Dodge Colt/Challenger/Conquest/Vista 1971-1989 Repair Guide

Cooling System


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Fig. Fig. 1 Periodically remove all debris from the radiator fins

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Fig. Fig. 2 Cooling system maintenance item locations

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Fig. Fig. 3 Cooling systems should be pressure tested for leaks periodically

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

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Fig. Fig. 5 Be sure the rubber gasket on the radiator cap has a tight seal

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Fig. Fig. 6 Carefully loosen the radiator petcock with a pair of pliers

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Fig. Fig. 7 Once the radiator is full, remove the coolant reservoir tank lid ...

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Fig. Fig. 8 ... and fill to the correct level

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.

While you are checking the coolant level, check the radiator cap for a worn or cracked gasket. If the cap doesn't seal properly, fluid will be lost and the engine will overheat. Worn caps should be replaced with a new one.

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.


Coolant used (depending on winter temperatures) is usually a 50-50 mixture of ethylene glycol 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.


On models without an expansion tank, if the engine is hot, allow it to cool for several minutes to reduce the pressure in the system. Using a rag, turn the radiator cap 1 / 4 turn to the stop and allow all pressure to escape. Then, remove the cap. On models equipped with an expansion tank, check the level visually in the tank. It should be above the low mark. Never fill the tank over the upper mark.

Fill the radiator until the level is within 25mm of the radiator cap. It is best to add a 50/50 mix of antifreeze and water to avoid diluting the coolant in the system. Use permanent type antifreeze only.


Completely draining and refilling the cooling system every two years at least will remove accumulated rust, scale and other deposits.

  1. Drain the existing antifreeze and coolant. Open the radiator and engine drain petcocks, or disconnect the bottom radiator hose, at the radiator outlet.

On older models, before opening the radiator petcock, spray it with some penetrating lubricant.

  1. Close the petcock or re-connect the lower hose and fill the system with water. Move the dash control to the hot position.
  3. Add a can of quality radiator flush.
  5. Idle the engine until the upper radiator hose gets hot.
  7. Drain the system again.
  9. Repeat this process until the drained water is clear and free of scale.
  11. Close all petcocks and connect all the hoses.
  13. If equipped with a coolant recovery system, flush the reservoir with water and leave empty.
  15. Determine the capacity of your cooling system (see capacities specifications). Add a 50/50 mix of quality antifreeze (ethylene glycol) and water to provide the desired protection.
  17. Run the engine to operating temperature.
  19. Stop the engine and check the coolant level.
  21. Check the level of protection with an antifreeze tester, replace the cap and check for leaks.