Some would say, "duh", but let me finish. I replaced the front catalytic converter donut gasket this weekend on the Honda. It was sticking to the converter flange and creating a squeaking sound. This is addressed in a TSB by Honda, but mine is out of warranty coverage for that.
Anyway, I had to remove the converter from the vehicle completely (thank you, Honda, for attaching it with bolted flanges on BOTH sides). I could look up into the exhaust manifold and into the throat of the converter and the pipes were spotless on the inside. They looked like they could be new parts. But the donut gasket had a tinge of black soot at the bottom of it.
I ask because I think that there was a slight leak there. After the job, and during acceleration, I noticed that the engine has a more refined sound to it now. There was a slight "whease" that's gone. If there was an air leak there, would that contribute to the formation of the black soot? Because it's only at that gasket...not anywhere else in the system.
Interestingly, the exhaust manifold is really nice. It's a tubular steel manifold, with mandrel bends (no crushed kinks), and all branches were of an equal length. The two end cylinders' branches turn straight down to the collector and the two middle cylinders' branches bow out a little before turning down. It looks just like a "shorty header" that one might replace an old school cast iron manifold with.
Anyway, I had to remove the converter from the vehicle completely (thank you, Honda, for attaching it with bolted flanges on BOTH sides). I could look up into the exhaust manifold and into the throat of the converter and the pipes were spotless on the inside. They looked like they could be new parts. But the donut gasket had a tinge of black soot at the bottom of it.
I ask because I think that there was a slight leak there. After the job, and during acceleration, I noticed that the engine has a more refined sound to it now. There was a slight "whease" that's gone. If there was an air leak there, would that contribute to the formation of the black soot? Because it's only at that gasket...not anywhere else in the system.
Interestingly, the exhaust manifold is really nice. It's a tubular steel manifold, with mandrel bends (no crushed kinks), and all branches were of an equal length. The two end cylinders' branches turn straight down to the collector and the two middle cylinders' branches bow out a little before turning down. It looks just like a "shorty header" that one might replace an old school cast iron manifold with.
