GM Firebird 1967-1981 Repair Guide

Cooling System

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FLUID RECOMMENDATIONS & LEVEL CHECK



See Figures 1 through 9

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Fig. Fig. 1: The coolant overflow reservoir is mounted on the inner fender and is attached to the radiator via a rubber hose



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Fig. Fig. 2: Cutaway view of a typical cooling system flow



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Fig. Fig. 3: Be sure the rubber gasket on the radiator cap has a tight seal



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Fig. Fig. 4: Periodically remove all debris from the radiator fins



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Fig. Fig. 5: Cooling systems should be pressure tested for leaks periodically



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Fig. Fig. 6: If not equipped with an overflow tank, remove the cap to check the coolant level in the radiator



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Fig. Fig. 7: If the level is low, add coolant until it is 2 in. below radiator neck



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Fig. Fig. 8: If equipped, check and add coolant through the overflow tank. Lift the lid ...



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Fig. Fig. 9: ... then add coolant to bring the level in the reservoir up to the FULL mark

It's a good idea to check the coolant level every time that you stop for fuel. If the engine is hot, let it cool for a few minutes, then check the level.

Dealing with the cooling system can be a dangerous matter unless the proper precautions are observed. It is best to check the coolant level in the radiator when the engine is cold. On early models this is accomplished by carefully removing the radiator cap and checking that the coolant is within 2 in. of the bottom of the filler neck. On later models, the cooling system has, as one of its components, a coolant recovery tank. If the coolant level is at or near the "FULL COLD" line (engine cold) or the "FULL HOT" line (engine hot) the level is satisfactory. Always be certain that the filler caps on both the radiator and the recovery tank are tightly closed.

In the event that the coolant level must be checked when the engine is hot on, engines without a coolant recovery tank, place a thick rag oveer the radiator cap and slowly turn the cap counterclockwise until it reaches the first detent. Allow all hot steam to escape. This will allow the pressure in the system to drop gradually, preventing an explosion of hot coolant. When the hissing noise stops, remove the cap the rest of the way.

If the coolant level is found to be low, add a 50/50 mixture of ethylene glycol-based antifreeze and clean water. On older models, coolant must be added through the radiator filler neck. On newer models with the recovery tank, coolant may be added either through the filler neck on the radiator or directly into the recovery tank.


CAUTION
Never add coolant to a hot engine unless it is running. If it is not running you run the risk of cracking the engine block.

The radiator hoses and clamps and the radiator cap should be checked at the same time as the coolant level. The radiator cap gasket should be checked for any obvious tears, cracks or swelling, or any signs of incorrect seating in the radiator filler neck.

Check the freezing protection rating at least once a year, preferably just before the winter sets in. This can be done with an antifreeze tester (most service stations will have one on hand and will probably check it for you, if not, they are available at an auto parts store). Maintain a protection rating of at least -20ordm;F (-29ordm;C) to prevent engine damage as a result of freezing and to assure the proper engine operating temperature.

DRAIN & REFILL



See Figures 10, 11 and 12

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Fig. Fig. 10: If the radiator must be drained, locate the drain valve (arrow) on the underside of the radiator ...



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Fig. Fig. 11: ... and loosen it until coolant flows out of the valve



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Fig. Fig. 12: The radiator drain valve may be stubborn and require the use of a pair of pliers to loosen it

The cooling system should be drained, thoroughly flushed and refilled at least every 30,000 miles. This should be done with the engine cold.

  1. Remove the radiator cap and the expansion tank cap (if so equipped).
  2.  
  3. With the caps removed, run the engine until the upper radiator hose is hot. This means that the thermostat is open and the coolant is flowing through the system.
  4.  
  5. Turn off the engine, place a large container underneath the radiator and open the drain valve at the bottom of the radiator.
  6.  

Drainage may be accelerated by removing the drain plugs on the sides of the cylinder block.

  1. Close the drain valve and add water until the system is filled.
  2.  
  3. Repeat Steps 3 and 4 several times until the drained liquid is nearly colorless.
  4.  
  5. Tighten the drain valve and fill the radiator with a 50/50 mixture of antifreeze and water.
  6.  
  7. With the radiator cap still removed, run the engine until the upper radiator hose is hot. Add coolant if necessary, replace the caps and check for any leaks.
  8.  

 
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