We see an awful lot of busted exhaust bolts in these heads. And we see a lot of failed repairs. We also see a lot of corroded flanges that create significant exhaust leaks, as well as grooved flanges from the factory steel gaskets digging into the flanges as a result of exhaust manifold/header shuffling from heat, vibration and expansion & contraction.
On 3.4 Cayman and 3.6 911 heads we are seeing some with low spots around the large secondary air passage. In some cases this dip is as deep as .5mm.
As the photos indicate we’re Bridgeport Mill fixtured to remove broken exhaust studs and machine for Time-Serts or Heli-Coils.
We can also repair damage done by other shops in their attempts to repair busted studs as these photos show.
Click on photo for larger image.