The thermostat is located inside the thermostat housing on the engine, where the upper radiator hose attaches, at the front of the engine bay on the passenger side of a 2018 Acadia equipped with the 3.6L V6.
Locating the thermostat housing
In the 2018 Acadia, the thermostat is part of the thermostat housing that sits on the engine block at the end of the cylinder head. The housing is typically on the front-right side of the engine bay, where the upper radiator hose meets the engine. Depending on trim and engine access, you may need to remove the engine cover or other components for a clear view.
To help you identify the thermostat housing, use these clues:
- Follow the large upper radiator hose from the radiator; it terminates at the thermostat housing on the engine.
- The housing is a small component secured to the engine with 2â3 bolts, and it may be plastic or metal.
- A bypass hose may also connect to the housing.
Conclusion: Locating the housing confirms the thermostat is inside, ready for inspection or replacement if needed.
Replacing the thermostat
If you need to replace it, follow these steps carefully to avoid coolant spills and air pockets in the cooling system.
- Tools and parts: new thermostat, gasket or seal, coolant, drain pan, basic hand tools, and possibly a hose clamp tool.
- Safety: Let the engine cool completely, then disconnect the negative battery terminal.
- Drain coolant from the radiator until the level is below the thermostat housing to minimize spills.
- Loosen and remove the hose clamp on the upper radiator hose and detach the hose from the thermostat housing.
- Remove the thermostat housing bolts and lift the housing away to expose the thermostat.
- Remove the old thermostat and clean the mating surfaces on the housing and engine block.
- Install the new thermostat with the correct orientation and install a new gasket or O-ring as required.
- Reattach the thermostat housing and the upper radiator hose. Tighten bolts to spec.
- Refill coolant and bleed the system of air by running the engine with the heater on and the radiator cap off until the level stabilizes; top off as needed.
- Check for leaks after the engine reaches operating temperature and recheck coolant level once cooled.
Conclusion: Replacing the thermostat is a straightforward task for a DIYer with basic tools, but it requires careful coolant handling and proper seating of the gasket to prevent leaks.
Editorial note
Always consult your vehicle's owner's manual or a service manual for exact torque specs and any model-specific steps.
Summary
The thermostat in a 2018 GMC Acadia sits inside the thermostat housing attached to the engine block at the end of the cylinder head, where the upper radiator hose connects, typically on the front passenger side of the engine bay. Locating the housing and following proper steps allows inspection or replacement with attention to coolant handling and air bleeding.