what is a safe running temperature for a Perkins 103-10 diesel engine.

I am worried that the engine running temperature is too hot. At half throttle the temperature gauge reads 200 f degrees, and the manuals lists thermostat operating temperature as 160 f to 180f.

 

At 180f the thermostat should be fully open. The gauge may not be accurate.
Try running without the thermostat for a while; if the gauge still reaches 200f the thermostat is not suspect.
Does the temp keep rising when the throttle is opened further?

 

Try an accurate thermometer, gauges are not always accurate.

 

Thank you for the help. The thermostat i have is not the original and opens at a higher temperature (around 180) and steadies at around 200. Thennit only rises further towards overheating if i push the throttle to full. I will try cleaning the heat exchanger.

 

For a closed system, 200F is not too hot.