Bud,

There is irony in your comment saying that you can't believe that MB did not have this fixed by 1991. Actually it is opposite. The M103 engine rarely blows a head gasket relative to the later M104 engine which is much more frequent.

In addition to that, There are no aluminum head/iron block engine models that I know of that do not experience a dose of this from time to time. The cast iron expands/contracts at a much different rate than aluminum, so things will sometimes happen.

Best of luck,