Chrysler Full-Size Trucks 1997-2000 Repair Guide

Cooling System

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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 in personal injury. To avoid having scalding hot coolant or steam blow out of the radiator, do NOT remove the cap from a hot radiator. Wait until the engine has cooled sufficiently, 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 (with the cloth still in position), then turn and remove the cap.

level check



  1. Check the fluid level in the reservoir tank. Marks are provided. Check when the engine is at operating temperature. Add a 50/50 mix to maintain performance.
  2.  
  3. If it is necessary to add fluid, be sure to check level again soon.
  4.  
  5. A coolant level that drops consistently is usually a sign of a small, hard-to-detect leak. In most cases, a loose or damaged hose is the cause of the coolant level drop. However, check the heater core. Check the coolant for droplets of engine oil and the engine oil for milky white contamination (emulsified oil). This would indicate an internal leak (blown head gasket or worse), which must be addressed.
  6.  



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Fig. The coolant level is checked at the overflow tank. Check when hot. Level should be between the lines marked "MAX" and "MIN" or "FULL" and "ADD".

INSPECTION



At least once every two 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 been diluted with too much water, it won't protect against freezing.

The radiator cap should be examined for signs of age or deterioration. Fan belts should be inspected and, if necessary, adjusted to the proper tension (please refer to "Belt Tension Adjustment" in this section).

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. This must be corrected before filling the system with fresh coolant.

Check the overflow tank cap 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 coolant should be free of rust and oil. If oil is found in the coolant, there may be a major mechanical problem.



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Fig. Typical cooling system flow schematic



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Fig. Cooling systems should be pressure tested for leaks periodically

Checking The Radiator Cap

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 in the form of steam and the engine will overheat. If necessary, replace the cap with a new one.



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

Radiator Debris

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.

FLUID RECOMMENDATIONS



Coolant found in late model trucks is normally a 50/50 mixture of ethylene glycol and water which can be used year round. Always use a good quality antifreeze with water pump lubricants, rust and other corrosion inhibitors, and acid neutralizers.

Also available is another type of antifreeze, propylene glycol, which is non-toxic.

Keep in mind that should you decide to use a propylene glycol antifreeze, you should follow the antifreeze manufacturer's instructions closely. Do NOT mix ethylene and propylene glycol together, as the benefits of the non-toxic propylene glycol would be lost. In the event you decide to change to propylene glycol, make sure to completely flush the cooling system of all ethylene glycol traces.


CAUTION
When draining coolant, keep in mind that cats and dogs are attracted to ethylene glycol antifreeze, and are 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 coolant into a sealable container. Coolant may be reused unless it is contaminated or several years old.

FLUSHING & CLEANING THE SYSTEM



The system should be completely drained and refilled at least every two years in order to remove accumulated rust, scale and other deposits.


NOTE
Ensure that the engine is completely cool prior to starting this service.

  1. Remove the radiator and overflow tank caps.
  2.  
  3. Place a drain pan of sufficient capacity under the radiator and open the petcock (drain).
  4.  


NOTE
The petcock may be plastic and should be handled carefully. Before opening the radiator petcock, spray it with some penetrating lubricant.

  1. Drain the coolant from the engine block either by removing the drain plug or disconnecting the lower radiator hose.
  2.  
  3. When the system is completely drained, close the petcock and fill the system with a radiator flush. Clean water may also be used, but is not as efficient.
  4.  
  5. Idle the engine until the upper radiator hose gets hot. Be sure to put the heater on to circulate the water or cleaning fluid through the entire system.
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  7. Allow the engine to cool and drain the system again.
  8.  
  9. Repeat this process until the drained water is clear and free of scale.
  10.  
  11. Flush the overflow tank with water and leave it empty.
  12.  


NOTE
If you decide to add the antifreeze and water separately (instead of pre-mixing them), be sure that you add a sufficient amount of antifreeze, before topping off with water. Add a half-gallon of each at a time so that you won't find yourself with a filled system with too much of one or the other.

  1. Determine the capacity of the coolant system, then properly refill the cooling system with a 50/50 mixture of fresh coolant (antifreeze and water), as follows:
    1. Fill the radiator with coolant mixture until it reaches the radiator filler neck seat.
    2.  
    3. Start the engine and allow it to idle (heater on) until the thermostat opens (the upper radiator hose will become hot).
    4.  
    5. Turn the engine OFF and refill the radiator until the coolant level is at the filler neck seat.
    6.  
    7. Fill the overflow tank with the coolant mixture until the level is midway between the upper and lower level marks, then install the radiator cap.
    8.  

  2.  
  3. If available, install a pressure tester and check for leaks. If a pressure tester is not available, run the engine until normal operating temperature is reached (allowing the system to naturally pressurize), then check for leaks.
  4.  
  5. Check the level of protection with an antifreeze/coolant hydrometer.
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  7. After the system has cycled between operating temperature and cold a couple of times, check the overflow tank level and top up if needed.
  8.  



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Fig. Only remove the radiator cap when the engine is cool



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Fig. Radiator petcock components



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Fig. Cylinder block drain plug location (1)-typical



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Fig. Fill the system, run the engine, then check and top off as necessary

 
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