# Draining, Flushing and refilling a radiator



## crankbait09 (Mar 26, 2011)

Hey all

I have a 2002 Chevy S-10. I purchased the truck brand new in 2002 and I have NEVER had the radiator flushed, cleaned and refilled.

How often should the radiator be flushed, cleaned and refilled?

It seems pretty straight forward to do but wasn't sure when it should be done..........

I also notice that antifreeze needs to be diluted with a ratio of water when refilling. I also have noticed that the antifreeze they sell nowadays is already diluted with a water ratio, so no need to mix yourself........can anyone also confirm this?

Thanks for your help


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## rusty baker (Feb 13, 2009)

That pre-diluted antifreeze has some expensive water in it. If you drain the radiator every couple years, there is no need to flush it. You can't flush the block without equipment most DIYers don't have anyway.


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## Rehabber (Dec 29, 2005)

If you are flushing the cooling system, drain and refill with deionized or distilled water, run engine with heater on, redrain and refill with coolant. Full strength coolant is cheaper than 50/50, just mix full strength with DI or distilled water to get a 50/50 mix.


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## DoctorWho (Jun 21, 2011)

Trust me, stick with the 50/50 premixed stuff, can't go wrong and you don't have to sit there and measure to make sure you're mixed right, totally worth the extra cost.
As far as how to change the fluid it depends of whether you just want to get "most of the fluid" or "all of the fluid". Just flushing the radiator will get most of it, to get all of it you'd have to run the engine with water in the radiator and even then you'll never get ALL the old coolant out, plus you just made all the fluid inside the heater and engine mostly water, so even if you add a 50/50 mix you'll end up with a higher ratio of water once it all mixes together.
What I've always done is just pop off the lower radiator hose, drain out as much as you can (squeeze all the hoses, heater hoses etc), then just fill her up with a 50/50 mix and then run and recheck until all the air bubbles work their way out, they like to get caught in the heater core so make sure your heater works well before you decide your done. If your truck has a radiator cap on the radiator itself run with it open to let air escape, can't do that on my ranger since there's no cap, just the overflow bottle.
Doing that will have gotten the majority of the fluid refreshed and will do just fine. Also in my experience the cheapo coolant is just as good as the name brand stuff, it all has to meet minimum guidelines and I think most exceed them anyway.

Almost forgot, as far as when you're "supposed" to change it? It varies from one manufacturer to another, my Kia says to do it every 30k miles which is way more than necessary, some cars I believe don't specify it's needed until 100k miles and then like every 30k after that or something like that, if you still have your maintenance guide it might say in there.


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## rusty baker (Feb 13, 2009)

You can't flush the block unless you take out the thermostat. Too hard for many DIYers. ........A lot cheaper to keep one of the old antifreeze jugs and premix your own. Besides, it doesn't have to be a perfect 50/50 mix.


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## Marty1Mc (Mar 19, 2011)

^Agreed. I buy a gallon of anti-freeze(around $12-13), and a gallon of distilled water at Walmart for under $1 (last time was $.58). I pour half a gallon of anti-freeze in the radiator and follow with a half gallon of water. I then pour the remaining 1/2 gal of water into the anti-freeze bottle, mark it 50/50 and use it to top off the system.


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## polarzak (Dec 1, 2008)

DoctorWho said:


> Trust me, stick with the 50/50 premixed stuff, can't go wrong and you don't have to sit there and measure to make sure you're mixed right, totally worth the extra cost.


Kinda goes against the whole DYI concept. If one cannot mix their own antifreeze, they are just wasting money buying the premixed.


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