Still Have an Exhaust Leak
Well, I thought I fixed it, but it came back and haunts me while driving. I replaced the manifold-downpipe gasket, sealed it nice and snug. I took out the header and inspected it, no visible cracks found at all.
I did however notice that where the manifold bolts up to the engine, I used a brand new OEM gasket, that where on cylinder 1 exits, the gasket is square and the header comes down at a curve, exposing the gasket. I can also check on the header a "dummy" o2 sensor was put into the hole and may try for my o2 wrench and ensure that its secured well in there without stripping it.
Any suggestions? Go back to stock manifold perhaps?
2009 Cobalt LS XFE U74
Mods: K&N Typhoon Intake, Option Cat-Back Exhaust, Cosmo Short shifter, Maxxim Ahead 17X7's, MPx shorty antenna, FE5 Strut/shocks, Tein S Techs, Moog endlinks, Moog spring seaters, ZZP shorty header, LSJ downpipe, LNF front grille