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how-to flush heater core?

47K views 26 replies 13 participants last post by  draggnutz 
#1 ·
Just from reading on here, I need to flush my heater core. I have no leaks, but when I turn the heat on it feels like the a/c. Sometimes gets a little bit warm. I understand the process of flushing it out, I just need a pic of the two hoses I need to disconnect to do so. I have a 2002 chevy s10 with a 4.3 could anybody help me out?
 
#4 ·
if you dont want to buy that kit you can just take the hoses off the motor and use a water hose with a nozzle.had the same problem on my blazer did it that way and worked great.the core had a bunch of the dexcool mud in it.after that i flushed the whole system real good then replaced it with green antifreeze.
 
#5 ·
Thats exactly what I did and thats exactly what mine was like...mud...:(
Much beter after. That link was just for a pic and to give a good idea how its done. It dosent take long to do either. How many miles do you have? You may consider replacing your thermostate too. Dont have to but its a nice peace of mind knowing that its been replaced. :D
 
#6 ·
I have about 95,000 km (not sure what that works out to in miles) should I give it a good flush then do the whole cooling system?
 
#7 ·
sry about the double post but I was just driving for about a half hour, felt the 2 hoses and the one on the left was hot and the one on the right was cold so I'm sure this is my problem, gonna flush it tomorow, I'm sure it'll work mint
 
#8 ·
I was told by a dealership (1st problem:rolleyes: ) that some S-10s need to have it done and others may not....The ones that do usually need them done every year or 2 because they clog up....the ones that dont..dont. I did mine over a year ago and its still fine. I would just flush the heater core, replace your thermostate with a new one (same temp.) and call it good. You will be fine for a long time. No need to do a complete system flush unless you realy feel the need to.
 
#12 ·
flushed her out, I HAVE HEAT!!!!! Just in time for good old Canadian winter. Thanks for your help guys, think I'm gonna get the whole system done in a few weeks fromvwhat you guys are saying.. Thanks again guys
 
#13 ·
Glad you got it fixed. My wife had a 00 blazer, and it clogged up from the Dexcool (garbage). When my truck hit 100,000 miles I did some services to it like a new belt, new antifreeze, 02s etc. I will tell you though if you have a SES light come on soon, it is likely from the thermostat. Mine apparently stuck open after the antifreeze change because I noticed it running significantly cooler, and then came the light.

They're cheap, so i would suggest changing it. It's real easy on these trucks and less messy than a lot of other vehicles since you won't need any RTV.

-jk
 
#14 ·
Hello,
I've got to do the same thing, heater core is plugged after I got some work done at the dealership.
They flushed it once, but it's plugged up again just three days after.
I just want to ask how much pressure I can put on the core without blowing it up. Is normal City Water Pressure ok?
Also, is there any cleaning solution you'd recommend to add to the dexcool before swapping it out?

Thanks,
Tom
 
#15 ·
garden hose worked great for me! not too sure on a cleaner though
 
#16 ·
do you have a picture of what hoses? this is older thread so the pics were gone on that link, and im in need of this badly, might call tomorrow on how much a full system flush is though, but a cheap alternative would help for now. also i guess im going to change out the dexcool for the green stuff
 
#20 ·
i just did this last week. take the two hoses that are coming out of the fire wall.....follow them to where they connect to the motor. unclamp and remove the hoses FROM THE MOTOR, NOT THE FIREWALL. aim one down at the ground and insert a garden hose into the other. flush until water comes out clear. backflush it by doing the same thing to the other hose. boom, you're done. it took me maybe 30mins.
 
#23 ·
Now newb question. When you take the two heater core hoses off the engine will all the coolant come out? Also this just flushes out just heater core not the whole engine right? Is it a good idea to flush the whole system so it doesn't just replug? Thanks guys.
 
#25 ·
Did you use a back flush kit or did you do it some other way? Also if you hook the hose up to the cooling system do I need to worry about the pressure? I heard you have to watch the pressure when flushing the heater core or you can blow it.
 
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