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Discussion Starter · #1 ·
I just finished changing the coolant on my 2011 5.3. Only took me 8 hours! First time.

Here's what I did; is this correct?
1. I drained the coolant from the bottom hose, but I used the end that attaches to the engine, not the end that attaches to the radiator. It was easier to get on and off.

2. I filled the system with hose water and drove it with the heater on. I let it cool, then drained it. I disconnected the top hose at the radiator and the bottom hose from the engine and used the garden hose to flush out the radiator. The water was clear.

3. I filled the system with distilled water. I used 2 gallons and the system was full. I drove it with the heater on, let it cool, then drained it. I repeated this step. Water was very, very light orange.

4. I filled it with Dexcool. I bought the premixed 50/50. I used a little less than 2 gallons. I thought the system takes about 4 gallons?

5. I will check the coolant after the truck sits overnight and cools all the way down and see if it needs more.

My original help post is here, but I thought I'd start a new one since the other one was getting kinda long.

coolant flush

Thanks!
 

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Well yes and no. Yes when you emptied the radiator for last time you will only get 2 gallons put back in. The system holds 16.9 quarts or basically 4 gallons plus a little under a quart. When you drain the radiator that's half of the system. So you will only get 2 gallons put back in.

I don't want to say it but I have to.. Using the premix you only have 1/2 the coolant you need. I'm sorry to say that If you were to use full strength then it would be 50/50.
I know you don't want to hear it but it is what it is. Been there done that and I know it sucks.
 

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Sounds almost exactly how my flush turned out. After I drained it the last time and started to refill it got full after about 2 gallons of (straight) Dexcool, thought oh crap it might be to diluted but I checked it and it showed good to -40 F so it must have been enough...

Basically you have about half of the water left in your engine/heater core and then you just added 25% more water and 25% Dexcool. I don't think you're going to have very good protection with that much water to Dexcool ratio. You may not be in danger of freezing but the coolant has other protective properties, rust inhibitors, etc that are really diluted for you right now so it may be worth to drain again and use concentrated Dexcool.

Premix is just a scam anyway. Buy the full concentrate of antifreeze and mix with your own water. It's usually cheaper as well, as far as what you get.
 

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Discussion Starter · #6 ·
I think I'm missing something. The owner's manual states that I need to put in Dexcool and water in a 50/50 ratio. I'm assuming the coolant in the engine was that same ratio, so anything left that wasn't flushed is probably close to 50/50.

I had about 5 gallons of liquid when I was done with the first 2 of 3 flushes. The 1st flush was about 2+ gallons and so was the 2nd. The last flush was mostly water.

I bought the premixed because it was on sale and cheaper than the 100% Dexcool. I have really hard water and thought it was a better option then adding hard water to my engine and letting it circulate in there for 5 years.

I also thought putting in just water then running the engine, draining it, then repeating a few times would flush all the coolant out. I only put in about 2 gallons each time, which I thought was odd.

I wanted to avoid removing the thermostat, even though the Haynes manual states to do so.

Should I use a vacuum pump to get ALL the coolant/water out? Do I have to re-do this?

Sorry if these are "stupid" questions, but I want to make sure I'm understanding you all correctly.
 

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I don't know what kind of climate you live in but if it gets very cold you are probably not protected from freeze up. When you initially drained your radiator you only drained about half the total coolant volume in the system. You then stated you added plain water to refill the radiator and drove it until warm. You then drained it again and repeated with plain water again. Bottom line is after your last drain of the radiator before the antifreeze fill you had about 2 gallons of plain water left in the engine block. So when you added 2 gallons of 50/50 mix of Dexcool to the 2 gallons of plain water in the engine block you end up with the total coolant mixture of about 75/25. Meaning 75% water and 25% antifreeze. You could drain your radiator and refill it with a 50/50 mix which would mean you would end up with something greater than the recommended ratio of water to antifreeze but probably ok. Or you could start over and do what you did originally but when you finally fill with antifreeze use 2 gallons of 100% Dexcool (not 50/50 mix).

I don't know where you buy your antifreeze but usually buying the concentrate is less expensive than buying the premixed. Keep in mind one gallon of concentrate gives you 2 gallons of coolant after mixing with water. And as far as the quality of water you have to use to mix with I always pickup a gallon of distilled water at the grocery store for about $1.50 which when mixed with your one gallon of concentrate equals - surprise- two gallons of coolant. Distilled water is far better to put into your engine coolant system than any ordinary tap water.
 

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I meant to add that if you live in a climate where freezing is not a big issue and you choose to leave it the way it is you will still be short on the recommended anti-boil and anti-corrosion protection and reduction of the lubricating properties (water pump) the antifreeze provides.
 

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silentbravo said:
Sounds almost exactly how my flush turned out. After I drained it the last time and started to refill it got full after about 2 gallons of (straight) Dexcool, thought oh crap it might be to diluted but I checked it and it showed good to -40 F so it must have been enough...

Basically you have about half of the water left in your engine/heater core and then you just added 25% more water and 25% Dexcool. I don't think you're going to have very good protection with that much water to Dexcool ratio. You may not be in danger of freezing but the coolant has other protective properties, rust inhibitors, etc that are really diluted for you right now so it may be worth to drain again and use concentrated Dexcool.

Premix is just a scam anyway. Buy the full concentrate of antifreeze and mix with your own water. It's usually cheaper as well, as far as what you get.
Good point but many people have bad water full of minerals which is a enemy to cooling systems, buy and use distilled water.
 

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Discussion Starter · #10 ·
Ok, so I understand why the ratio of water and coolant isn't 50/50. Took me awhile, but it "clicked" after I read the posts and thought about it. Bottom line is I have diluted coolant.

I want to do this right. How do I get ALL the coolant out of the engine? Suction pump? Shop vac? The Haynes manual states there are drain plugs on the engine block. I found one. Does this work?

At the very least, it seems like I need to drain some coolant and add 100% Dexcool.

I live in LA, by the way. It does get cold in the evening in winter and really hot in summer.
 

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If you want to start over read the link below but unhook the hoses like you did instead of the way I did. It would be easier for you. Start the flushing with a garden hose but end the flushing with distilled water. No need to drive the truck while doing any of this. It will take a couple of hours just because of the cooling cycles. Read it thoroughly so you will understand the procedure. You will need 4 gallons distilled water and 2 gallons full strength antifreeze. Do not mix. Do not mix. Do not mix.
2009 Silverado 100k Coolant Flush
 

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Discussion Starter · #12 ·
Gozzie: thanks for all your help and input. Thanks to everyone else, too!

I've decided to just drain some coolant and add some pure Dexcool to bring the mixture up to the proper 50/50. I calculated that if I drain 1.33 gallons from the 75/25 water/Dexcool mix in the truck, then add 1.33 gallons of 100% Dexcool, I'll bring the coolant to the proper ratio.

My goal was to get rid of the old coolant and it appears I did that. I just didn't get all the distilled water out when I flushed it, so when I added the 50/50 to the water already in there, it didn't result in the proper mix. My solution above will fix that.
 
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