Chrysler Full-Size Trucks 1997-2000 Repair Guide

Thermostat

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CAUTION
NEVER open, service or drain the radiator or cooling system when hot; serious burns can occur from the steam and hot coolant. Avoid physical contact with the coolant. Wear protective clothing and eye protection. Always drain coolant into a sealable container. Clean up spills as soon as possible. Coolant can be reused as long as it is reasonably clean and free of debris. If it appears contaminated or is more than one or two years old, it should be replaced.

REMOVAL & INSTALLATION




WARNING
Most cooling system hoses use "constant tension" hose clamps. When removing or installing, use a tool designed for servicing this type of clamp. The clamps are stamped with a letter or number on the tongue. If replacement is necessary, use only an OEM clamp with a matching ID.


CAUTION
Always wear safety glasses when servicing contact tension clamps.

  1. Locate the thermostat. This is located in a housing on the engine side of the upper radiator hose for all engines except the 4.7L. On the 4.7L engine, the thermostat is located on the engine side of the lower radiator hose.
  2.  
  3. Disconnect the negative battery cable (both batteries on diesels).
  4.  
  5. Drain the engine coolant from the block until the level is below the thermostat.
  6.  
  7. On V-10 engines, remove the support rod.
  8.  
  9. On most V-6 and V-8 models, the alternator must be removed or repositioned for access to the thermostat housing.
  10.  
  11. Remove the radiator hose from the thermostat housing.
  12.  
  13. Disconnect any sensors fitted to the thermostat housing.
  14.  
  15. Remove the retaining bolts from the thermostat housing. Note the lengths and location of each bolt for ease of installation.
  16.  
  17. Remove the thermostat housing, thermostat, and gasket, if fitted.
  18.  
  19. Note the relative positions of all components, especially gaskets and seals. Note the orientation of the thermostat in the housing.
  20.  

To install:

  1. Be sure the new thermostat is the correct one for your engine.
  2.  
  3. On V-10 engines, note that there is a rubber lip-type seal with a metal shoulder pressed into the intake manifold beneath the thermostat. The thermostat should fit snugly in the seal.
  4.  
  5. Clean the gasket or seal mating surfaces.
  6.  
  7. Paper gaskets must be replaced.
  8.  
  9. Install the thermostat, gasket or seals.
  10.  
  11. Install the thermostat housing on the engine.
  12.  


NOTE
The thermostat housing may have the word FRONT on it (3.9L, 5.2L, 5.9L); this goes towards the front of the vehicle.

  1. Be sure all components are properly seated before tightening.
  2.  
  3. Tighten the housing bolts to 18 ft. lbs. (24 Nm). Fasteners should be tightened evenly to avoid leaks or damage.
  4.  
  5. Reinstall the radiator hose onto the housing.
  6.  


NOTE
Ensure that you have secured the system drain plug(s) before refilling with coolant.

  1. Refill the radiator with a proper coolant mixture.
  2.  
  3. Connect the negative battery cable(s).
  4.  
  5. Start the engine and bleed the cooling system. Refer to "GENERAL INFORMATION AND MAINTENANCE."
  6.  
  7. Ensure that the thermostat is operational (by checking the upper radiator hose for warmth), and that there are no leaks.
  8.  



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Fig. Safe removal of constant tension clamps requires the proper tool



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Fig. Thermostat assembly (2.5L). Note bolt lengths and locations



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Fig. On 3.9L, 5.2L, and 5.9L (gas) engines, the gasket goes above the thermostat



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Fig. On the 4.7L engine, the thermostat is at the bottom of the engine



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Fig. V-10 thermostat assembly



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Fig. The diesel thermostat has two seals-1997-99 models



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Fig. Late model diesel thermostat assembly-2000 models



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Fig. Removing the thermostat from the manifold-typical



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Fig. A bit of paper towel will keep the bolt in the socket until the bolt hole is reached

 
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