Clogged heater core? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

PanelDeland · 11-01-2008, 04:35 PM

Is this a common problem? I think that is the problem.Everything in my wifes Blazer seems fine coolant is full and flows and the heater hose on one side gets hot but the other side stays cool.I checked at the firewall and think the core may be clogged.I just fixed this problem on my Dodge Dakota which is probably why I checked.Any help or Ideas would be appreciated.

BTW I don't work on this thing much,and I'm building a 68 so I spend most of my time over there.

BTW It's a 2000 if there's a difference.

BarryB · 11-01-2008, 05:24 PM

Sounds like the culprit to me. I don't know how you do it. But I take the bottom line off, and then hook a water hose to the other and see how well it flows.

mbgmike · 11-01-2008, 05:33 PM

These are a real pain in the ole butt. I agree with the above. you probably will have to flush it alot. I've done a couple of these and it takes a while to get all the crap out but most of it will after continued flushing. It beats replacing the core though. It is not an easy job. Unless it leaks I would not attempt to replace it unless you have alot of time. You will have to take the entire dash out.

PanelDeland · 11-01-2008, 07:15 PM

If it ain't broke don't fix it.I planned to just flush it.I already have a flushing adapter since I have to do my Dakota about once a year.I guess they use a smaller tube for heater cores than they used to.I have seen it on older vehicles but it seems like new ones clog more often.I was mostly curious as to whether this was common on the S-series like it is on the Dakota.I think I will flush the radiator also since it has never been done.the truck only has about 55,000 on it.

68C15 · 11-02-2008, 08:11 AM

the main reason these are a problem is 3 fold. first GM put this sealer stuff in the system. it acts just like your blood when it clots up on a cut. second is the fact that the core is mounted so high in relation to the rest of the cooling system. this leads us to reason #3. Dexcool gels up when it contacts air. every time you open the cap or anything else you get air in the system. just a small amount but it adds up. the air rises to the top (heater core) where it not only gels up it also makes the sealant do it's thing.
follow the hose that comes from the top of intake on pass. side. this is the feed to core. you need to remove both hoses and flush backwards with lots and lots of water.

PanelDeland · 11-02-2008, 04:48 PM

Backflushed and flushed several times and replaced the spring clamps with real ones.It will run you out now.Thanks for the ideas.

corn · 11-02-2008, 06:45 PM

Its a very common problem with the S10s...

Arad68 · 11-02-2008, 06:53 PM

Useful information...I would have never guessed this at first.

Hawker7 · 12-19-2008, 04:04 PM

make sure you are careful when flushing the heater core. I must have used too much pressure or did something else wrong and it broke the heater core. They are REAL pain to change. Here is what you get to do to your dash to change it out.

corn · 12-19-2008, 07:59 PM

Quote:

Originally Posted by Hawker7

make sure you are careful when flushing the heater core. I must have used too much pressure or did something else wrong and it broke the heater core. They are REAL pain to change. Here is what you get to do to your dash to change it out.

That does NOT look like fun!

11-01-2008, 04:35 PM	#1
PanelDeland I am a Referee of life. Join Date: Jun 2000 Location: Greensboro N.C. Posts: 13,993	Clogged heater core? Is this a common problem? I think that is the problem.Everything in my wifes Blazer seems fine coolant is full and flows and the heater hose on one side gets hot but the other side stays cool.I checked at the firewall and think the core may be clogged.I just fixed this problem on my Dodge Dakota which is probably why I checked.Any help or Ideas would be appreciated. BTW I don't work on this thing much,and I'm building a 68 so I spend most of my time over there. BTW It's a 2000 if there's a difference. __________________ The 47-present Chevrolet and GMC Truck Message Board Network,it's owners,moderators,members,and associates of any type should not be held responsible for my opinion. You can't fix stupid,not even with duct tape. "My appearance is due to the fact that "GOD" does punish you for having too much fun!" Barrett-Jackson has perfected alchemy,they make rust into gold! "You can lead a horse to water but you can't saddle a duck" "Cleverly disguised as a 'Responsible Adult' "Sometimes your Knight in shining armor is just a retard in tinfoil"

11-01-2008, 05:24 PM	#2
BarryB Senior Member Join Date: Jul 2006 Location: Blountville, Tn. Posts: 3,904	Re: Clogged heater core? Sounds like the culprit to me. I don't know how you do it. But I take the bottom line off, and then hook a water hose to the other and see how well it flows. __________________ We could learn a lot from crayons... Some are sharp; some are pretty;and some are dull. Some have weird names; and all are different colours;but they all have to live in the same box. You may be only one person in the world, But you may also be the world to one person. * Some mistakes are too much fun to only make once. Two rules in life. 1. Never sweat the small stuff! 2. Everything is small stuff!

11-01-2008, 07:15 PM	#4
PanelDeland I am a Referee of life. Join Date: Jun 2000 Location: Greensboro N.C. Posts: 13,993	Re: Clogged heater core? If it ain't broke don't fix it.I planned to just flush it.I already have a flushing adapter since I have to do my Dakota about once a year.I guess they use a smaller tube for heater cores than they used to.I have seen it on older vehicles but it seems like new ones clog more often.I was mostly curious as to whether this was common on the S-series like it is on the Dakota.I think I will flush the radiator also since it has never been done.the truck only has about 55,000 on it. __________________ The 47-present Chevrolet and GMC Truck Message Board Network,it's owners,moderators,members,and associates of any type should not be held responsible for my opinion. You can't fix stupid,not even with duct tape. "My appearance is due to the fact that "GOD" does punish you for having too much fun!" Barrett-Jackson has perfected alchemy,they make rust into gold! "You can lead a horse to water but you can't saddle a duck" "Cleverly disguised as a 'Responsible Adult' "Sometimes your Knight in shining armor is just a retard in tinfoil"

11-02-2008, 08:11 AM	#5
68C15 blood type; Retumbo Join Date: Jan 2004 Location: next to my reloading bench Posts: 10,269	Re: Clogged heater core? the main reason these are a problem is 3 fold. first GM put this sealer stuff in the system. it acts just like your blood when it clots up on a cut. second is the fact that the core is mounted so high in relation to the rest of the cooling system. this leads us to reason #3. Dexcool gels up when it contacts air. every time you open the cap or anything else you get air in the system. just a small amount but it adds up. the air rises to the top (heater core) where it not only gels up it also makes the sealant do it's thing. follow the hose that comes from the top of intake on pass. side. this is the feed to core. you need to remove both hoses and flush backwards with lots and lots of water.

11-02-2008, 04:48 PM	#6
PanelDeland I am a Referee of life. Join Date: Jun 2000 Location: Greensboro N.C. Posts: 13,993	Re: Clogged heater core? Backflushed and flushed several times and replaced the spring clamps with real ones.It will run you out now.Thanks for the ideas. __________________ The 47-present Chevrolet and GMC Truck Message Board Network,it's owners,moderators,members,and associates of any type should not be held responsible for my opinion. You can't fix stupid,not even with duct tape. "My appearance is due to the fact that "GOD" does punish you for having too much fun!" Barrett-Jackson has perfected alchemy,they make rust into gold! "You can lead a horse to water but you can't saddle a duck" "Cleverly disguised as a 'Responsible Adult' "Sometimes your Knight in shining armor is just a retard in tinfoil"

11-01-2008, 05:33 PM	#3
mbgmike Registered User Join Date: Aug 2005 Location: Pasadena,Tx /Pto Pta DR Posts: 5,415	Re: Clogged heater core? These are a real pain in the ole butt. I agree with the above. you probably will have to flush it alot. I've done a couple of these and it takes a while to get all the crap out but most of it will after continued flushing. It beats replacing the core though. It is not an easy job. Unless it leaks I would not attempt to replace it unless you have alot of time. You will have to take the entire dash out.

11-02-2008, 06:45 PM	#7
corn Registered User Join Date: Dec 2003 Location: here Posts: 5,789	Re: Clogged heater core? Its a very common problem with the S10s...

11-02-2008, 06:53 PM	#8
Arad68 Trucks N Tranzams Join Date: Dec 2002 Location: North Las Vegas, Nevada Posts: 816	Re: Clogged heater core? Useful information...I would have never guessed this at first. __________________ Don '68 Chevy LB 383 TH400/GV/373 posi '56 Chevy 4WD SWB '64 Chevy short stepside '79 Trans Am 455/TH2004R/12blt/4whldisc 95 Kia (Wifes car) 2002 S-10 extended cab pickup "God punishes small sins immediately"

12-19-2008, 04:04 PM	#9
Hawker7 Registered User Join Date: Jan 2008 Location: Raleigh, NC Posts: 321	Re: Clogged heater core? make sure you are careful when flushing the heater core. I must have used too much pressure or did something else wrong and it broke the heater core. They are REAL pain to change. Here is what you get to do to your dash to change it out. Attached Images



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