Exhaust fumes can only leak from three places:
- The pressed seams at either end of the muffler body
- The join seam (welded or crimped) along the length of the body
- The connection from the exhaust tube to the muffler
Below are some suggestions to test the entire system.
- Connect a shop-vac to the tailpipe so it blows air into the system. Hold your hands a few inches away from the exhaust line and feel for air blowing out. Spray the exhaust line with soapy water while a shop-vac blows air through the system and look for spots where bubbles form to locate the leak. However, be aware that air is not meant to be blown the opposite way through an exhaust system, and it could possibly blow contaminants back up into your engine.
- Once your car is completely cooled down, turn it on, listen for the leak, and run your hand along, but not on, the system to feel for air coming out. Start from the front of the vehicle and work your way back. Having someone occasionally rev the engine can help.
- If you still can’t find it, there’s another toolless method you can try. After letting the car cool down completely, spray possible problem areas with a mixture of soap and water. When you turn the car back on, the air coming out of the leak should theoretically blow bubbles or foam up.
Note that the tailpipe should not be blocked off to ‘pressurize’ the exhaust system. Mufflers are not designed to be pressure vessels; they are designed for exhaust gasses to pass through unimpeded, so blocking the tailpipe may cause damage to the muffler or other components which make up the system.
If the muffler has a slight leak when first fitted from either the end pressed seams or the seam running along the length of the muffler body there are some simple remedys;
- Lightly tap the seam at the point where the leak is occurring to slightly compress the joint, or;
- Use a small amount of ‘Maniseal’ or another exhaust sealant to seal up the slight leak.
- Over time the leak will usually seal itself with the carbon in the petrol/diesel but the two options above may help to eliminate this faster.