Hi Jim!
The covers on my 92' W140 300SEL has the same problems and was told by MB mechanic that the covers crack beacuse of the heat generated. Theres nothing you can do about it coz it will crack again after prolong driving with heat buildup. Can any members tell me if I am wrong and probably a solution coz everytime when the hood is up its an eye sore to see the beautiful machine spots a cracked valve cover.Cheers!