I have had the same problem with my 86 300E for a few years now. It turned out to be a leak in the heater core. It waas only recently that the leak was bad enough to drip while the car was parked. I bypassed the core and now I am not loosing any coolant. You might check that before tearing into the head.

__________________
I got too many cars!! Insurance eats me alive. Dave

78 Corvette Stingray - 3k
82 242 Turbo Volvo - Manual - 270k
86 300e 5 speed manual - 210k
87 420sel - 240k
89 560sl - 78k
91 420sel - 205k
91 560sel - 85k
94 GMC Suburban - 90k
97 Harley Davidson Heritage Softail - 25k
00 GMC Silverado 1 ton 30k