86 RENR5042-02 Troubleshooting Section k. If the cooling system for this application is equipped with an aftercooler, check the aftercooler. A restriction of air flow through the air to air aftercooler can cause overheating. Check for debris or deposits which would prevent the free flow of air through the aftercooler. e. Consider high altitude operation. The cooling capability of the cooling system is reduced at higher altitudes. A pressurized cooling system that is large enough to keep the coolant from boiling must be used. Make sure that the settings for the engine are correct for the altitude. l. D. Check the Engine’s Exhaust System. m. The engine may be running in the lug condition.
When the load that is applied to the engine is too large, the engine will run in the lug condition. When the engine is running in the lug condition, engine rpm does not increase with an increase of fuel. This lower engine rpm causes a reduction in coolant flow through the system. Check for a restriction in the exhaust system. A restriction of the air that is coming out of the engine can cause high cylinder temperatures. Expected Result: A thorough inspection revealed a problem. B. Check for High Ambient Air Temperature Results: Yes – A thorough inspection revealed a problem. a. Determine if the ambient air temperature is within the design specifications for the cooling system.
When ambient temperatures are too high for the rating of the cooling system, there is not enough of a temperature difference between the ambient air and coolant temperatures. Repair: Repair the problem. Ensure that the repair eliminates the problem. STOP. b. Determine the cause of the high air temperature. Make corrections, when possible. C. Check for High Inlet Air Restriction and/or High Altitude a. When inlet air pressure is low, the turbocharger works harder in order to achieve the desired inlet manifold pressure. This increases inlet air temperature. b. Measure the inlet air pressure while the engine is operating under load.
For specific data, refer to the Technical Marketing Information for the engine. c. Check for plugged air filters. Check for obstructions to the air inlet. A restriction of the air that is coming into the engine can cause high cylinder temperatures. High cylinder temperatures cause higher than normal temperatures in the cooling system. d. Replace the air filters and/or remove the obstruction from the air inlet.