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2005 chevy trailblazer_lt
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Discussion Starter · #1 · (Edited)
So I tackled the thermostat job today and I wanted to try and get it without messing with the alternator. I was able to do it, and it took between 1-1/2 to 2 hours(I had to run for a clamp, plus taking pictures) Plus I don't have a garage so running for tools took some time.

1st is jacking up the left side and removing the front tire, jack stands under frame.
I placed some pieces of cardboard around the differential and under the radiator to help filter the coolant into my pan. Next I removed the clamp from the bottom hose, I used a pair of big honkin' channel locks for this. Here is the hose

After pulling the hose back I pushed it up and let it sit out of the way. I then used a combination of long extensions to reach the bottom bolt and a 10mm socket:

I then used a universal socket to reach the top screw, from the opposite side of the spring;

You could let the screws fall, but I used an extendable magnet to pull them from the housing. Here is the socket

My gasket on the new thermostat was quite secure so I did not need any grease, so I was able to put the housing where it needed to be and fed the bolt into the hole. I used a small magnet inside the socket to hold the screw from falling out. I did the bottom screw first, and turned it just tight enough so that I could still push the housing with the extensions so I could line up the top hole. I the used the universal socket with the magnet to place the top screw in and started it by hand, then used the ratchet. The clamps from the factory are not fun in this tight space, so I replaced it with a screw style clamp.

You can see I have the factory clamp in the locked open position, getting it closed in there was tight, so again I used the universal socket to reach the screw on the new clamp. I removed the top hose to get fluid into the engine and radiator.
 

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2003 chevy trailblazer_ls
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I wish you had posted this three days ago. I just replaced mine and removed the alternator. :duh:
 

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2004 chevy trailblazer_ls_ext
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i replaced mine last year and i am already getting the p0128 code again. what brand stat did you get? i think might have the local mechanic do it again. he only charged $45 labor do replace it.
 

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2003 gmc envoy_slt
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After driving around with the P0128 code going on and off for almost two years now I finally decided to replace the thermostat this weekend. I was ready to pull the alternator based on other posts. But I'm sure glad I saw this first. The photos were a big help.

Everthing was going to plan until I got to the top bolt. I didn't have enough extensions to reach. The photos showed three, I only had two. So off to the hardware store.

Once I got back, I got the old stat out without a problem and started installing the new one. I could reach the top bolt to start it by hand and ended up dropping then bolt and loosing it. Another trip to the store!

I finally got it installed, refilled the anti-freeze and check for leaks. All looked good . It took 3 1/2 hours, including the two side trips. The check engine light went out after a couple short trips.

Thanks for the great info. This was definately easier than pulling the alternator (I probably would have been short tools for that job too).
 

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2004 chevy trailblazer_lt
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is it just me or are you body lifted and thats why you were able to fit the tools?
 

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2005 chevy trailblazer_lt
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Discussion Starter · #8 ·
I have big hands and I could get them in, though I had to go slow due to sharp edges. I did not try reaching all the way back with my hands. Using a magnet inside the socket worked well, as I hate dropping bolts, especially when you can't find them.
 

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2002 chevy trailblazer_ls
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Excellent information! :thx

One thing I would suggest is a ratcheting hose clamp plier tool which would have made dealing with the clamps a lot easier and super-easy to reuse. I bought one when I did my fan clutch.
 

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2003 gmc envoy_slt
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Why did you remove the top hose to refill the radiator? :confused:
 

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Discussion Starter · #11 ·
I just wanted to make sure I got as much fluid into the engine as possible to minimize any air pockets. One the fluid came to the top of the hose, I put it back on then filled up the radiator.
 

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Thanks to this thread I didn't have a problem except losing a bolt.:suicide: In the end I found it. Didn't have a magnet but instead used a piece of napkin to secure bolt in the socket. Just overlap piece of napkin over socket and then insert bolt till firmly secure. I did use a GM thermostat and code went away.
 

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Very very interesting.
Good to hear you were able to get to it this way.
I wonder if the factory leaves the compression clamp pointing in the same direction for all Trailvoys?
I too have used vise grips to remove that clamp--- but it was BARELY in the right position to use Vise Grips- Replacement clamp was the screw type like yours.
 

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How hard was it to slide the hose back on?
From changing the hoses on my Trailblazer-- I know that some can be a pain to slide back on- even whith plenty of room...
You have trouble considering you had minimal space?
 

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Discussion Starter · #15 ·
I actually slid the hose back on from the top. I was able to get a better grip that way. The clamp was in a decent spot, but had it been turned down 1 more inch, I would have been able to get it from the top with a regular pair of pliers.
 

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Good write up! This is one I am in need of doing myself, will get around to it sooner now that I know what is needed. Thanks!
 

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Agreed--- that if that clamp is in the right position- you may have the gods looking down at you... if not and its pointing in a diff direction- you must have made the gods mad.
 

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Done! SES light off and temperature is where it should be. Write up was great and worked perfectly. Thanks.
 

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2004 chevy trailblazer_ls
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GRRRRRR I am having the WORST luck with the process of changing my thermostat!

I started off with the though the wheel well way... but ran into issues so I then went on the the remove the alternator way... No luck there (couldn't get the darn bottom bolt off) so I went back in the wheel well. I was able to get both screws out once I figured out the right angles. So as I was putting the new one on I dropped a bolt... :duh: Grrr 1 hr later I gave up and went to autozone for another. I finally got both bolts installed good and tight and got the hose back on. When I started filling it I noticed I had a pretty steady drip coming from the middle of the thermostat! I think I got a defective one. :( :eek: So now I am in the process of removing the bolts again to return the darn thing to AZ and try again... of course now I am not able to remove the top bolt (too tight I guess). I've gave up for the night and will call in to work tomorrow and give it another shot.

:bonk::coffee:eek::hissy::duh::x

Oh and I accidentally broke my A/C pressure sensor so there goes another $60... GRR I hate cars! hahahahahahaha

Thanks for letting me vent.
 
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