How to Replace Thermostat 88-98 GMC Sierra K1500 V8 5.7L
Difficulty: Intermediate · About 35 min · Gmc Sierra K1500
Replace the thermostat on a 1988–1998 GMC Sierra K1500 with the 5.7L V8 by draining coolant, opening the thermostat housing, and refilling the cooling system.
Tools you will need
- Funnel
- 13mm Socket
- Socket Extensions
- 14mm Socket
- Drain Pan
- Ratchet
- Anti-Freeze
Parts and supplies
- Thermostat
- Coolant
Steps
Drain coolant from the cold engine
Park on level ground and allow the engine to cool completely. Place a drain pan below the radiator, remove the radiator cap only when cold, and open the radiator drain. Let the coolant drain below the thermostat housing, then close the drain plug.
Remove the thermostat housing
Remove the 14 mm housing nut and the two 13 mm housing fasteners. Lift the housing away and note the thermostat orientation before removing it from its recess.
Install the new thermostat
Clean the housing and mating surfaces without gouging them. Seat the new thermostat in the same orientation as the original, place the housing over it, and reinstall the two fasteners and ground connection.
Refill and check the cooling system
Fill the coolant reservoir with the specified mixture using a funnel and close the radiator cap. Follow the vehicle's bleeding procedure, monitor engine temperature, and let the engine cool fully before rechecking the coolant level and inspecting for leaks.
Check your vehicle’s repair manual for exact specifications and fit.