Update here... holy &$&! that was a nightmare. Thought I was doing all the right things by letting the car soak with some penetrant fluid for a couple days and taking it slow trying to back the manifold bolts out. Wrong. Ended up snapping 10/12 bolts inside the head... For reference if anyone else gets into this situation the trial and error extraction process was as follows:
1) Tried to drill out a bolt and use an easy out... snapped the easy out inside the bolt even using very gradual pressure. F...
2) Had a friend with a welder. Tried to weld nuts onto the ends of the broken studs and back them out. By all internet accounts this method *should* work the majority of the time. Tried on like 6 of the studs and each time the bolt continued to shear off. The welds held firm but the bolts seem to be so brittle they snap in an instant. We also used a torch during this step to try to heat the head up, didn’t make any difference. Damn you Porsche for using M8 manifold bolts....
3) Resorted to drilling out.
- We made a drill guide out of the old manifold and marked drill bits to the correct depth.
- Drilled out the holes on the manifold to a 1/2” and had some custom bushings made to guide a “H” bit (luckily have friends who work in a machine shop). This is the correct size if you were going to re-tap the holes to the original size.
- Started with a small bit and progressively drilled out the bolt until using the H. Even with the hole completely drilled out it was still super tough to get a tap to go in cleanly due to tiny flecks of the steel bolt remaining. After 3 days and about 10 hours at this point I was getting impatient, so we resorted to boring out the holes more with a 21/64” bit and using helicoils instead. This was vastly easier as we had clean aluminum to tap into. The helicoils held firm and were easy to put in with the freshly tapped holes. All in the drilling/tapping process took 10-12 hours over 2 days with many swear words in-between.
Some notes: During this process there is limited clearance to drill straight holes, so we had to remove the thermostat and partially drain the coolant to get to one of them. I would also highly recommend getting some extended 6” bits as it was nearly impossible to reach a few of the holes without it. Cobalt is your friend here.
The only other major disruption we encountered was that snapped easy out from step 1. We tried using cobalt bits, carbide deburr tools and nothing was really working. Finally busted out the dremel and some aluminum oxide grind tools and after about 30 mins and 4-5 bits ground to dust we got through it. The grind bits seemed to work better since it allowed better precision and slowly removed material.
Finally, the fitment for the Manzo headers was fine with a bit of manipulation required of the exhaust to get everything to line up. The kit did not include the correct hardware however and the gaskets are sort of junk. Would highly recommend just purchasing new OEM gaskets to do this job and make sure you have all the right hardware.
All in all, 0/10 would do this again and would have just left the headers alone. But it’s done now! Filling up the car again with coolant today and hopefully back to driving.
