To add my two cents to these details..I RR'd my head 3 times replacing the bolts at first, then not.

On the first head removal the M104 which was done by Mercedes Certified after a total wreck..(all new glass, headliners and tons of parts.) This bolt had no torque at all on the outside rear passenger side head bolt. Was hand tight..The others were all properly torqued. It had tiny leaks of both coolant and water but no mixing only to the outside of the block above the exhaust. Cause appeared to be very small pitting, possibly not corrected. It had valve work only to the intake valves, not the exhaust (appeared to be a cheap-o shortcut head job)

I replaced properly with full machine work and not a drop since, from the head..I suspect I do have some minuscule leaking from the valve cover gaskets, about one drop per week. Nothing from the timing cover! I feel so accomplished