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Discussion Starter · #1 ·
I am a 17 year old and this is my first vehicle. I have a 2002 S10 4.3. Problem is that no heat comes out of the heater. It blows, but no heat. I do not see a valve inline that controls flow into and out of the heater core. Where is this located? Anything else this could be?

Thanks in advance.
 

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check your coolant level there is not a valve that controls coolant flow through the heater core. have you had any issues with the truck running hot or any thing like that?
 

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Sold :'(
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There is no valve to make the coolant bypass the heater core when the heat is not selected on the A/C control panel. Although, I read somewhere about installing one from an Explorer to cure the "Hot Feet" syndrome these trucks are plagued with. Anyway, your heater core may be clogged. With the engine cool, disconnect the hose at the firewall that goes from the heater core connection to the intake manifold. Have someone start the engine while you watch for coolant to come out of the heater core tube.
 

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Heater core could be plugged/blocked. Had this problem last year with my Blazer. Pulled the hoses off and back flushed it with water and all was well until earlier this year when the heater core started leaking. Had to pull the dash and replace it.
 

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Heater core could be plugged/blocked. Had this problem last year with my Blazer. Pulled the hoses off and back flushed it with water and all was well until earlier this year when the heater core started leaking. Had to pull the dash and replace it.
This is a correct remedy, and likely your problem. It happens often and is caused by the DexCool Coolant...it turns to "goop" and blocks the flow of coolant in the heater core.
 

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Discussion Starter · #6 ·
Thanks guys, flushed the heater core, and it works great. Lots of black goo in there. Think I will flush the whole system soon.
 

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now that he has the answer he was looking for im gonna jump on the thread. I too have no heat I have checked my heater core (felt both lines and both were hot) however I do not have heat looking for a damper door or something. Good air flow just no heat. BTW its a 88 4x4 4.3 s-10
 

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If this is caused by DexCool, then what else should be used, or a better brand?
Many of us switch to the green stuff with no side effects...
 

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I used Prestone in the yellow jug that's compatible with all brands of coolant so it didn't cause jelling by mixing with any remaining Dexcool that wouldn't come out. Plus it's a couple bucks cheaper a gallon than Dexcool.
 

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motorking
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If this is caused by DexCool, then what else should be used, or a better brand?
Hi,
I am the Tech Manager for Prestone coolants. I have to tell you that dex-cool just gets a bad rap. GM still uses it, BMW, Mercedes and Ford/Chrysler are all going to it in 2011. The cooling system design in many GM's is not the greatest. To prevent the sludge you need to prevent air ingestion into the coling systme. that means no leaks, good cap and keeping the recovery bottle full to the line. That said, you should pull the lines off your heater core and back flush the heater core, bet your heater starts working. You can use Prestone Extended Life coolant as well. Good luck.
 

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raviolli
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maybe one of you kind fellas could run me through the steps of backflushing the heater core? my heat has been colder than most brand new cars AC. i live in florida so i only need heat about a month out of the year and since i never figured out what the problem was i just decided to suck it up and drive with gloves on
i know its the dexcool goop because my first winter with it my dad squeezed the heater core hoses and it loosened up and gave me about 2 or 3 days of heat. which was enough because it got hot again after that
but yeahh...im planning on moving to ohio by 2011 so itd be nice to have heat...
 

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Hi,
I am the Tech Manager for Prestone coolants. I have to tell you that dex-cool just gets a bad rap. GM still uses it, BMW, Mercedes and Ford/Chrysler are all going to it in 2011. The cooling system design in many GM's is not the greatest. To prevent the sludge you need to prevent air ingestion into the coling systme. that means no leaks, good cap and keeping the recovery bottle full to the line. That said, you should pull the lines off your heater core and back flush the heater core, bet your heater starts working. You can use Prestone Extended Life coolant as well. Good luck.
With all due respect... DexCool has caused so much grief for GM owners that unless your company does something drastic it's tarnished image will never be bright as it was when it was introduced. Dexcool is loathed and hated many tens of thousands of automotive mechanics and hobbyist. Add to that, other companys have introduced "compatible" green extended life coolants...DexCool is becoming a modern day "dinosaur"
 

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motorking
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With all due respect... DexCool has caused so much grief for GM owners that unless your company does something drastic it's tarnished image will never be bright as it was when it was introduced. Dexcool is loathed and hated many tens of thousands of automotive mechanics and hobbyist. Add to that, other companys have introduced "compatible" green extended life coolants...DexCool is becoming a modern day "dinosaur"
With all due respect you are very wrong. Ford and chryselr are going to dex-cool product in 2011, GM still uses it. BMW, Mercedes and Volkswagon all started using it last year as well as Volvo and a few others. GM's issues were with cooling system design, not the coolant. OAT technology is simply the best there is right now. The automakers are all on board. Please do some research and you will find this to be true. I just changed the dex in my 2005 Cadillac, and it is crystal clear, no corrosion in the cooling system.
 

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motorking
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maybe one of you kind fellas could run me through the steps of backflushing the heater core? my heat has been colder than most brand new cars AC. i live in florida so i only need heat about a month out of the year and since i never figured out what the problem was i just decided to suck it up and drive with gloves on
i know its the dexcool goop because my first winter with it my dad squeezed the heater core hoses and it loosened up and gave me about 2 or 3 days of heat. which was enough because it got hot again after that
but yeahh...im planning on moving to ohio by 2011 so itd be nice to have heat...
Raviolli,
You should pull the hoses off your heater core. Go to the autoparts store, get a piece of hose that fits one of the heater core nipples about a foot long. Go to the hardawre store and get a garden hose adapter you can clamp to this hose. hook one end to your garden hose and the other to a heater core nipple. Turn the garden hose on slowly! A pile of ugly goo is going to come out. After you do this, remove your thermostat and put it back together without a t-stat. Fill with water and a jug of Prestone super flush, let the car run for an hour and drain. Fill with water again and run for 15 minutes and drain. re-install thermostat and fill with your favorite brand of extended life coolant in a 50/50 mixture using either distilled or deionized water. This water is available at any grocery store. Good luck from your friends at prestone:cool:
 

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It's easier to find an old piece of hose and just cut it off. That's what I did with a bad hose I had laying around. Put it on the larger of the two end on the heater core.
 

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With all due respect you are very wrong. Ford and chryselr are going to dex-cool product in 2011, GM still uses it. BMW, Mercedes and Volkswagon all started using it last year as well as Volvo and a few others. GM's issues were with cooling system design, not the coolant. OAT technology is simply the best there is right now. The automakers are all on board. Please do some research and you will find this to be true. I just changed the dex in my 2005 Cadillac, and it is crystal clear, no corrosion in the cooling system.
Good Luck with that...myself and the vast majority of the people who discuss this topic both online and in shops, etc. totally disagree with you. However, I understand you have to "tow the company line" since this is your "bread and butter" but your fooling no one here!
 

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I just got done with this prob. But first started off with the blaze gettin hot . Two water pumps a radiator and cap, hoses and a flush fixed it. But I have done the backflush on my core and I get the so called goop out and I will have great heat for bout 2-3 days then it starts blowing semi warm. I have done backflushing twice now and got same results. Should I keep backflushing until completely resolved?? Is or would it be safe to disconnect the core hoses off firewall and some how shoot some radiator flush to the core and let it sit for awhile??? Will that break the goop down?? Then backflush?will the prestone flush work if it just sit in the core for a few hours???Thanks fellas
 

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Should I keep backflushing until completely resolved?? Is or would it be safe to disconnect the core hoses off firewall and some how shoot some radiator flush to the core and let it sit for awhile??? Will that break the goop down?? Then backflush?will the prestone flush work if it just sit in the core for a few hours???Thanks fellas
I hooked my garden hose directly to a stub of heater hose and flushed it both ways til the "Dexcool Goop" came out and the water ran clear.Although some people here (company man) would have you believe that Dexcool is the greatest coolant ever developed...
 

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Yeah that's how I backflushed mine took both hoses off the core nipples on firewall, ran water both ways until got clear, got all the goop out and like said the heat will be hot as the hell beneath us for a few days then just get semi warm? Should I just keep flushing? It gets cold here in Texas and I got to have my heat. Any suggestions?? Thanks guys.
 
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