I have CAT 312 B excavator that I recently got. It is an awesome machine but a day or so ago I was digging out some stumps and the engine high temp light came on. All the coolant levels are good and the cooling fan is working good on the motor. I am wondering if I got it a bit warm because I was using the machine at lower RPM's (like at 1/4-1/3 full throttle) while doing heavier work as I am just learning on the machine. Does anyone have any suggestions as to the ideal RPMs for this work and any thoughts on the over temp issue? I used it for about 3 hrs this morning doing heavy digging of stumps without problems.