Where is thermostat on 2004 gmc envoy 4.2L V6

It's in order, from the front of the motor to the firewall. #1 is nearest to the radiator, # 6 is at the firewall.

Answers 2&3 were right...under the left rear seat is a fuse box, pull the nylon webbing in the center of the fold between seat and seat back to release the latch...fuses 46 or 15 should be the ones you're looking for...

More than likely the thermostat is stuck open. You should replace the thermostat and the temp sensor. See picture below for location.

Please get a Coolant pressure test done which will expose the real leak.

I’m happy to assist further over the phone at https://www.6ya.com/expert/uttamjeet_2f3adc18600f8ede

On a 2004 GMC Envoy xl v6, the alternator has 3 mounting bolts, 2 on top, 1 on bottom. best advice is to disconnect the electrical circuits to the alternator first before removing the mounting bolts. then take off the bottom bolt, followed by the 2 on top. then just slide it out and your done.

Please see my tip at http://www.fixya.com/cars/r5929960-s_thermostat . These are generic instructions. If you get stuck or need specific instructions for your car, please get back to me with model, year and engine info.

On the 4.3L engine, the thermostat is on the intake manifold, whereas on the 5.3L engine it is at the end of the lower radiator hose where it connects to the waterpump.

4.3L

If you go to www.trailvoy.com and do a search on thermostat replacement, you will find a thread that details the process.

replacing thermostat in 2004 gmc envoy

well do you have the 4.2 or 5.3 motor 6cy or 8cy need to know and i can help

This an engine coolant temperature fault, most likely caused by a defective thermostat, probably one that is open all the time.