Where is the thermostat located on my 2004 chevy colorado z71 3.5litre engine

Disconnect upper radiator hose from engine and the thermostat should be there. I have worked on vehicle that had thermostat underneath so if it is not located in upper radiator hose it will be in the bottom hose

. .It's on the side of the engine under intake manifold in the middle between the starter and the alternator .

Evaporative Emission (EVAP) Canister Purge Solenoid
Left side of the engine below the intake in back of the alternator

It could be th Camshaft Position Actuator Solenoid located on top of the engine check it out if oil in the plug then its bad and also on the part there is 3 sets of screens if any missing then the part is bad and screens will be in your oil pan so change your oil asap

Check this procedure for Canyon, Colorado 2004-2005 - Removal & Installation

1. Drain the cooling system.
   
2. Raise and support the vehicle only high enough to access the thermostat housing through the wheelhouse.
   
3. Remove the left wheelhouse liner.
   
4. Remove the radiator inlet hose from the thermostat housing.
   
5. Remove the thermostat housing bolts.
   
6. Remove the thermostat housing from the engine block.
   
7. Clean and inspect the thermostat housing.
   
8. Clean and inspect the sealing surface of the engine block.

To install:

1. Position the thermostat housing to the engine block.
   
2. Install the thermostat housing bolts and tighten to 89 inch lbs. (10 Nm).
   
3. Connect the radiator inlet hose to the thermostat housing.
   
4. Install the left wheelhouse liner.
   
5. Lower the vehicle.
   
6. Fill the cooling system.
   
7. Inspect all sealing surfaces for leaks after starting the engine.

1. Drain the cooling system.
   
2. Raise and support the vehicle only high enough to access the thermostat housing through the wheelhouse.
   
3. Remove the left wheelhouse liner.
   
4. Position the hose clamp pliers to the clamp to remove the radiator inlet hose from the thermostat housing.
   
5. Remove the thermostat housing bolts.
   
6. Remove the thermostat housing from the engine block.
   
7. Clean and inspect the thermostat housing.
   
8. Clean and inspect the sealing surface of the engine block.

To install:

1. Position the thermostat housing to the engine block.
   
2. Install the thermostat housing bolts and tighten to 89 inch lbs. (10 Nm).
   
3. Connect the radiator inlet hose to the thermostat housing.
   
4. Install the left wheelhouse liner.
   
5. Lower the vehicle.
   
6. Fill the cooling system.
   
7. Inspect all sealing surfaces for leaks after starting the engine.

Hope helps (remember to rating this answer).

The fuel filter on my 2004 Colorado is located in front of the fuel tank just behind the divers side of the vehicle. It is inside of a plastic support and is not easy to see.

Hope this helps.

On my 2004, there was a recal for a defective harness. You might want to see if there was a recal for the 2005. The resistor is located on the passenger side below the and behind the dash mounted to the air duct.

hi its situsted next to front passanger wheel in line with the transaxle you will see the oil pan the drain plug is on the back please rate this answer

engine compartment

Try servicing your engine. It might need a tune-up or a change of oil.