Mazda 323/626/929/GLC/MX-6/RX-7 1978-1989

Cooling System

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FLUID RECOMMENDATIONS



Use only a 50/50 solution of water and ethylene glycol antifreeze/coolant (or other type that is approved for aluminum engine parts).

LEVEL CHECK



See Figure 1

The coolant level should be checked regularly. Serious engine damage can occur if the engine overheats.


CAUTION
Check the coolant level when the engine is cold; serious injury could result from escaping steam or hot fluid if checked when hot. If your car is equipped with an electric cooling fan, make sure that the ignition switch is OFF. The cooling fan will automatically operate if the ignition switch is on and the engine coolant temperature is high, or if the wiring connector on the thermostat housing is disconnected.

  1. Depress the button on the thermal expansion tank (coolant recovery reservoir) safety cap, if there is one. Allow all of the pressure trapped in the system to escape.
  2.  


CAUTION
The radiator is not factory-equipped with a safety cap. Do not remove the radiator cap before removing the expansion tank cap, or when the engine is hot.



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Fig. Fig. 1: Remove insects and debris from the radiator fins

  1. Remove the expansion tank cap. The expansion tank should be 1 / 3 full, unless Full and Low marks are provided. The level should be well above the bottom of the tank when the engine is cold.
  2.  
  3. If it is not, carefully remove the cap from the radiator. The radiator should be full.
  4.  
  5. Add a 50/50 solution of ethylene glycol (or other suitable coolant) and clean water. If there was no coolant in the expansion tank, fill the radiator until the level is near the inlet port and install the radiator cap. Then, fill the expansion tank to the specified level, and secure the expansion tank cap.
  6.  

When checking the coolant level, the pressure cap should be examined for signs of age or deterioration. Check it for a worn or cracked gasket. If the cap doesn't seal properly, fluid will be lost and the engine will overheat. A worn cap should be replaced with a new one. The fan belt and other drive belts should be inspected and adjusted to the proper tension. (Please refer to the belt inspection and adjusting procedures, earlier in this section.)

Remove the radiator cap and run the tip of your finger around the inside of the filler neck. Check for excessive deposits of rust or scale around the filler neck lip and the filler port. Make sure the coolant is free of oil. Replace the coolant as necessary.

Hose clamps should be tightened, and soft or cracked hoses replaced. Damp spots, or accumulations of rust or dye near hoses, the water pump or other areas indicate possible leakage, which must be corrected before filling the system with fresh coolant.

Periodically clean any debris, leaves, paper, insects, etc. from the radiator fins. Pick the large pieces off by hand. The smaller pieces can be washed away with water pressure from a hose.

Carefully straighten any bent radiator fins with a pair of needle nose pliers. Be careful as the fins are very soft. Don't wiggle the fins back and forth too much. Straighten them once and try not to move them again.

DRAIN AND REFILL



See Figures 2, 3, 4, 5, 6 and 7

The engine coolant should be drained and the system flushed periodically. (Please refer to the recommended maintenance interval charts in this section.) New coolant mixed with the proper amount of clean water should be used, since antifreeze eventually becomes corrosive. While draining and refilling may only be required every 30 months/30,000 miles (48,309 km), the coolant should be inspected at 15 months/15,000 miles (24,155 km) and replaced if it shows signs of rust or corrosion. Good coolant appears in its original color, while coolant that is permitting corrosion will appear cloudy and darker than its original color.

Complete draining and refilling of the cooling system will remove accumulated rust, scale and other deposits. To make the job easier, park your car close to a faucet or other source of water and run a garden hose to the radiator.



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Fig. Fig. 2: With the engine cold, remove the radiator cap



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Fig. Fig. 3: With a suitable container in position, turn and open the radiator petcock

  1. With the engine cold, remove the radiator cap and air bleeder plug. (Air bleeder plugs are only installed on the RX-7.)
  2.  


CAUTION
When draining coolant, keep in mind that cats and dogs are attracted by ethylene glycol antifreeze, and are quite likely to drink any that is left in an uncovered container or in puddles on the ground. This will prove fatal in sufficient quantity. Always drain the coolant into a sealable container. Coolant should be reused unless it is contaminated or several years old.

  1. Drain the existing antifreeze/coolant into a suitable drain pan by opening the radiator and engine drain petcocks, or by disconnecting the bottom radiator hose at the radiator outlet. Before opening the radiator petcock, spray it with some penetrating lubricant, if necessary.
  2.  

On 1979-85 RX-7s, coolant is drained by removing the drain plug in the intermediate engine housing and by disconnecting the lower radiator hose. On 1986-89 RX-7s, coolant is drained by removing the intermediate housing drain plug and opening the radiator drain cock.

  1. Detach the hose at the base of the expansion tank (coolant recovery reservoir), and drain the old coolant into a suitable drain pan. Rinse the inside of this tank with clean water, if necessary, and reattach the hose.
  2.  

In order to drain the expansion tank, it may be helpful to temporarily remove it from the vehicle.

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Fig. Fig. 4: On RX-7 models, remove the drain plug from the intermediate engine housing



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Fig. Fig. 5: After flushing the system and closing the drain plug(s), properly refill the system using a proper mixture of antifreeze/coolant and water

  1. Set the heater control to the MAXIMUM heat position.
  2.  
  3. Flush the cooling system with clean water. (Directions for flushing and cleaning the system follow.)
  4.  
  5. Close the drain cocks or reinstall the drain plugs.
  6.  



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Fig. Fig. 6: Drain and refill the coolant in the expansion tank



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Fig. Fig. 7: Use an antifreeze tester, such as this syringe type, to test the level of protection

  1. Fill the cooling system with the proper amount and mixture of ethylene glycol or other aluminum-compatible coolant and water. Be sure to also add a fresh coolant mixture to the expansion tank. (The expansion tank and windshield washer fluid reservoir may be part of a dual reservoir; if so, be careful not to mix these two different types of fluid.)
  2.  


CAUTION
Do not use alcohol or methanol-based coolants!

  1. Run the engine at idle with the radiator cap removed to allow all the air to bleed out of the system. Add coolant as necessary to attain the proper level.
  2.  
  3. Install the radiator cap and the air bleeder plug (if equipped).
  4.  
  5. Check the level of protection with an antifreeze tester.
  6.  
  7. Start the engine and inspect for leaks.
  8.  

FLUSHING AND CLEANING THE SYSTEM



Commercial flushing agents may only be used if they are not harmful to aluminum components.

  1. Drain the cooling system and leave the drain cock or engine drain plugs open.
  2.  


CAUTION
When draining coolant, keep in mind that cats and dogs are attracted by ethylene glycol antifreeze, and are quite likely to drink any that is left in an uncovered container or in puddles on the ground. This will prove fatal in sufficient quantity. Always drain the coolant into a sealable container. Coolant should be reused unless it is contaminated or several years old.

  1. Set the heater controls to the MAXIMUM heat position.
  2.  
  3. Place a garden hose into the radiator filler opening.
  4.  
  5. Turn on the water supply and regulate the water so that the level in the radiator remains constant.
  6.  
  7. Start the engine and flush the system until the water leaving the radiator or engine is clear. This may take four or five minutes depending on the condition of the cooling system.
  8.  
  9. Stop the engine and allow the cooling system to drain completely.
  10.  
  11. Close the radiator drain cock and install the drain plugs (if equipped).
  12.  
  13. Fill the cooling system with the proper amount and mixture of ethylene glycol or other aluminum-compatible coolant and water.
  14.  


CAUTION
Do not use alcohol or methanol based coolants!

  1. Run the engine at idle with the radiator cap removed to allow all the air to bleed out of the system. Add coolant as necessary to attain the proper level.
  2.  
  3. Install the radiator cap and the air bleeder plug (if equipped).
  4.  
  5. Check the level of protection with an antifreeze tester.
  6.  
  7. Start the engine and inspect for leaks.
  8.  

 
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