Heater core replacement - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Prerunner1982 · 10-03-2005, 12:08 AM

Just thought i would see if there were any tricks that would be beneficial to me, mine started leaking a few days ago, i by passed it temporarly.. but with winter coming i need it fixed... any ideas would help...

apstguy · 10-03-2005, 01:04 AM

Here is a full write up - I used it to replace mine. Complete instructions!

http://coloradok5.com/heatercore.shtml

Prerunner1982 · 10-03-2005, 12:37 PM

Grim Reaper · 10-07-2005, 10:46 PM

Quote:

Originally Posted by Prerunner1982

Prerunner1982 · 10-07-2005, 10:52 PM

ummm hi grim..

Get to start on this in the AM.. shouldnt be quite as cold as it has been lately.. and may have some help.. so hopefully it wont take me 4-5hrs...

ocbaud · 10-07-2005, 11:22 PM

ewww..... heater core

that sounds like its gonna suck to fix

Grim Reaper · 10-07-2005, 11:22 PM

Quote:

Originally Posted by Prerunner1982

ummm hi grim..

Get to start on this in the AM.. shouldn't be quite as cold as it has been lately.. and may have some help.. so hopefully it wont take me 4-5hrs...

You going to try and do it without dropping the inner? Thats really the worst part of it if any of those bolts are rusted. I just couldn't get on that one bolt on the bottom without dropping it.

I take my time doing stuff and if your going along without distraction it can be done in less.

Prerunner1982 · 10-07-2005, 11:34 PM

dropping the inner fender? i might as well.. at this point.. if its not that much more work.. and will make the heater core easier...

FLAGG · 10-07-2005, 11:51 PM

Funny, when I did my heater core a few years back I never dropped the inner fender. I don't recall if it was that big a pain in the ass or not, though.

What I do recall is the bolts/nut had that undercoating-like spray on them, and instead of trying to remove it first I just tried to muscle the nuts off it. One of the bolts paid the price in the end. Live and learn I guess.

boxrodz · 10-08-2005, 12:41 AM

I replaced mine eariler in the year. Like Flagg, I didn't have to remove the inner fender. If you have the right extensions and an universal joint, you shouldn't have to remove the inner fender. It wasn't too bad of a job. Just be careful with the coolant once you get the hoses and the core loose. The tough part for me was removing the hoses from the core. I ended up just cutting the ends off.

Prerunner1982 · 10-08-2005, 12:49 AM

hmm guess i will give it a shot with the inner on then... will just have to see..

79BIG10 · 10-08-2005, 01:24 AM

When I replaced mine the hardest part was getting the nuts off that were tarred over

a28doc · 10-08-2005, 01:46 AM

at least it isnt like the newer s10 blazers where u have to remove the whole dash to get to it lol did my old 95 5 times before i sold it
Doc

FLAGG · 10-08-2005, 11:41 AM

My first car was a 1980 Pontiac Sunbird (the old rear wheel drive Monza style). I had to replace the heater core in it, and a buddy of mine helped out. GM, in it's infinite wisdom, had bolted the housing to the firewall except for one stud that had the housing force-fit over it. Talk about a pain in the ass. After about 10 minutes of wrestling with it, I wandered off to find something that might help. When I came back I found my friend latched onto the housing and thrashing like an animal caught in an electric fence. Funniest thing I ever saw. And damned if he didn't get the housing free, though.

a28doc · 10-08-2005, 01:58 PM

too bad you didnt get pics of that
Doc

84_chevrolet · 10-08-2005, 05:59 PM

undefinedok just rplaced mine today took from 10am to about 3 pm did not pull the inner fender was able 2 get to the bolt with a 1/4 inch drive ratchet and socket, pulled the box from the inside replaced it then as going back duct taped where every piece of duct work went together and it blows 3 times better and cools and heats way better now

Prerunner1982 · 10-08-2005, 06:24 PM

took me about 4hrs.. which is about what i had anticipated.. i didnt hurry.. i fiddle farted around a bit... had to get the radio out.. hook it up.. find the right station (OU game).. get out the tools, get organized, clean out the cab of the truck...

All in all it wasnt too bad.. i did things i know i wont have to do next time... but thats how you learn.. i didnt get the hoses back on yet.. as i forgot to grab coolant and water while i was out today, but no biggy....the heater core is still bypassed.. so i will fill it up on monday..

I had more trouble getting the whole case back on the fire wall.. its the only time i had to call my wife to come hold it...

certainly dont want to do it again anytime soon.. but it wasnt all that bad..

Grim Reaper · 10-09-2005, 01:18 AM

good deal. Just remember the line from the intake is 5/8's and it goes to the bottom of the two heater core inlets The return line is 3/4 and goes to either the water pump or the radiator depending on how your truck as set up.

KShortell · 10-09-2005, 10:56 PM

I'm glad you had success. I replaced mine last December- not a fun job, but nowhere as bad as on an old Dodge motorhome chassis. I helped my granddad work on his squirrel cage fan once. Talk about a pain!

Overcamber · 10-10-2005, 08:32 PM

I changed mine yesterday as well. the 3 studs1/4 that stick out may be a problem but if you have a 1/4-20 thread chaser or a 1/4" die just run that over the exposed portion of the stud beofre you try to remove the nuts and you should have no problem with those whosoever..I didnt anyways..

*Zilverado* · 10-11-2005, 04:16 PM

Quote:

Originally Posted by Prerunner1982

...certainly dont want to do it again anytime soon.. but it wasnt all that bad..

Assuming the core doesn't leak when you "charge 'er up", you'll be fine for quite a while I'm sure. When I did mine a couple of years back, the first core I got leaked somethin' fierce. Fortunately, I pressure tested it with a garden hose before installing it. Got the second core (for a bit more money) and all has been great ever since.

So, hopefully your core is good (I'm sure it will be).

koreric75 · 10-28-2005, 07:29 PM

Well, attempted to do a quick 3 hour core change, but those studs that stick through suck, i spent about 10 to 15 minutes on each cleaning the stud end, and when i went to remove the nuts the studs twisted off in the middle, so all but one stud is thrashed. I thought it would be a good idea at this point to go ahead and remove the non-functional a/c coil and canister since the compressor and condenser aren't coming back, but the freaking !@##$ plastic box was like peanut brittle and is now in pieces on the driveway. Tsk tsk tsk, temper temper...lol, anyway now i'm looking through all the old posts for the user that has the fabricated panel to just put the blower back on with out the ac box.

**swervin ervin** · 10-28-2005, 07:48 PM

This probably won't help you since you say your box is broken to pieces, but I removed all my AC stuff long ago. I didn't won't to get into a bunch of bodywork and removing crap under the dash, so I just cut off most of my AC box. In order to keep the heat, you can't just do away with it. The heater core is not too far behind there. The pic below is an old shot of how mine looks. I cut it off and put another metal panel to cover it up. It has worked flawlessly and looks decent. Some day I will most likely remove all the AC stuff under the dash and go with just heat only. Then I will also fix the firewall and use a plain heater box too. Anyway, maybe this photo will help you some.

koreric75 · 10-28-2005, 08:33 PM

Wow, that's clean looking, i had intended to do something along those lines if i could've removed the box intact, i have a pretty decent salvage yard here, actually a few so i guess i'll be hitting them in the morning looking for at least one to mod. I was thinking about going ahead and swapping the heater core since i have a new one already, but will it do me any good since i can't really mount the fan or force air through the duct. It's got me thinking about some different stuff. One idea if I could do it is to take 5" round tube, install a turbine type fan in the tube along with some type of mechanical cutoff cable mounted near the heater controls, then i would need a fabricated piece that would take the 5" tube to the rectangular shaped duct leading to the heater core, this piece makes me think of the rectangular to circular ducting used in homes for registers in the ceiling or maybe the top of an air box on a vehicle, all the while keeping in mind the heater hoses have to route to the heater core inlet and outlet. Well any ideas welcome.

**swervin ervin** · 10-28-2005, 09:18 PM

If you are going to fix your box like mine, I would go ahead and put the new heater core in. Everything on mine works except my AC. It blows air still but it's not cold anymore. You can see the fan is installed in the factory location.

10-03-2005, 12:08 AM	#1
Prerunner1982 Registered User Join Date: Oct 2002 Location: Edmond, OK Posts: 5,906	Heater core replacement Just thought i would see if there were any tricks that would be beneficial to me, mine started leaking a few days ago, i by passed it temporarly.. but with winter coming i need it fixed... any ideas would help... __________________ Jon 1982 Chevy Silverado 350/th350.... RETIRED 1993 Jeep XJ 2 door(Cherokee) 4wd 4.0ltr/AX-15 (5spd)/NP231 .... Oklahoma Roll Call

10-03-2005, 01:04 AM	#2
apstguy LED King Join Date: Jan 2003 Location: Sacramento, CA Posts: 2,088	Here is a full write up - I used it to replace mine. Complete instructions! http://coloradok5.com/heatercore.shtml __________________ Tyler 1985 C10 305 w/ Bowtie OD TH700R4 3.42 LSD 202,000 miles 2006 Ford Focus ZX3 5-speed Stick 2016 Chevy Spark EV Gone: 2002.5 VW GTI 24v VR6 Gone: 2008 VW R32

10-08-2005, 12:41 AM	#10
boxrodz Until Seventy Times Seven Join Date: Feb 2005 Location: Rocky Mountain Front Range Posts: 1,301	I replaced mine eariler in the year. Like Flagg, I didn't have to remove the inner fender. If you have the right extensions and an universal joint, you shouldn't have to remove the inner fender. It wasn't too bad of a job. Just be careful with the coolant once you get the hoses and the core loose. The tough part for me was removing the hoses from the core. I ended up just cutting the ends off. __________________ boxRODz 1983 C10 SWB Fleetside When two halves is gone, there's nuthin left. Two nothings is nuthin. That's mathematics son. You can argue with me but you can't argue with figures. Two half nothings is a whole nuthin...

10-08-2005, 01:24 AM	#12
79BIG10 I'm back with 2nd truck! Join Date: Feb 2002 Location: Texas Posts: 3,775	When I replaced mine the hardest part was getting the nuts off that were tarred over __________________ 1979 Chevrolet Bonanza Big10 "Tootsie Roll" 1985 Chevrolet Silverado (wife's) Member of the Southern Bowties Club "Don't underestimate how sexy a fat man who drinks to excess can be." Homer Simpson

10-08-2005, 01:46 AM	#13
a28doc '87 V20 4x4 Join Date: Jun 2004 Location: South Western Ohio Posts: 1,073	at least it isnt like the newer s10 blazers where u have to remove the whole dash to get to it lol did my old 95 5 times before i sold it Doc __________________ '86 K5 Blazer 4x4 FOR SALE '87 v20 4X4 '99 S10 Blazer 4X4

10-03-2005, 12:37 PM	#3
Prerunner1982 Registered User Join Date: Oct 2002 Location: Edmond, OK Posts: 5,906

10-07-2005, 10:52 PM	#5
Prerunner1982 Registered User Join Date: Oct 2002 Location: Edmond, OK Posts: 5,906	ummm hi grim.. Get to start on this in the AM.. shouldnt be quite as cold as it has been lately.. and may have some help.. so hopefully it wont take me 4-5hrs...

10-07-2005, 11:22 PM	#6
ocbaud Garage Queen Material Join Date: Oct 2002 Location: USA Posts: 4,129	ewww..... heater core that sounds like its gonna suck to fix

10-07-2005, 11:34 PM	#8
Prerunner1982 Registered User Join Date: Oct 2002 Location: Edmond, OK Posts: 5,906	dropping the inner fender? i might as well.. at this point.. if its not that much more work.. and will make the heater core easier...

10-07-2005, 11:51 PM	#9
FLAGG Registered User Join Date: Feb 2004 Location: St. Albert, Alberta, Canada Posts: 89	Funny, when I did my heater core a few years back I never dropped the inner fender. I don't recall if it was that big a pain in the ass or not, though. What I do recall is the bolts/nut had that undercoating-like spray on them, and instead of trying to remove it first I just tried to muscle the nuts off it. One of the bolts paid the price in the end. Live and learn I guess.

10-08-2005, 12:49 AM	#11
Prerunner1982 Registered User Join Date: Oct 2002 Location: Edmond, OK Posts: 5,906	hmm guess i will give it a shot with the inner on then... will just have to see..

10-08-2005, 11:41 AM	#14
FLAGG Registered User Join Date: Feb 2004 Location: St. Albert, Alberta, Canada Posts: 89	My first car was a 1980 Pontiac Sunbird (the old rear wheel drive Monza style). I had to replace the heater core in it, and a buddy of mine helped out. GM, in it's infinite wisdom, had bolted the housing to the firewall except for one stud that had the housing force-fit over it. Talk about a pain in the ass. After about 10 minutes of wrestling with it, I wandered off to find something that might help. When I came back I found my friend latched onto the housing and thrashing like an animal caught in an electric fence. Funniest thing I ever saw. And damned if he didn't get the housing free, though.

10-08-2005, 01:58 PM	#15
a28doc '87 V20 4x4 Join Date: Jun 2004 Location: South Western Ohio Posts: 1,073	too bad you didnt get pics of that Doc __________________ '86 K5 Blazer 4x4 FOR SALE '87 v20 4X4 '99 S10 Blazer 4X4

10-08-2005, 05:59 PM	#16
84_chevrolet Truck CRAZY! Join Date: Mar 2004 Location: douglas Posts: 81	advise undefinedok just rplaced mine today took from 10am to about 3 pm did not pull the inner fender was able 2 get to the bolt with a 1/4 inch drive ratchet and socket, pulled the box from the inside replaced it then as going back duct taped where every piece of duct work went together and it blows 3 times better and cools and heats way better now

10-08-2005, 06:24 PM	#17
Prerunner1982 Registered User Join Date: Oct 2002 Location: Edmond, OK Posts: 5,906	took me about 4hrs.. which is about what i had anticipated.. i didnt hurry.. i fiddle farted around a bit... had to get the radio out.. hook it up.. find the right station (OU game).. get out the tools, get organized, clean out the cab of the truck... All in all it wasnt too bad.. i did things i know i wont have to do next time... but thats how you learn.. i didnt get the hoses back on yet.. as i forgot to grab coolant and water while i was out today, but no biggy....the heater core is still bypassed.. so i will fill it up on monday.. I had more trouble getting the whole case back on the fire wall.. its the only time i had to call my wife to come hold it... certainly dont want to do it again anytime soon.. but it wasnt all that bad..



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10-09-2005, 01:18 AM	#18
Grim Reaper Registered User Join Date: Jul 2001 Location: Atlanta GA Posts: 1,704	good deal. Just remember the line from the intake is 5/8's and it goes to the bottom of the two heater core inlets The return line is 3/4 and goes to either the water pump or the radiator depending on how your truck as set up. __________________ Grim-Reaper 70 Pontiac LeMans Sport Convertible, worlds longest resto in progress Looking for 71-72 2wd Blazer or Jimmy Project

10-09-2005, 10:56 PM	#19
KShortell Registered User Join Date: Oct 2003 Location: Chesapeake, VA Posts: 724	I'm glad you had success. I replaced mine last December- not a fun job, but nowhere as bad as on an old Dodge motorhome chassis. I helped my granddad work on his squirrel cage fan once. Talk about a pain! __________________ Semper Paratus

10-10-2005, 08:32 PM	#20
Overcamber Overcamber Join Date: Mar 2005 Location: Skead ,Ontario Posts: 109	I changed mine yesterday as well. the 3 studs1/4 that stick out may be a problem but if you have a 1/4-20 thread chaser or a 1/4" die just run that over the exposed portion of the stud beofre you try to remove the nuts and you should have no problem with those whosoever..I didnt anyways..

10-28-2005, 07:29 PM	#22
koreric75 83C10SWB Join Date: Sep 2005 Location: Bossier City, Louisiana Posts: 69	Re: Heater core replacement Well, attempted to do a quick 3 hour core change, but those studs that stick through suck, i spent about 10 to 15 minutes on each cleaning the stud end, and when i went to remove the nuts the studs twisted off in the middle, so all but one stud is thrashed. I thought it would be a good idea at this point to go ahead and remove the non-functional a/c coil and canister since the compressor and condenser aren't coming back, but the freaking !@##$ plastic box was like peanut brittle and is now in pieces on the driveway. Tsk tsk tsk, temper temper...lol, anyway now i'm looking through all the old posts for the user that has the fabricated panel to just put the blower back on with out the ac box. __________________ Koreric75 2003 Suburban Z-71 4x4 5.3L 83 C10 SWB FOR SALE 350ci/700Raptor Jr Picture&Progress Page

10-28-2005, 07:48 PM	#23
swervin ervin You get what you pay for Join Date: Dec 1999 Location: Cherryville, NC Posts: 4,798	Re: Heater core replacement This probably won't help you since you say your box is broken to pieces, but I removed all my AC stuff long ago. I didn't won't to get into a bunch of bodywork and removing crap under the dash, so I just cut off most of my AC box. In order to keep the heat, you can't just do away with it. The heater core is not too far behind there. The pic below is an old shot of how mine looks. I cut it off and put another metal panel to cover it up. It has worked flawlessly and looks decent. Some day I will most likely remove all the AC stuff under the dash and go with just heat only. Then I will also fix the firewall and use a plain heater box too. Anyway, maybe this photo will help you some. Attached Images __________________ Mike 1985 Chevy C-10

10-28-2005, 08:33 PM	#24
koreric75 83C10SWB Join Date: Sep 2005 Location: Bossier City, Louisiana Posts: 69	Re: Heater core replacement Wow, that's clean looking, i had intended to do something along those lines if i could've removed the box intact, i have a pretty decent salvage yard here, actually a few so i guess i'll be hitting them in the morning looking for at least one to mod. I was thinking about going ahead and swapping the heater core since i have a new one already, but will it do me any good since i can't really mount the fan or force air through the duct. It's got me thinking about some different stuff. One idea if I could do it is to take 5" round tube, install a turbine type fan in the tube along with some type of mechanical cutoff cable mounted near the heater controls, then i would need a fabricated piece that would take the 5" tube to the rectangular shaped duct leading to the heater core, this piece makes me think of the rectangular to circular ducting used in homes for registers in the ceiling or maybe the top of an air box on a vehicle, all the while keeping in mind the heater hoses have to route to the heater core inlet and outlet. Well any ideas welcome. __________________ Koreric75 2003 Suburban Z-71 4x4 5.3L 83 C10 SWB FOR SALE 350ci/700Raptor Jr Picture&Progress Page

10-28-2005, 09:18 PM	#25
swervin ervin You get what you pay for Join Date: Dec 1999 Location: Cherryville, NC Posts: 4,798	Re: Heater core replacement If you are going to fix your box like mine, I would go ahead and put the new heater core in. Everything on mine works except my AC. It blows air still but it's not cold anymore. You can see the fan is installed in the factory location.

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