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Eric, Automotive Repair Shop Manager
Category: GM
Satisfied Customers: 29701
Experience:  20+ yrs. experience as repair shop manager and technician.
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How to change thermostat on a GMC Envoy XL SLT 4.2L I6?

Customer Question

how to change thermostat on a GMC Envoy XL SLT 4.2L I6?
Submitted: 5 years ago.
Category: GM
Expert:  Eric replied 5 years ago.

below are directions.

4.2L Engine

  1. Remove the necessary coolant from the radiator.

  2. Remove the alternator, as outlined in the Engine Electrical Section.

  3. Loosen the outlet hose clamp at the thermostat housing. Remove the outlet hose from the thermostat housing.

  4. Remove the thermostat housing bolts.

  5. Remove the thermostat housing from the engine block.

  6. Clean all of the surfaces of the thermostat housing.

  7. Clean the sealing surface of the engine block.

To install:

View Full Image

Thermostat mounting—4.2L engine

  1. Install the thermostat housing to the engine block.

  2. Install the thermostat housing bolts and tighten to 89 inch lbs. (10 Nm).

  3. Lubricate the inner diameter of the radiator hose with engine coolant.

  4. Install the outlet hose to the thermostat housing. Secure the hose with the clamp.

  5. Install the alternator.

  6. Fill the cooling system with specified coolant and concentration.

  7. Inspect all sealing surfaces for leaks after starting the engine.

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