Ingersoll Rand XP750WCA 1993 model with cat 3306dit engine

Sir, 

 I recently attended complaint in the above said model compressor. The problem is as follows, 

1. The compressor is running up to 3 hours at full rpm and and the temperature reaches 100°c. At this time the engine shutdown and the radiator water overflows from overflow tube. 

2. Again the engine will not start up to half an hour. And then it runs for some time after filling the radiator water. 

So I have checked and done the following. 

1. Checked the control system and found the speed control pneumatic cylinder line is blocked and the engine always runs at full rpm. So corrected it. 

2. Then the water temp is too high suspected the thermostat valve is malfunctioning. So replaced the thermostat valave. 

3. Drained radiator water and filled the coolant oil and done all oil services. Replaced all filters. 

Now the speed control is ok and the temperature remains 80degree Celsius but the engine gets shutdown and the radiator overflows.  So What should be the problem? Please help me to solve the problem.