Find the coolant thermostat - 2005 Pontiac Montana SV6

• The thermostat on a Toyota RAV4 is located inside the engine coolant container. To reach the thermostat, open your hood and locate the coolant filler cap. Open the cap and then drain enough coolant so that the coolant level is below the thermostat housing. You should be able to identify the thermostat as a circular cap attached to the inside of the coolant container
  

The thermostat is a critical part of your coolant system, the system that circulates water and antifreeze (coolant) through the engine to keep it from over-heating. It is called a valve because it can open and close, depending on how hot the coolant is acting upon it.
The reason to put a thermostat in the coolant system is to allow the engine to reach normal operating temperature quicker (and therefore operate at peak efficiency) than without a thermostat.
When the engine is cold, the coolant is at normal outside temperature, so the thermostat is closed. This means when you start the car, the coolant starts circulating through the engine, but can't flow into the radiator. With a closed thermostat, the coolant just keeps circulating around in the engine until the car warms up, the coolant gets hot, and the heat acts upon the thermostat, causing it to open at a certain temperature (about 185-195 degrees F.), With the thermostat now open, the coolant can now enter the upper radiatior hose and flow down the radiator to cool itself down, before going back into the engine through the lower radiator hose.
So the thermostat is always found on a car in the area where the upper radiator hose connects to the engine. Thermostat closed-water can't circulate through the radiator. Thermostat open- coolant is forced through the hose into the radiator.
I hope this helps you understand the thermostat valve and why all manufacturers include them.

CTS 2003-2005 Removal Procedure...
3.2L Engines

1. Drain the cooling system.
   
2. Remove the radiator inlet hose from the coolant outlet pipe
   
3. Remove the bolt securing the oil level indicator tube, coolant outlet pipe and engine front lifting bracket from the cylinder head.
   
4. Remove the coolant outlet pipe from the thermostat housing.
   
5. Remove the O-ring seals from the coolant outlet pipe. Discard the O-rings.
   
6. Remove the intake manifold.
   
7. Remove the thermostat housing bolts (1) (image 1 attached)
   
8. Remove the thermostat housing with thermostat (2), from the engine (image 1 attached).
   
9. Remove and discard the seal ring.
   
10. Remove the thermostat from the thermostat housing (image 2 attached).

To install:

1. Install the thermostat into the thermostat housing.
   
2. Install a new seal ring.
   
3. Position the thermostat housing with thermostat, to the engine.
   
4. Install the thermostat housing bolts and tighten to 15 ft. lbs. (20 Nm).
   
5. Install the intake manifold.
   
6. Lubricate 2 new O-ring seals with coolant.
   
7. Install the new O-ring seals around the coolant outlet pipe grooves.
   
8. Insert the coolant outlet pipe (3) into the thermostat housing.
   
9. Install the bolt securing the oil level indicator tube, coolant outlet pipe and engine front lifting bracket to the cylinder head and tighten to 15 ft. lbs. (20 Nm).
   
10. Connect the radiator inlet hose to the coolant outlet pipe.
    
11. Fill the cooling system.

Image 1



Image 2

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REMOVAL

1. Remove upper intake manifold.
2. Partially drain cooling system below the thermostat level.
3. Remove upper radiator hose from outlet connector.
4. Remove coolant recovery system hose from outlet connector.
5. Remove coolant outlet connector bolts.
6. Remove thermostat assembly, and clean sealing surfaces.

INSTALLATION

1. Place the new thermostat assembly into the coolant outlet connector, aligning air bleed with the location notch on outlet connector.
2. Install coolant outlet connector with thermostat in position onto thermostat housing. Tighten bolts to 12.5 Nm (110 inch lbs.).
3. Install upper radiator hose.
4. Connect the coolant recovery system hose.
5. Install upper intake manifold.
6. Fill cooling system.
7. see thermostat mounting are below

JUST DRAIN COOLANT LEVEL BELOW THE THERMOSTAT. CATCH COOLANT IN A DRAIN PAN UNDER RADIATOR.THEN REMOVE RADIATOR HOSE FROM THERMOSTAT HOUSING ON THE CYLINDER BLOCK.THEN REMOVE THERMOSTAT HOUSING AND THERMOSTAT.CLEAN THERMOSTAT HOUSING SURFACE AND THERMOSTAT HOUSING SEALING SURFACE ON CYLINDER HEAD.INSTALL NEW THERMOSTAT IN PLACE,MAKE SURE THERMOSTAT AIR BLEED HOLE FACING LEFT SIDE UPWARD ON THE ENGINE.SOME THERMOSTAT HAS TOP STAMPED ON IT.MEANING MUST BE FACING UP.WHEN THERMOSTAT IN PLACE.TAKE NEW THERMOSTAT GASKET.PUT SEALER ON BOTH SIDES OF GASKET.THEN.PUT GASKET ON THERMOSTAT HOUSING.THEN PUT HOUSING IN PLACE TORQUE HOUSING BOLTS 16 - 20 FT LBS.WAIT 1 HOUR UNTIL GASKET SEALER CURE.THEN FILL UP COOLANT SYSTEM.BLEED COOLANT SYSTEM AND CHECK FOR LEAKS.

You didn't post your engine size so please choose the correct steps for your engine:

2.2L Engine



The thermostat is located in the lower radiator hose on the 2.2L engine




Remove the two retaining bolts for on the housing




Separate the housing halves to access the thermostat




Pull the thermostat out to remove it from the housing




The thermostat has an O-ring which goes around the center




Thoroughly clean the mating surfaces of the thermostat housing


When adding coolant, it is important that you use GM Goodwrench DEX-COOL® (orange colored, silicate free) coolant meeting GM specifications. On these vehicles, if silicated coolant is added to the system, premature engine, heater core or radiator corrosion may result. In addition, the engine coolant will require change sooner; at 30,000 miles or 24 months.

1. Disconnect the negative battery cable.
   
2. Properly drain and recover the coolant until the level is below the thermostat.
   
3. Unfasten the coolant outlet-to-inlet manifold attaching bolt and nut, then remove the outlet.
   
4. Remove the thermostat. Clean the inlet manifold and outlet mating surfaces.
   

To install:

1. Install a new O-ring onto the thermostat
   
2. Place the thermostat in the inlet manifold.
   
3. Attach the coolant outlet to the inlet manifold, using the bolt and nut. Tighten to 89 inch lbs. (10 Nm).
   
4. Refill the engine cooling system.
   
5. Connect the negative battery cable, then start the engine and check for coolant leaks.
   

CODE P0128- THERMOSTAT MALFUNCTION. POSSIBLE CAUSES 1. ECT SENSOR IS OUT OF CALIBRATION. 2. CHECK THE OPERATION OF THE THERMOSTAT IT MAY BE STUCK OPEN.3.INSPECT FOR LOW COOLANT LEVEL OR FOR AN INCORRECT COOLANT MIXTURE.

sound like """"sounds'''like thermostat issue! u might think about starting at that point!hope this helps. John

These are the steps to replace the thermostat but are applicable to remove and replace the housing also. 2.0L DOHC Zetec Engine WARNING Do not mix Standard (green) Coolant with Extended Life Coolant (orange). If mixing occurs, drain engine cooling system and refill with originally equipped coolant type. If this contamination occurs the service change interval on Extended Life Coolant will be reduced from 6 years/150,000 miles to 3 years/30,000 miles.

1. Disconnect the battery ground cable.
   
2. Drain the engine coolant to a point below the water thermostat.
   
3. Disconnect the connector from the camshaft position sensor.
   
4. Remove the bolts and move to one side the water hose connection.
   

Remove the water thermostat and seal from the water thermostat housing.

Inspect the seal and the water thermostat.

To install:

1. Replace the thermostat and seal into the housing.
   
2. Connect the connector to the camshaft position sensor.
   
3. Fill the cooling system.
   
4. Start the engine and check all hoses and connections for leaks. Allow the engine to warm up so that the water thermostat opens.
   
5. Stop the engine. Top off the coolant recovery reservoir as necessary to maintain minimum cold fill level.
   

2.0L SOHC Spi Engine

1. Disconnect the battery ground cable.
   
2. Remove the air cleaner outlet tube.
   
3. Drain the engine coolant to a point below the water thermostat.
   
4. Disconnect the water temperature indicator sender unit and the engine coolant temperature sensor electrical connectors.
   
5. Disconnect the upper radiator hose and the heater coolant hose from the water thermostat housing.
   
6. Remove the water thermostat housing bolts, the water thermostat housing, and the water thermostat.
   

To install:
NOTE Make sure all of the gasket surfaces are free of all gasket material. Make sure the tabs on the engage properly into slots in thermostat housing.

1. Install the thermostat housing bolts, thermostat housing and the thermostat.
   
2. Connect the upper radiator hose and the heater coolant hose to the thermostat housing.
   
3. Connect the water temperature indicator sender unit and the engine coolant temperature sensor electrical connectors.
   
4. Fill the cooling system with only Ford Premium Engine Coolant E2FZ-19549-AA (in Oregon F5FZ-19549-CC, in Canada, Motorcraft CXC-8-B) or equivalent meeting Ford specification in a 50/50 mixture with water.
   
5. Start the engine and check all hoses and connections for leaks. Allow the engine to warm up so that the water thermostat opens.
   
6. Stop the engine. Top off coolant recovery reservoir as required to maintain minimum cold fill level.
   

This code is for your Coolant Thermostat - It's detected that the Coolant Temperature is below the Thermostat Regulating Temperature

This code may mean one or more of the following has occurred:

• Low engine coolant level
• Leaking or stuck open thermostat
• Cooling fan running too much
• Faulty coolant temperature sensor (ECT)
• Faulty intake air temperature sensor (IAT)

Check the following to see if it resolves your problem:

• verify coolant strength and level
• verify cooling fan operation and replace if necessary
  
• verify ECT sensor operation and replace if necessary
• verify IAT sensor operation and replace if necessary
• if all above checks out, replace the thermostat