Glad to hear the problem was solved. The important thing for others to remember. Is that I believe there were no other indications of a cracked head other than the operational temperature was generally too high to be comforatable with.

Tough call to pull the head if there is nothing else indicating the fault. On the other hand you pretty well had already covered probably all other possible external faults.

It is a real shame mercedes did not get a good reliable head casting in production with the 603 type initially. The result has been a lot of grief for a lot of people.