Mazda Trucks 1987-1993 Repair Guide

Cooling System

Print

See Figure 1


CAUTION
Never remove the radiator cap under any conditions while the engine is running! Failure to follow these instructions could result in damage to the cooling system or engine and/or personal injury. To avoid having scalding hot coolant or steam blow out of the radiator, use extreme care when removing the radiator cap from a hot radiator. Wait until the engine has cooled, then wrap a thick cloth around the radiator cap and turn it slowly to the first stop. Step back while the pressure is released from the cooling system. When you are sure the pressure has been released, press down on the radiator cap (still have the cloth in position) turn and remove the radiator cap.

At least once every 2 years, the engine cooling system should be inspected, flushed, and refilled with fresh coolant. If the coolant is left in the system too long, it loses its ability to prevent rust and corrosion. If the coolant has too much water, it won't protect against freezing.

The pressure cap should be looked at for signs of age or deterioration. Fan belt and other drive belts should be inspected and adjusted to the proper tension. (See checking belt tension).

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



Click image to see an enlarged view

Fig. Fig. 1: Cutaway view of a typical cooling system flow

FLUID RECOMMENDATIONS



See Figures 2 and 3



Click image to see an enlarged view

Fig. Fig. 2: Caution-antifreeze sticker located on the radiator-MPV



Click image to see an enlarged view

Fig. Fig. 3: Sticker showing quantity and coolant type located on the radiator crossmember

A 50/50 mixture of ethylene glycol and water for year round use. Use a good quality antifreeze that is safe for use with aluminum components.

LEVEL CHECK



See Figures 4, 5, 6 and 7

Most vehicles are equipped with a coolant reservoir tank (expansion tank) connected to the radiator by a small hose. When the engine is cold, look through the plastic tank; the fluid level should be between the FULL and Low lines. If the level is too low, remove the reservoir fill cover and add the proper mix of coolant until it reaches the FULL mark.



Click image to see an enlarged view

Fig. Fig. 4: Cutaway view of a typical cooling system flow



Click image to see an enlarged view

Fig. Fig. 5: Coolant overflow tank full and low level measurements



Click image to see an enlarged view

Fig. Fig. 6: Pull the cap and suction tube out of the coolant overflow tank to top off the cooling system



Click image to see an enlarged view

Fig. Fig. 7: Fill the engine coolant overflow tank to the FULL line

CHECK THE RADIATOR CAP



See Figure 8

While you are checking the coolant level, check the radiator cap for a worn or cracked gasket. It the cap doesn't seal properly, fluid will be lost and the engine will overheat.

Worn caps should be replaced with a new one.



Click image to see an enlarged view

Fig. Fig. 8: Be sure the rubber gasket on the radiator cap has a tight seal

CLEAN RADIATOR OF DEBRIS



See Figure 9

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 - 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.



Click image to see an enlarged view

Fig. Fig. 9: Periodically remove all debris from the radiator fins

DRAIN, REFILL AND FLUSHING



See Figures 10, 11, 12 and 13

Completely draining and refilling the cooling system every two years at least will remove accumulated rust, scale and other deposits. Coolant in late model trucks is a 50/50 mixture of ethylene glycol (make sure it is safe for aluminum components) and water for year round use. Use a good quality antifreeze with water pump lubricants, rust inhibitors and other corrosion inhibitors along with acid neutralizers.



Click image to see an enlarged view

Fig. Fig. 10: Turn the radiator draincock counterclockwise to open, draining the engine coolant



Click image to see an enlarged view

Fig. Fig. 11: Pouring coolant into the radiator until it reaches just below the filler neck

  1. Drain the existing antifreeze and coolant. It may be necessary to remove a splash shield, on some models, to gain access to the drain at the bottom of the radiator. Open the radiator and engine drain petcocks, or disconnect the bottom radiator hose, at the radiator outlet.
  2.  


CAUTION
When draining the coolant, keep in mind that cats and dogs are attracted by the 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.

Before opening the radiator petcock, spray it with some penetrating lubricant.

  1. Close the petcock or reconnect the lower hose and fill the system with water.
  2.  
  3. Add a can of quality radiator flush.
  4.  



Click image to see an enlarged view

Fig. Fig. 12: To refill the system with coolant, remove the radiator cap. NEVER remove the cap if the system is HOT

  1. Idle the engine until the upper radiator hose gets hot.
  2.  
  3. Drain the system again.
  4.  
  5. Repeat this process until the drained water is clear and free of scale.
  6.  
  7. Close all petcocks and connect all the hoses.
  8.  
  9. If equipped with a coolant recovery system, flush the reservoir with water and leave empty.
  10.  
  11. Determine the capacity of your coolant system (see capacities specifications). Add a 50/50 mix of quality antifreeze (ethylene glycol) and water to provide the desired protection to the level of the radiator filler port. Fill the coolant reservoir to the correct level. Install the radiator cap.
  12.  
  13. Run the engine to operating temperature.
  14.  
  15. Stop the engine. Allow the engine to cool and check the coolant level in the radiator. Add more coolant if necessary to the radiator.
  16.  



Click image to see an enlarged view

Fig. Fig. 13: Cooling systems should be pressure tested for leaks periodically

  1. Check the level of protection with an antifreeze tester, replace the cap and check for leaks.
  2.  

 
label.common.footer.alt.autozoneLogo