Chev Trailblazer thermostat replacement

[BrianF]

Just did the thermostat in the Tb today. Not that hard of a job if anyone ever needs to do it.... I have the I6 so it is a bit precarious but not overly hard. Remove the alternator with its third and hidden bottom bolt, bend and juggle the AC line out of the way and viola.. you get half [censored]ed access to it on the driver side of the block. Its held on with 2 10mm bolts one is easy to see and access while the bottom, rear most bolt is actually accessed with several extensions and through the wheel well. Once you pop the thermostat off you twist it up a bit to access the clamp for the hose and you remove it that way. Reverse order was much easier but make sure you clock the new thermostat on the hose correctly so that it lines up with block without much force. I used less than 7 liters of coolant to top up and it appears slightly less than required when I did the water pump some time ago. I pop the bottom rad hose off and drain as much as possible. Its a poor mans flush.

I used the ACDelco part, which is manufactured by Behr and got a decent price on Amazon.ca, much cheaper than the dealer wanted.

Last fall I noticed the dummy gauge was a tick cooler than its normal operating temp. My scanner showed I was topping out at 88C on sustained highway driving but I was not getting any temp codes so I knew I had a bit of time. Once the system was burped and a nice test drive, I was floating around 94 to 96C under load and it dipped to 89C briefly as it appeared the thermostat opened, then it slowly crept back up.

 

[Nick1994]

Yeah OEM is the way to go. My grandparent's had an 02' Trailblazer and the Stant replacement had quite a bit smaller opening than the OEM one.

 

[StevieC]

I always go with OEM thermostats. It seems there is a lot of aftermarket out there that are off by 5-10 degrees and that can have problematic effects on modern vehicles.

 

[BrianF]

That's exactly what I was hearing. Some makes don't last as long and others are off on the temp. If I got 200,000km on the oem stat then I think it would be wise not to deviate.

 

[edwardh1]

did it have a wiggle valve or pin in it

 

[Falcon_LS]

I always get the OE 15-11006 myself.

Not as easy as my Grand Marquis, but still not as bad as my SRX. I take my sweet time, thoroughly flushing out the system and usually get in about 3.5 gallons (13 liters) to fill it up. Always used Dex-Cool, but will be switching to John Deere CoolGard-II the next time I'm due.

The cooling system is reverse flow, usually my coolant temperature range is in 190ºF to 200ºF range during the cooler months of the year. In the summer, it usually tops out at 224ºF.

 

[gonefishin]

The '04 I-6 Trailblazer I have is driven by my youngest son. I did a thermostat replacement with a Gates brand back in July '09....almost 150,000 miles ago. It's still running great.

I had the known issue with this truck running a little hot in the summer with A/C on in traffic. The temperature gauge in these gives a fair depiction of the temperature and is close enough to give the driver some indication. It would creep over the 210 bar, maybe in the 220 range. This probably isn't enough to be an issue but I never liked it.

Earlier this year the radiator developed a leak and I replaced it with a Spectrum CU2458. What a difference. Now it rarely creeps past 210 in the hottest days in Dallas, in traffic with the A/C on. I guess over time the radiator collects dirt, etc. on the outside which can't be washed out with the best of attempts.

Rambling over....just thought I would share my experience.

 

[GMBoy]

That was the hard way.....I removed the left front tire and wheel liner. It's looking at you and easier to get.

 

[StevieC]

I would change the manufacturer and that way you don't have to go through all that trouble because they think about the mechanics having to repair these things.

 

[BrianF]

I had spied through the wheel well but opted to try the way I had read about first. As for a jiggle/wiggle valve, I am not familiar with the term and the thermostat looked about as standard as I have seen them.

I had it out on the highway today for a rip to town. Used the scanner and the temp was good all the way. It warmed up fast and held 90 and above the whole trip.

Also fixed the AIR solenoid. I had ripped the pump out last fall but left most of the piping in, with it still connected to the solenoid. I had developed a gurgling sound that I traced to the piping. Seems the solenoid was allowing air to be sucked in while the engine was running. The piping had moisture in it and would gurgle as the engine sucked air past it. I never checked my readouts but I surmise it was causing a lean condition. I made a block off plate from aluminum that I bolted between the solenoid and its exhaust port. Problem solved.

Also greased the driveshaft U joints and changed the TC fluid. I made another post as I decided to venture out from the AT2 fluid...

 

[4ever4d]

Originally Posted By: GMBoy
That was the hard way.....I removed the left front tire and wheel liner. It's looking at you and easier to get.

Yes!