Leaking Head gasket on 99 S500???

[rickwomble]

The plastic connector in the coolant line at the firewall broke and my 99 S500 overheated recently. I replaced the part but now it is overheating quickly and making burping noises like air is leaking into the coolant. I did a leakdown test and found that air is leaking back into the coolant revervoir from cylinder #7. This leads me to believe that I have either a cracket head or leaking head gasket. Is it definitive that the head is cracked or the head gasket is bad or is there any other test I should do before pulling the head off and having it checked for cracks and replacing the head gasket etc?

I've also heard rumors that you can pull and replace the head without pulling the intake manifold on some V8s. Is this possible on my engine?Any experinced advice would be appreciated.