I have a 1997 SL600 V12, When checking the overheat problem I replaced the water pump, surpintine belt and thermostat. After putting the engine back together, I checked for combustion in the cooling system it showed positive.
I removed the cylinder heads and checked the head gaskets, cleaned heads and block checked with a straight edge and never found a problem. The cylinders didn't have any antifreeze in them. The cylinders have the appearance of a vehicle with very few miles.

Can anyone give me any suggestions on what to do, put head gaskets and put back together or replace the motor ?????