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Discussion Starter · #1 ·
I recently decided to flush the coolant system on my 1995 Chevy Astro van. I ran a chemical flush through the engine/radiator for a couple days and have been draining and refilling with distilled water for the last week or so. The water is getting cleaner, but I am only getting about 3/4 of a gallon out of the radiator each time I drain it. The owners manual states a capacity of 16 quarts so how do I get the rest out? How can I achieve a 50/50 antifreeze mix if I can only drain less than 1/4 of the fluid at a time?

My van has rear AC. I have been draining coolant via the plug on the radiator on the passenger side of the van.
 

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Discussion Starter · #3 ·
On each side of the block there is a drain plug. Take them out poke a coat hanger in there to knock the crap out.
Ah I see, that makes a lot more sense. I assume I should use some thread sealer or something when I put those plugs back in? Do they need to be torqued to spec?
 

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Ah I see, that makes a lot more sense. I assume I should use some thread sealer or something when I put those plugs back in? Do they need to be torqued to spec?
No they are a pipe thread no sealer. Wouldnt hurt if you want to tho. I don't know the spec I go by good-n-tight
 

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best way to fully clean the coolant system: after its empty add i cup of cascade dish washer powder to a gallon jug fill it with warm water shake it dump into closed system then fill with water. let it run for about 45 minutes with heater/s on full.
Then drain it as fully as possible and run a hose in it with engine running to allow it to clean it out. Then drain and refill with 50/50. But do not fill with tap water use distilled water. Tap water has minerals in it thet will clog the system.
 

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Also, you don't really have to drain the system to get a proper mixture. Every time you drain some diluted antifreeze and add 100% to it, you will increase the percentage of antifreeze to water.

You can pick up a mini tester for like $1.25 to see what level of protection you are at. https://www.walmart.com/ip/Chaslyn-Small-Anti-Freeze-Tester/16927981
 

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Also, you don't really have to drain the system to get a proper mixture. Every time you drain some diluted antifreeze and add 100% to it, you will increase the percentage of antifreeze to water.
Exactly. Personally, I don't get OBSESSED with this stuff. It's just not worth the extra trouble. After fully flushing a system with water... I drain what comes out naturally, add a gallon of antifreeze, and if there's any room left, finish topping it off with distilled water. I know it's fairly close to a 50/50 mix. Close enough for me.
 

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Discussion Starter · #8 ·
Also, you don't really have to drain the system to get a proper mixture. Every time you drain some diluted antifreeze and add 100% to it, you will increase the percentage of antifreeze to water.

You can pick up a mini tester for like $1.25 to see what level of protection you are at. https://www.walmart.com/ip/Chaslyn-Small-Anti-Freeze-Tester/16927981
Wow that's really cool. I figured I would have to drain the whole system to be able to know I had a 50/50 mix. Definitely gonna pick one of those up, very cool little tool to have.
 

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Discussion Starter · #9 ·
Exactly. Personally, I don't get OBSESSED with this stuff. It's just not worth the extra trouble. After fully flushing a system with water... I drain what comes out naturally, add a gallon of antifreeze, and if there's any room left, finish topping it off with distilled water. I know it's fairly close to a 50/50 mix. Close enough for me.
That makes sense. I just did almost all the other fluids and am pretty green when it comes to working on cars so I wanted to make sure I could do it right. Plus I use this van for road trips and don't want my coolant to freeze in the lines overnight somewhere because I got the mix wrong.
 
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