Exhaust soot
#16
#17
As many have stated, likely a cold leak. When the car cold starts moisture accumulates on the internal surfaces and eventually comes out the tailpipe as steam. Some factory mufflers actually have small weep holes to allow egress of accumulated moisture and reduce the probability of internal corrosion.
On a clamped section like that, you'll have evidence of a leak only when cold. To know if it's leaking when hot, you'd need to get under the car and check it while it's running. Larger leaks would be audible when close, but smaller leaks are easy to see when using something like a smoke stick. I've seen people do leak detection with a grill lighter too (carefully!).
On a clamped section like that, you'll have evidence of a leak only when cold. To know if it's leaking when hot, you'd need to get under the car and check it while it's running. Larger leaks would be audible when close, but smaller leaks are easy to see when using something like a smoke stick. I've seen people do leak detection with a grill lighter too (carefully!).