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Discussion Starter · #1 ·
Hey Guys,

I've been searching this forum for info regarding a tstat replacement and I have only seen info on the 3.9L engines.

Is my thermostat on the lower radiator hose on my 3.5L just like the 3.9L? YouTube also only shows the 3.9L swaps.

As far as I can tell, what I need to do is remove the lower radiator hose by loosening the clamp, pull the radiator hose, use a 10mm to remove the 2 bolts, pull the tstat out of the housing, replace with new unit (oriented the same way as the old), put the housing back on, bolt in place, and reattach hose and clamp.

Then I need to refill the system with Dexcool. I would place a funnel in the radiator and fill the system as much as I can while it's cold with some overflow.

Then I'd turn the engine on with the heat on max and the fan on low to make sure the heater core fills with fluid.

Once the engine reaches operating temperature the tstat will open and the extra Dexcool in the funnel will drop down into the engine and I can continue filling the rest of the Dexcool in the system.

At this point I can jack the car up on the side that the radiator cap is on, squeeze the radiator hoses to move air bubbles around and allow for the engine to vent the bubbles as much as it can.

(Correct me if I'm wrong, but I don't think I have a bleed valve...?)

Once the engine has been on for a while and the fan has kicked on twice then I can consider the job done.

Am I missing anything here guys?

I tried to be thorough before posting here.

Thanks!

Mike
 

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Sounds like you have it about right. Make sure when you get your new thermostat that you also get a spare rubber gasket for it. They can be a bit of a challenge to get back in without messing them up. The spare gasket is cheap and its one of those things that if you have it you wont need it but if you don't you will.
I used some silicone grease on mine to "coax" it back into where it lives.

Might look at getting one of these too.
Lisle 24680 - Spill-Free? Funnel | O'Reilly Auto Parts

You can run the car up to temp with the cap off and allow the air to bleed out without it puking out antifreeze while its doing it. They work really well and a handy thing to have for any other auto projects that include cooling system work. Just remember when you pouring the antifreeze in to pour it in slowly.

This is a picture of an 08 but I would think it's the same as the 09. ( I could be wrong though, I seen it happen ) .
It would be the same procedure as the 3.9.
I did mine a while ago and it really wasnt that bad to do.

https://static.cargurus.com/images/site/2015/10/13/01/47/pic-1530315826314110101-1600x1200.png

Let us know how you made out and by the way

Welcome to the forum
 

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Discussion Starter · #3 ·
Hi Pauly,

Thanks for the response.

Things went pretty well. I tried to buy that funnel and oddly it was hard to find on the day I was doing the swap.

It made it really hard to get the system to burp coolant because it kept over flowing, and I couldn't modify the funnel I had to not leak, so that funnel would have been a nice tool to have.

Otherwise, the tstat was exactly where I expected it on the bottom radiator hose (despite what the GM parts dept told me where it was [drivers side under the engine plate cover]).

I'd definitely suggest that funnel.

I'll be buying one soon.

Oh, and make sure to burp the heater core too.

Thanks again.
 

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Glad it went well...................kinda
 

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Yep.
I think there is a picture on here of mine when I did it and it looks exactly the same.
 
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