Thermostat replace without removing crossover
 

Hey guys,
I have to do a coolant flush in my wife's 3.4 2005 Impala. Same engine set up as our Alero's. While doing it I am going to replace the thermostat cuz god only knows how long it's been in the engine for the last 160,000 miles.

Is there an easier way to change the thermostat? I did the one on my 3.4 Alero but I did it when I did my LIMG. Everything I have seen says you have to remove the exhaust crossover. Is there a way around doing that? I'm not scared to remove it, I just don't feel like breaking exhaust bolts.

I should also add I'm doing this as regular maintenance and the fact that the Dex-Cool in it is original and turning to sludge.

No...you do not need to remove the cross-over pipe to change the T-stat. The right side bolt hole on the T-stat housing is slotted so technically you don't have to remove that bolt entirely. It may help to remove the throttle body for better access to the T-stat housing bolts. I've done it without removing the T-body however you'll have to clamp open the spring loaded throttle plate in order to get tool access to the T-stat housing bolts. You'll need some decent wrenches, curved ones are even better. Expect to turn the bolts only 1/4-1/2 turn each time which is a slow process but patience is the key.

Regarding the Dexcool...I no longer use that in my GA and just use regular anti-freeze like many others have done without issues so you don't have to use the Dexcool. Just make sure you flush out the cooling system really well and there are engine block drain bolts on each side of the engine which is the bolt just to the right of the knock sensor "A" in this photo.

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Cool. Thanks for the help man. I have big hands so I will probably remove the throttle body. It could probably use a cleaning anyway. Going to flush out the heater core too. Anyone know how many gallons the cooling system holds?

I generally do my own 50/50 mix with water on a fresh full refill...so one gallon of the Prestone concentrate gives me 2-gallons of mixed antifreeze which is more than enough plus some extra left over for topping off as needed. You are supposed to only use distilled water for the cooling system but I have a reverse osmosis water treatment system which is fine for me...so you'd need one gallon of the concentrate and one gallon of distilled water to yield two gallons of 50/50 mix. You can also buy the 50/50 premixed which I sometimes do for topping off or partial drain refills but it's a bit more expensive.

If the heater core hoses connecting to the engine side metal coolant tubes still have the plastic quick connects present then you might want to remove those while you're in there because they're prone to get brittle from heat over time and eventually leak..ask me how I know. :lol: They are used for ease of assembly during vehicle manufacturing and are otherwise not required. I replaced the heater core rubber hoses with new ones from NAPA and they were plenty long enough to reach with the plastic quick connects removed. Something else you might also want to think about @ 160K is replacing all of the rubber cooling system hoses if they are known originals.

They are original with the exception of the bypass hose and the coolant pipe hoses under the throttle body. I will replace the upper and lower radiator hose.

Well i went on Rockauto.com today and ordered the parts. All Gates brand. Upper and lower radiator hoses. 195* thermostat. Belt tensioner....makes noise. I also picked up a Wix oil and fuel filter cuz it's time for both of those and being I am doing it at school and have access to the hoist I figured good time to change both.

Good idea to replace the quick disconnects. Mine broke in the AutoZone parking lot (thankfully they had replacements in stock).
The rest of the time, you won't have the luxury of those waiting to break in a convenient place like that.

I still have my original plastic ones (assuming that's what came with a 99 V6). Isn't there a metal (brass), presumably aftermarket option?

How do you replace the quick disconnects? Could I just get did of them?

in 03' the had a different system than with the early aleros, I believe it was another thing they changed in 01'

I got rid of them entirely on my '99 and connected the heater core hoses directly to the metal coolant pipes on the engine side with hose clamps...it's been like that for almost two years now without issue.

Cool that's what I was wondering. My wife's Impala's engine bay is almost identical to my Alero so it's got the same quick disconnect system. I will just delete the quick disconnects if they look brittle or bad.

There probably is a metal replacement, I just went with the quickest option.

You can make your own replacements with a barb. That's what I did but I have the redhead 60 degree and I deleted it from the LIM to heater hose.

I got 4 gallons of 50/50 dexcool to use after the flush. Going to flush the radiator repeatedly. I am also going to flush the block until the water comes out clean of the lower radiator hose. Then I am going to flush everything out the block drains. Scrubbing all the crap out of the overflow tank as well. After it's all done I change out the thermostat, upper and lower radiator hoses, heater hoses as well. Already did the ones on the bypass pipe. Water pump should be ok as it only has 20,000 miles on it.

Car never had a cooling issue. So not worried about that. The dexcool just has 160,000 on it and never been changed.

Changing out the belt tensioner as well. Taking a road trip from Nebraska to Michigan next month and wanna be prepared

Take out the thermostat first so the water flows, otherwise you'll have to wait until the thermostat opens.

I planned on taking the thermostat out first. That's the main reason I am replacing it cuz right now it works just fine. I just thought sense it's hard to get to and I'm going through the trouble of taking it out that I'm going to replace it.

If the water pump is the original then @160K I'd replace that as well. Don't run the engine too long with just water cooling because doing so isn't good for the water pump bearings since the coolant also serves as a lubricant. Now if you do decide to replace the water pump then leave the old one installed during the water flush if you plan to run the engine.

Water pump, to my knowledge, was replaced around 130k. She had it done before I met her. So I don't plan on changing it. I am going to flush the engine without running it hopefully. If I end up changing the water pump it's no big deal because they are cheap.