Thermostat Replacement Thoughts (03 Envoy) - Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum

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Old 01-14-2013, 10:18 AM
gstump gstump is offline
Junior Member
2003 GMC Envoy SLT XL
Pewter Metallic 4.2L I6 AWD
Join Date: Jun 2007
Location: West Linn, OR
Posts: 43
Thermostat Replacement Thoughts (03 Envoy)

Not gonna do a "how to" here as there appear to be plenty (thanks!). Did wanna just post a few thoughts. Just did mine yesterday and my really low temps abd crappy gas mileage has returned to normal.

Comments (in order_:

-Removing lower radiator hose: If you can get at the hose clamp then you won't have to remove the cross beam. Unfortunately on mine the clamp release was turned around and I couldn't get at it and had to removed the entire cross beam to get to it. Extra time and 8 bolts later I was able to pinch the clamp, remove the hose and drain the coolant.

-Removing alt: This job is a PITA even with removing the alt. I have read that it can be done without removing it but I'd have to see it to believe it and would want to time you Maybe with a lift and a lot of light and my dads ultimate set of tools! Me I removed the alt. That damn black hoist bracket is the issue here. It has 3 bolts. The two facing the front are fine but the one facing the battery was biggest pain of this entire job. Countless hoses and tubing are in the way of getting a socket on it. I ended up bending the crap out of it to where I was finally able to get a wrench in there. When I got it off I chucked it out in the yard and swore I would not reinstall the POS (it's still in the yard). Don't try to unhook the wires to it until it's unbolted...those contacts are easier to get to when it's been rotated around.

-Removing driver side wheel: Doing this made things only slightly easier. You can look in there and see where stuff is and you can reach in a hand tighten/untighten the lower t-tat bolt which is nice but that's it.

That's about it. That single bracket bolt took the most time and effort so have a plan for that and the rest should go smoothly.
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Old 02-11-2013, 08:38 PM
Gevans17 Gevans17 is offline
2004 Chevy TrailBlazer LS
Dark Green Metallic 4.2L I6 2WD
Join Date: Nov 2006
Location: nawlins
Posts: 204
thermostat R & R

Having done this on both 2002 and 2004 TBs, I think the safest method is to remove the alternator. I think that going in thru the wheel well runs a huge risk of cross-threading and stripping the thermostat housing bolts.
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Old 02-13-2013, 08:13 PM
CarbonJoe CarbonJoe is offline
Junior Member
2003 GMC Envoy SLT XL
Pewter Metallic 4.2L I6 AWD
Join Date: Apr 2007
Location: NE Ohio
Posts: 57
I did mine through the wheel well with no issues. Just go slow when putting the bolts back in. Use about 18 - 20 inches of extensions and a universal. If you have to drain the coolant anyway, might as well do the water pump and temp sensor. Maybe new radiator hoses too.
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