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Where is The Thermostat on Chevrolet Trailblazer

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32 Responses

  1. Furqan says:

    Hi….my car got heat up on a highway and the mechanic told me to remove the thermostat without replacing the whole unit as there is no new unit available at him or nearby. HE told me that it wont effect anything.I had no other option as i had to go further on that road. Is it real urgent that i replace the whole unit as soon as i reach any city.

  2. Erica says:

    I just replace the water pump on a 2005 Chevy Trailblazer and but it still overheating I want to know do I need to replace the thermostat

  3. jennifer says:

    i just changed my thermostat my self last saturday and now my temp gauge is saying the truck is running at 212 but actually running at 204 by the computer. the only thing is im not running hot. all the fluids are full no leaks or cracks. what could be the issue? im also thinking about changing the coolant temp sensor as well. any help PLEASE im supposed to be driving to south flordia for christmas and dont want to get stuck

  4. Chubbo1965 says:

    WE just changed the Thermostat on my 2055 Chevy trailblazer 6L 4.2 its on the right side behind
    the alternator.

  5. Capt.Bill says:

    I am having over heat problems but h20 seems to be moving when thermostat opens. I look underneath engine and all is dry, no fluid on ground, but in the rear of blazer out of what looks like A C pipe there is water gatering on a sheet metal cross member. Does engine coolant run thru A C pipes or ?

  6. Kedar says:

    Thanks pal for the reply..Sorry it took so long for this ,thanks the the TCCM Is on the Left side on top of the Heater vent on left side , i had to remove the 4 lower bolts and 2 bolts that held up the left Heater vent and was right there..Man i wedonr why they put such a part in this place ;} ??wish it was on the fire wall like other yr models Ughh any way thanks anyway..

  7. marty says:

    I just completed the thermostat installation. Had to move the alternator though to get the top bold out.
    It was just too close to get in with the extension. Moving the alternator made it a lot easier to install the therm. housing
    and hose. It was a lot of work to get it done. But I’m glad I was able to do it.
    Thanks again for that good info.

  8. marty says:

    It’s about time somebody knows what they’re talking about. Thanks for the info.
    I have a 2003 TB and there is a lot of bad info on some sites.

  9. jtb1977 says:

    Damn I wish I had seen this article before killing myself for THREE HOURS taking that stupid thing off on the passenger side!!! I was told by a “mechanic” that thats where it was…lol. thanks fir the great info!!

  10. leonard says:

    i have a dtc 0f po128 07 tiail blazer

  11. gladys says:

    i was putting a thermostat for a 1999 oldsmobile alero.and now i cant get the bolts to go all the way back in the housing cover where the thermostat go.help!

  12. felix says:

    thank you,almost starting replacing the thermostat on the passenger side!

    • Anonymous says:

      how did you get to the bottom bolt to change out the thermostat that is on the passenger side of an 04 chevy trailblazer?

  13. Sammy says:

    Use a universal joint or even better a wobble end extension. That will give you enough angle to get that bolt to remove the thermostat housing.

  14. needAbeer says:

    so I tried goig through the wheel well (had to buy an extension) but the top bolt is behind the alternator, how did others get to that bolt?

  15. acdelco tech Lk.Limo Tavares,Florida says:

    Nice article and clarification on 4.2L I6 Trlblzr,GMC,Envoy;Several emails & mechs. have put articles for DIYs out there w/incorrect info…its not one text book proceedure fits all..appreciate those of us actually work on these vehicles putting accurate articles with pixs or diagrams as yours…keep em running brother!!!

  16. In a jam says:

    What tools do I need to replace my thermostat on a 2005 trailblazer trying to do it my self and any of you guy have a problem with a number 5 cylinder miss I replace spark plug,coil pack and rubber boot or spark plug wire and it still missing help

    • Frankie says:

      You just need a 10mm socket on a long extension and jhose clamp pliers. Get to the bolts through the drivers side wheel well opening.

  17. Wink1216 says:

    Changed thermostat today . What a Mother %$%%$$ to get to! also changed belt while alt. was off thanks for the help. Peace out and Merry Christmas !

    • Norshamila says:

      This sounds like the the radiator may have had an air pocket and needs the coolant topped off. Also may need to replace the tiadaror cap as the system needs to be able to build pressure. Worse cause would be a blown head gasket but you would notice a loss of coolant in the tiadaror.

  18. Wink1216 says:

    Quote 04 GMC envoy 4.2L can you tell me where is can find coolant below temperature sensor.

    There is no such sensor. I am guessing that you have a
    check engine light with code P0128- coolant temp below
    thermostat regulating temperature. This code is cause by
    either low coolant level, or more likely- a bad thermostat.

    • Phil says:

      Yes. If you read the sentence of the page your just posted, it says- where can I find the “Coolant Below Temperature Sensor”. There is no sensor called that. There is however a “Coolant Temperature Sensor”.

  19. Wink1216 says:

    the link that brought me here says there is no coolant temp. sensor see thermostat

  20. Wink1216 says:

    If what you are saying is true and that the vortec inline 6 has no coolant temp. sensor then why does auto zone sell one ?Duralast/Coolant Temperature Sensor
    For your 2004 GMC Truck Envoy 4WD 4.2L SFI DOHC 6cyl
    Price: $29.99
    Please help before i spend my money

  21. Anonymous says:

    Sorry to say but my 2004 has the thermostat located on passenger side of block near power sterring pump. Trying to figure out how to get out and find right part.

    • Phil says:

      That’s where I thought it was located too. Let me know how it goes and how to replace it. A picture of the thermostat when you do it would be great too !

    • Rob says:

      That’s not the thermostat housing, just the inlet for the upper house. On all Trailblazers and Envoys with the I6 is located on the drivers side, low and behind the alternator.

  22. Lissa says:

    You’re the graetset! JMHO

  23. butch says:

    Great pictures Protech. I read on forums all the time people saying the thermostat is in the upper radiator hose- which it is not. Maybe now they will see this article and put the argument to rest ! That part is hard to replace. Antifreeze gets all over the place and one of the bolts is a a pain to remove.