How to Troubleshoot an Overheating Chevrolet 350 Engine

Inspect the metal fins on the front of the radiator for clogs, which are typically caused by insects. Pull any insects out of the fins with tweezers. Severe clogging will prevent air from passing through the radiator and cooling the antifreeze, resulting in overheating.

Twist off the radiator cap after allowing the engine to cool, then look into the radiator to observe the level of antifreeze. Pour antifreeze into the radiator until full if necessary.

With the radiator cap off, start the engine and look through the radiator opening while the engine warms. The radiator fluid level should drop noticeably and start moving once the engine is hot. The drop is caused by the thermostat at the end of the top radiator hose opening. Replace the thermostat if the fluid level does not drop.

Look for white smoke exiting from the exhaust pipe, which indicates a blown head gasket. The smoke is caused by antifreeze leaking into one or more cylinders, where it is ignited with the gasoline and converted to steam.

Observe the two seams between the water pump and the engine block while the engine is idling. Note that one seam is located on each side of the timing chain cover. Install new water pump gaskets if either seam leaks water.

Observe the tip of the water pump, where the water pump pulley attaches to the front of the water pump, while the engine is idling. The water pump’s bearing is damaged and the water pump must be replaced if antifreeze is visible in this area.

If you can't find the problem with any of the previous steps, then the radiator may be clogged with rust or sediment. In this case, the coolant isn't circulating, and not being cooled effectively. The radiator may need to be flushed or re-cored.