Chevrolet Blazer/Jimmy 1969-1982 Repair Guide

Thermostat

Print

The factory installed thermostat is a 195°F unit.

Poor heater output and slow warming is often caused by a thermostat stuck in the open position; occasionally one sticks shut causing immediate overheating. Do not attempt to correct a chronic overheating condition by permanently removing the thermostat. Thermostat flow restriction is designed into the system; without it, localized overheating due to turbulence may occur.

REMOVAL & INSTALLATION





Click image to see an enlarged view

Fig. Fig. 1 To remove the thermostat, disconnect the hoses from the thermal vacuum switch



Click image to see an enlarged view

Fig. Fig. 2 Remove the thermostat cover bolts



Click image to see an enlarged view

Fig. Fig. 3 Remove the thermostat cover and set it aside



Click image to see an enlarged view

Fig. Fig. 4 Remove the old gasket material ...



Click image to see an enlarged view

Fig. Fig. 5 ... then remove the thermostat from the engine

Gasoline Engine
  1. Drain approximately 1 / 3 of the coolant into a clean container. The coolant can be used again, unless it is very dirty. This will reduce the coolant level to below the level of the thermostat housing.
  2.  


CAUTION
When draining engine coolant, keep in mind that cats and dogs are attracted to ethylene glycol antifreeze and could 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 should be reused unless it is contaminated or is several years old.

  1. It is not necessary to remove the upper radiator hose from the thermostat housing. Remove the 2 retaining bolts from the thermostat housing. Remove the 2 retaining bolts from the thermostat housing (located on the front top of the V8 intake manifold and directly in front of the valve cover on six cylinder engines) and remove the thermostat.
  2.  
  3. To test the thermostat, place it in hot water, 25° above the temperature stamped on the valve. Submerge the valve and agitate the water. The valve should open fully. Remove the thermostat and place it in water 10° below the temperature stamped on the valve. The valve should close completely.
  4.  
  5. Installation is the reverse of removal. Use a new gasket and sealer. Refill the cooling system and run the engine, checking for leaks.
  6.  

Diesel Engine

The thermostat is located in the coolant crossover pipe at the front of the engine.

  1. Disconnect the battery cables.
  2.  
  3. Drain the cooling system until the coolant level is below that of the thermostat.
  4.  
  5. Remove the water outlet attaching bolts and remove the outlet.
  6.  
  7. Remove the thermostat.
  8.  

To install:

  1. Make sure the sealing surfaces are clean and then place a 1 / 8 in. bead of RTV sealant around the coolant outlet sealing surface on the thermostat housing.
  2.  
  3. Place the thermostat in the housing and install the coolant outlet while the RTV sealant is still wet.
  4.  
  5. Connect the batteries and refill the cooling system.
  6.  

 
label.common.footer.alt.autozoneLogo