Initial Inspection and Diagnostic Overview

WARNING: Never spray water on a hot radiator. The resulting steam could cause personal injury.

CAUTION: Compressed air or water can be used to clean radiator fins. Do not exceed 138 kPa (20 psi). Pressures over 138 kPa (20 psi) will damage the radiator.

NOTE:
^ Check the outside of the radiator for bent fins or signs of leakage.
^ Do not attempt to temporarily seal the cooling system with a sealer type antifreeze or coolant additive. Remove any stones from between the fins. Clean loose debris and road film from the radiator core with a quality grease solvent and compressed air. Direct the stream of solvent at the front of the core for more efficient cleaning.

PRELIMINARY PROCEDURE
^ Remove the grille, fan guard, and fan shroud, to ensure a thorough cleaning.
^ Remove the radiator cap and look for plugging and scale on the inside of the tank. Replace a badly plugged radiator. Test the radiator and system.

1. Check the coolant level. If low, add recommended coolant as required.

CAUTION: When adding coolant, It Is NOTE that you use GM Goodwrench DEX-COOL (tm) coolant. If coolant other than DEX-COOL (tm) IS added to the system the coolant will require change sooner - at 50,000 km (30,000 miles) or 24 months.

2. Check the hose conditions and tighten the clamps if leakage is evident. Replace cracked, stripped, or corroded clamps.
3. Check the coolant hoses for spongy or cracked appearance. Replace deteriorated hoses or bursting could occur that would result in coolant loss and extensive damage due to overheating.
4. Check the radiator core for leaks and for accumulation of dirt which may obstruct the air passages and reduce heat transfer.
5. Check the coolant recovery tank for leaks.
6. Inspect the radiator rubber mountings and bumpers for deterioration and replace as necessary. Check the mounting bolts, supports, braces, also check for damage to the radiator core, side flanges, and supporting components.
7. Check for clearance between the fan blades, core, and shroud. Check the fan attaching bolts for tightness and make sure none are missing. Replace the fan if any blade is bent. The distance between the blades and shroud should be equal around the entire perimeter of the shroud. Adjust as necessary after any adjustment has been made to the fan or the fan mounting bracket and hub.
8. Inspect the filler cap seal for evidence of cracking, separation, or deterioration. Replace as required.
9. To assist in maintaining efficient heat dissipation, an occasional external flushing with water will remove the majority of dirt accumulation and foreign matter from between the core fins. Direct water under moderate pressure from behind the core to force debris out in the opposite direction of its entry. Direct the water stream in line with the fins to reduce the possibility of bending fins.
10. A radiator with a dirty, obstructed, or leaking core will cause the engine to overheat. A scale deposit inside the radiator is a result of using hard, high mineral content water in the cooling system. The effect of heat on the minerals in the water causes the formation of scale, or hard coating, on metal surfaces within the radiator, thereby reducing the transfer of heat. Some hard water will produce a silt-like deposit that restricts the flow of water. Replace a radiator that is plugged or has a heavy scale on the core.