Had blown head gasket in Sept., supposedly caused from sitting in a garage for 2 years and then going into daily use? Tore down, had head resurfaced (wasn't cracked, just had some inperfections), purchased all recommended new parts for putting back together. Finally after 4 months got up and running Sat. Ran great. Watched temp gauge. It would go from 70 to between 100 and 110 and then back down within seconds. Parked it until last night. Reburped cooling system. Started and let run for about 30 minutes, drove about 10 miles and about a mile from home started running rough and blowing white smoke. I got a real sick feeling that something really bad had just happened, like another blown head gasket, even though the temp guage showed more leveling out and stayed between 90 and 100. My father in law, a 50 yr plus diesel mechanic (although not familiar with Mercedes) came by this morning. The car starts and initially ran a little rough, but in a few seconds leveled out and is running really smooth right now. There is still some white tailpipe smoke, not a lot. It smells like fuel, not sweet smelling at all. He observed that there is exhaust coming out of the cooling system. With the cap off, it pours white smoke as soon as the car starts. There seems to be little water in the radiator hose even after reburping system and adding another 1/2 gal of coolant last night. It seems like compression in the engine is pushing the water out of the block. Do I have ANY options or any suggestions other than to tear this whole thing down again? There are so many variables, I am confused and don't know where to start because I don't know what went wrong and what to do different. We did everything by the manual, and checked and rechecked every move and part and procedure. HELP!