold before spraying. Mix dish soap and water until very sudsy, then spray the entire exhaust manifold, underneath pipes, and especially welds, flanges, and connectors. Bubbling marks the leak. Use plenty of soap.
- Check both sides of the engine and the underside of the car. Remove the intake if needed to access the manifold on the other side, as the presenter did.
- Do not seal a small hole at the end of a stock muffler; it is a factory drain hole for water.
- Clean the leak area with sandpaper or a metal wire brush, then wipe with isopropyl alcohol to remove dust, grease, and dirt.
- Before applying putty, flip the vacuum hose to suck air out of the exhaust so the putty is drawn into the cracks. Stir the putty into a paste like concrete, press it into each leak, then pack more around it. Wipe off excess while wet with soapy water.
- Let the putty cure for 2 to 24 hours depending on heat; a heat gun or hair dryer can speed this. Do not start the engine before the putty cures, since the pressure can blow it out. To confirm the cure, press a fingernail into the putty; it should not dent.
- For a rust hole, use a stainless steel exhaust clamp by wrapping it around the pipe, adding the bolts, and tightening. For an exhaust wrap, heat the exhaust until almost too hot to touch, wrap the tape flat with about a one-inch overlap, keep it taut, then harden with a heat gun for a few minutes rather than running the engine.
- The total hands-on time for the Mustang repair was about 15 to 20 minutes, excluding cure time.
- Extra supplies: gloves, tape, sandpaper, a metal wire brush, and isopropyl alcohol.
- The putty is rated for 2,400 degrees of continuous heat, according to the product shown.
- The presenter notes that the wrap instructions call for running the engine, but he avoided this because positive pressure could blow out the material.
Bottom Line
Finding a leak with air and soapy water is the fastest part; the repair choice depends on the size and location of the leak, with putty best for manifold and flange leaks and clamps or wraps for rust holes.
