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Heater Core Flush (No Heat Fix)

21K views 27 replies 13 participants last post by  Rhotpursuit 
#1 ·
If your heater blows cold air, your engine is getting up to temp, and all your switches and actuators are working properly this is your problem....

For reference this is being performed on a 2000 S10 Blazer 2dr 4.3vin W w/AC

Basically GM uses dexcool, when neglected or after becoming too diluted with water over a long period of time it likes to turn into a nice brown sludge of a substance that clogs up your heater core and everything else in your cooling system. Im going to show you how to flush the heater core out with some simple items you can buy at your local parts store.

List:

-5/8in. Garden hose I used a 50 footer that they had at O'Riely's for $9.99
-Adapter's for your heater hoses (on mine one side was 5/8 already and the other was 3/4 so I bought a 5/8-3/4 adapter) $2.99
-Section of hose to mate the adapter to the heater core (in my case 1 ft. 3/4 heater hose) $1.99
-Optional screw type hose clamps (I bought them and didnt use them alot of people dont line the spring type clamps I have a special set of pliers that takes them off so I like them, up to you) $1.99



Heres a picture of everything I used.




Next youll remove the two heater hoses from the firewall that youll see in the above picture.




Then youll attach the end of the garden hose attached to the spicket onto the drivers side heater core tube. Of course the adapter, 3/4 hose, and other length of garden hose which should go into some container an old garbage can or something to catch the mess thats soon to flow out of that end of the hose. Then you turn the spicket on really low at first until you fill the heater core up and water starts to drip out of the end of the drain hose. Once you have a steady flow coming out of the hose turn it up a bit at a time until your at good flowing flush rate that your comfortable with I didnt go too strong at fear of over pressurizing the heater core and blowing it up all over my passenger side floormat. When I was done I reversed the garden hose ends and flushed it in reverse or backflushed it just for good measure.

Thats it my truck is nothing short of hot inside in washington state 28 degree weather and it did not work one bit I could swear the A/C was warmer prior to flushing. Good luck hope it helps.

:flame::cool:
 
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#3 ·
Re: Ready For Edit: Heater Core Flush (No Heat Fix)

Thanks, yeah I could have I dont think I coulda shoved a 5/8 hose on a 3/4 without ruining it though so I still would have had to bought everything minus the garden hose and I wanted to see all the shit that came out of it lol.
 
#4 ·
Re: Ready For Edit: Heater Core Flush (No Heat Fix)

yep, gotcha ya....i guess i'll have to flush my system too after winter...or maybe just replace the heater core altogether...i do have a replacement already just didnt get to it before winter got here...so i took the quick and easy way out this time...
 
#6 ·
Re: Ready For Edit: Heater Core Flush (No Heat Fix)

My '86 had that exact problem after years of cooling system neglect.( the prevous owner, not me). Tried the flush and fill kit and hosing out everythng and all was good except the heater core. I already had t's in both the core inlet and outlet hoses ( again previous owner) so i removed both hoses to the core and used one of the old style garden hose nozzles that twist on and offf. Since its tapered i just shoved it in one hose and blew the crap out the other and switched back and forth till the core ran clean. heat works great now
 
#9 ·
Re: Ready For Edit: Heater Core Flush (No Heat Fix)

Or you could just not be poor & replace the fucking heater core, flush the dexcool and fill with regular antifreeze..
Im not going to argue with you but really? Not be poor? Its a little radiator that cost 60 bucks gets full of shit and you can easily flush out the completely functional part that has absolutely no reason to be replaced for 15 bucks and save yourself at least 12 hours of tearing apart dashes? Common fucking sense my friend.

Why dont you just buy new rims with new tires on them already when the tread wears out on your old ones? Dont be poor... :phil:
 
#10 ·
Re: Ready For Edit: Heater Core Flush (No Heat Fix)

Or you could just not be poor & replace the fucking heater core, flush the dexcool and fill with regular antifreeze..
Replacing a heater core is a PITA though. If flushing the junk out of your existing core buys another couple of years before you need to do it then it's worth it IMO.

Even if you have the money to replace the part, why not maintain the one you've got and get the max life out of it on principle?
 
#12 ·
Re: Ready For Edit: Heater Core Flush (No Heat Fix)

You sir have...

Diarrhea of the Mouth
-The opening through which an animal or human takes in food develops a disorder characterized by abnormal frequency and fluidity of fecal evacuations.

Throwing a functional part away because it needs some water run through it is illogical nonsense.
 
#15 ·
Re: Ready For Edit: Heater Core Flush (No Heat Fix)

"Why dont you just buy new rims with new tires on them already when the tread wears out on your old ones? Dont be poor..." LOL!

And for those hating, sorry you guys have all this money floating around. You know some of us need to work hard for money and would love to save some money if we can, why replace something that isn't broken if you can fix it for 1/3 the cost? Awesome post Rhygin Thanks!
 
#18 ·
Re: Ready For Edit: Heater Core Flush (No Heat Fix)

What are you guys 12 lol? This is good helpful information to be soiled and thread jacked for someone's inherent need to start shit because they have nothing better to do... Just how much useless bickering have you caused with 20k post in 3.5 years?
 
#20 ·
Re: Ready For Edit: Heater Core Flush (No Heat Fix)

nice write up :D most people will read this and see wiw and thank you for it.
 
#22 ·
Re: Ready For Edit: Heater Core Flush (No Heat Fix)

And for the record. I have used this method in the past on a Ranger, a blazer, and a mustang and they always end up clogging again. that's why I personally suggested to replace the entire core. Just having some fun while expressing my opinion.
 
#24 ·
Re: Ready For Edit: Heater Core Flush (No Heat Fix)

Why not do it right the first time?
Flushing it out for free Vs. buying a new heater core.

My old blazer had this exact problem and I just flushed the system out and put a new thermostat in and it worked for a year before I sold it. I don't know about you, but I don't like spending money unless I have to, so fixing a problem for free don't come often.:cool:
 
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