How to replacing thermostat 2006 envoy

SOURCE: Replace the thermostat on 2002 GMC Envoy

4.2L Engine the thermostat and the neck where the hose goes on is one unit $25 at autozone

1. Remove the necessary coolant from the radiator.
2. Remove the alternator, Loosen the outlet hose clamp at the thermostat housing. Remove the outlet hose from the thermostat housing.
3. Remove the thermostat housing bolts.
4. Remove the thermostat housing from the engine block.
5. Clean all of the surfaces of the thermostat housing.
6. Clean the sealing surface of the engine block.

SOURCE: need steps on replacing thermostat on 2002 Envoy

Just replaced my 2005 envoy thermostat, and it might be the same. Here is what I had to do.
1. First, the thermostat was located on the driver side behind the alternator. The hose comes from the bottom of the radiator, not the top like most vehicles I have worked on.
2. You need to remove the belt by taking tension off of it. The tensioner is on the passenger side, under the steering pump. I used a socket wrench, placed in in the square hole on the tensioner, attached a pipe for leverage to the socket, and pulled until the belt was loose.
3. Next is removing the alternator. Best if you first disconnect your battery, as there is a hot line to the alternator. Disconnect the wiring harness located on the top. Remove the bracket bolts that hold the alternator. You might want to place something under the alternator to prevent it from damaging the small wheel under it as it will be heavy and free after you remove the bolts. I also removed the bracket to get full access to the hose and thermostat. There is a red wire that connects to the alternator, remove it and now the alternator can be pulled out and set to the side.
4. Once all this is out of the way, you can remove the hose to the thermostat (I assume you have drained the radiator).
5. Remove the two bolts hold the thermostat to the engine.
6 Replace the thermostat and reverse the order of the steps above.

I read that some can do this without removing the alternator or just loosening, but it is tight and makes the job a lot harder.

Hope this helps...Joe

Jeffrey Turcotte

• 8991 Answers
• Posted on Oct 08, 2010

SOURCE: how to replace a themostat

Please see my tip at http://www.fixya.com/cars/r5929960-s_thermostat .

Specific instructions for your car are as follows. Let me know if you get stuck or have more questions.

Removal & Installation

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.
   

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.

5.3L Engine
NOTE The thermostat is not serviceable separately. The water pump inlet and thermostat must be replaced as an assembly.

1. Drain the cooling system to a level below the thermostat.
2. Remove the radiator outlet hose.
3. Remove the water pump inlet bolts.
4. Remove the water pump inlet and thermostat from the water pump.

1. Install the thermostat and thermostat housing to the water pump.
2. Install the thermostat housing bolts. Tighten the bolts to 11 ft. lbs. (15 Nm).
3. Install the radiator outlet hose.
4. Properly fill the engine cooling system and check for leaks.