Check the outside of the radiator for bent fins or signs of leakage. Repair leaking radiator cores.

Do not seal temporarily with a sealer type antifreeze or coolant additive. Remove any stones between the fins. Clean loose debris and road film from the radiator core with a quality grease solvent and compressed air.

Remove the grille, 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 as described in SECTION 6B1.
1. Check the coolant level. If low, add recommended coolant as required.
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, which 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 recovery tank for leaks. Plastic bottles may develop cracks from being damaged by flying objects.
6. Inspect the radiator rubber mountings and bumpers for deterioration and replace as necessary. Check the mounting bolts, supports, braces, tie rods, and stabilizer rods. Components should be securely fastened in place if mounting bolts are missing, loose, or stripped. Check for damage to the core, side flanges, and supporting components.
7. Check for clearance between the fan blades, core, and shroud. Make sure the fan attaching bolts are tight and that none are missing. Replace the fan if any blade is bent.

8. Inspect the filler cap for evidence of cracking, sep­aration, or deterioration. Replace as required.
9. An occasional external flushing with water will remove the majority of dirt accumulation and for­ eign matter from between the core fins and will help to maintain efficient heat dissipation. Direct water under moderate pressure from behind the core to force debris out in the opposite direction of its entry. Remove the grille and fan shroud and direct the water stream in line with the fins to reduce the possibility of bending fins.

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 which restricts the flow of water. Replace a radiator that is plugged or has a heavy scale on the core.

To remove the hardened scale, a direct chemical action is necessary. A flushing compound at the speci­fied rate of 30 grams per liter (4 oz. per gallon) of radiator capacity should be added to the coolant solution in the form of a dissolved solution while the engine is running. Operate the engine for 15 minutes or until it reaches normal operating temperature, then drain and flush the system with clean water.

There are various types of flushing compounds com­mercially available, but they should be obtained from a reliable source. Most compounds attack metals and should not remain in the engine for more than a few minutes. A neutralizer should be used in the cooling system immediately after a descaling solvent is used.

For extremely hard, stubborn coatings, such as lime scale, use a stronger solution. The corrosive action of a stronger solution will affect the thin metals of the radia­tor, thereby reducing its operating life. A complete flush­ing and rinsing is mandatory and must be accomplished skillfully.

After the solvent and neutralizer have been used and the cooling system is flushed, drain the entire system and fill it with clean, soft water plus a high boiling type antifreeze that meets GM 6038-M specifications. After filling the cooling system, check for radiator, hose, and engine coolant leaks.



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