Originally Posted by Paul61

I have a 1986 560sl and It works fine till it gets at full operating temperature. After shutting it down to refuel or some similar short period of time and then restarting the engine exhibits spark knock. I had taken it to an independant garage and the same problem is still evidenced. It seems that the power is some what reduced when the spark knock is evidenced. I have noticed what are apparently thermal sensors in the coolant water jacket with electrical connectors attached to some and vacuum lines to others. Suggestions as to what needs to be done or replaced would be greatly appreciated.