I am chasing a sound of an exhaust leak. It is only noticable when the throttle is 25% or more, but it is pretty loud once it gets going. It sounded like it was coming from the right side. I installed a Fel-pro exhaust gasket on the right side, which only had RTV copper sealant on it and obvious signs of exhaust blow-by. The new gasket did not quiet down the exhaust.
I then removed the Fel-pro fiber gasket and installed aluminum reusable gaskets on both the left and the right. I also replaced both intermediate exhaust gaskets where the header meets up with the exhaust. I also installed self-tighening lock bolts on the exhaust manifolds.
After all that... the exhaust sound is still obvious. It is not clear why. I used a tube to check for air leaks and didn't really find any. I tightened up the exhaust manifold bolts a little more but no change.
I did a compression test in case the exhaust leak was coming from a head gasket. I didn't find any smoking guns. The only cylinder low-ish on compression was on the left side, and the leak sounds like it is on the right. Regardless, the "low" cylinder is only 105 while the rest were 120.
As long as I had all the spark plugs out I replaced them with new ones.
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