Putting in a new heater core - The 1947 - Present Chevrolet & GMC Truck Message Board Network

lukecp · 02-20-2003, 10:05 PM

After two years of lukewarm heat, and a slow fan, i finally broke down and bought a new heater blower motor and heater core for my non A/C '72. I put the new blower motor in the other day, and it blows twice as fast, but the heat isn't that warm. So i plan to put the new heater core in this weekend. So, how should i go about replacing the heater core? First i drain most of the cooling system, disconnect the hoses from the heater, remove the heater box and then put in a new core, right? I remember someone saying several years ago that he had to remove the cowl panel to replace his core. If so, i just unbolt the cowl by the hood hinges, remove the antenna, windshield wipers, and the screws in the middle of the cowl, or is there anything else?
Thank your for any help.

BLACK AND BLUE 67-72 · 02-20-2003, 10:14 PM

No, you don't have to remove the Cowl, just the Right hood hinge, and there is a bolt at the bottom that you can't hardly reach because of the inner fender. I just drilled it out from the inside of the cab then replaced it with a regular bolt, because I could not break the inner fender bolts loose. Other than that I had no problems.Then I used caulking on the box where it seals to the firewall so when I washed it it would not leak.

Willy Prost · 02-20-2003, 10:20 PM

I don't remember removing the cowl when I replaced the heater core. I did remove the fender well for better access to the botom bolt that holds the cover to the heater box though. You might well find a bunch of trash blocking the heater core after you get the cover off. Field mice are great at shredding paper napkins left in the cab to make bedding for that nice warm heater core.

lukecp · 02-20-2003, 10:33 PM

Thanks for the help. I was going to remove the heater core and clean it out, but after i check the price for a new core ($20), i figured i might as well replace it as long as i have it out. I may go ahead and yank off the cowl anyway and clean all the pine needles and other trash out of the cowl vents while im at it.......

oldsub86 · 02-20-2003, 10:47 PM

It will be best if you can drop the right front fender liner. Then you can get at the bolts on the bottom of the housing without any problems.

One further word of advice so that you avoid the problem that I have. When I took my truck apart I found that there was a piece of rubber that cushions or holds the core in place inside the housing. It was sort of shot so I looked around for something likely to replace it. I used a chunk of carpet underlay. It was a bad idea as everytime it gets heated up it smells like rubber. I thought it would get better over time but it has been years and it still smells when it heats up. I don't drive the truck much in cold weather so I have yet to fix it but it is on my mental list of things that need to be done.

72shadetree · 02-21-2003, 12:19 AM

on the hood hinge i just loosend mine up and it moved enough but i didnt have the hood on so it was a little easier

PanelDeland · 02-22-2003, 04:07 PM

Mark a line around the hood hinge so that you can get the alignment back.

lukecp · 02-22-2003, 07:05 PM

I got new core in yesterday. Boy, it does feel good to be warm in the truck

. I did drop down the inner fender, but the plastic around the bolt was broken off, so i didn't need to. It was actually an easy job. With a friend to help me take off the hood, it took up maybe 1.5 hours. Thanks for all the help.

EdB · 02-22-2003, 11:07 PM

Lucus,

Did you check your heater control valve. My truck has
a vacum operated unit and I have had to replace it
a couple of times.

There is a built in valve on the heater control box. The one
in my truck is leaking and I run the line directly to the carb.

I had it out a few years ago and it was not leaking then.

The leak can sure effect gas milage.

EdB

Longhorn Man · 02-23-2003, 12:06 AM

EdB, the valve you speak of should only be installed on A/C trucks.

EdB · 02-24-2003, 12:47 AM

Lucus,

Forgive me for not seeing that you don't have an AC truck.

Are you sure it is the core. It might have a mechanical
control valve. It could also be a loose connection on the
door that routes the air.

You can always unhook the hoses: run a garden hose to
the inlet; run the other hose over the fender; turn on the
water hose and check the flow.

We talked about this today. I have only changed out about
a half dozen on various vehicles. A friend, who has many
years experience, cannot remember every changing one
out because it was stopped up. It has always been because
they were leaking.

Just my thoughts.

Forgive me Longhorn.

EdB

02-20-2003, 10:05 PM	#1
lukecp Formerly yellow72custom Join Date: May 2001 Location: Austin, TX Posts: 7,531	Putting in a new heater core After two years of lukewarm heat, and a slow fan, i finally broke down and bought a new heater blower motor and heater core for my non A/C '72. I put the new blower motor in the other day, and it blows twice as fast, but the heat isn't that warm. So i plan to put the new heater core in this weekend. So, how should i go about replacing the heater core? First i drain most of the cooling system, disconnect the hoses from the heater, remove the heater box and then put in a new core, right? I remember someone saying several years ago that he had to remove the cowl panel to replace his core. If so, i just unbolt the cowl by the hood hinges, remove the antenna, windshield wipers, and the screws in the middle of the cowl, or is there anything else? Thank your for any help. __________________ '72 Chevy C10 Mild 350/TH350/3.07. Ochre/White. Old high school ride. '70 GMC C2500 '62 327 4bbl/SM465/4.56-geared Dana 60. White/White. Project or parts truck. '97 Saturn SL DD. 1.9/5-speed. 40+ highway mpg

02-20-2003, 10:14 PM	#2
BLACK AND BLUE 67-72 Firefighter Join Date: Feb 2001 Location: Yellville, Ar, USA Posts: 1,943	No, you don't have to remove the Cowl, just the Right hood hinge, and there is a bolt at the bottom that you can't hardly reach because of the inner fender. I just drilled it out from the inside of the cab then replaced it with a regular bolt, because I could not break the inner fender bolts loose. Other than that I had no problems.Then I used caulking on the box where it seals to the firewall so when I washed it it would not leak. __________________ '72 Chevy SWB 350 Auto '67 GMC LWB 350 4 speed '70 Chevy 4x4 Stepside 350 Auto Yellville, Ar. USA Last edited by BLACK AND BLUE 67-72; 02-20-2003 at 10:23 PM.

02-20-2003, 10:33 PM	#4
lukecp Formerly yellow72custom Join Date: May 2001 Location: Austin, TX Posts: 7,531	Thanks for the help. I was going to remove the heater core and clean it out, but after i check the price for a new core ($20), i figured i might as well replace it as long as i have it out. I may go ahead and yank off the cowl anyway and clean all the pine needles and other trash out of the cowl vents while im at it....... __________________ '72 Chevy C10 Mild 350/TH350/3.07. Ochre/White. Old high school ride. '70 GMC C2500 '62 327 4bbl/SM465/4.56-geared Dana 60. White/White. Project or parts truck. '97 Saturn SL DD. 1.9/5-speed. 40+ highway mpg

02-20-2003, 10:47 PM	#5
oldsub86 Registered User Join Date: Dec 2002 Location: Canada Posts: 695	It will be best if you can drop the right front fender liner. Then you can get at the bolts on the bottom of the housing without any problems. One further word of advice so that you avoid the problem that I have. When I took my truck apart I found that there was a piece of rubber that cushions or holds the core in place inside the housing. It was sort of shot so I looked around for something likely to replace it. I used a chunk of carpet underlay. It was a bad idea as everytime it gets heated up it smells like rubber. I thought it would get better over time but it has been years and it still smells when it heats up. I don't drive the truck much in cold weather so I have yet to fix it but it is on my mental list of things that need to be done. __________________ 1968 Chevy - 292 with a powerglide

02-21-2003, 12:19 AM	#6
72shadetree KEEP ON TRUCKING Join Date: Sep 2000 Location: martinsville va Posts: 2,563	on the hood hinge i just loosend mine up and it moved enough but i didnt have the hood on so it was a little easier __________________ 72 cheyenne 2wd lwb 71 k20 sons bassett va

02-20-2003, 10:20 PM	#3
Willy Prost Senior Member Join Date: Jan 2000 Location: Arlington, VA Posts: 398	I don't remember removing the cowl when I replaced the heater core. I did remove the fender well for better access to the botom bolt that holds the cover to the heater box though. You might well find a bunch of trash blocking the heater core after you get the cover off. Field mice are great at shredding paper napkins left in the cab to make bedding for that nice warm heater core.

02-22-2003, 04:07 PM	#7
PanelDeland I am a Referee of life. Join Date: Jun 2000 Location: Greensboro N.C. Posts: 13,992	Mark a line around the hood hinge so that you can get the alignment back. __________________ 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"

02-22-2003, 07:05 PM	#8
lukecp Formerly yellow72custom Join Date: May 2001 Location: Austin, TX Posts: 7,531	I got new core in yesterday. Boy, it does feel good to be warm in the truck . I did drop down the inner fender, but the plastic around the bolt was broken off, so i didn't need to. It was actually an easy job. With a friend to help me take off the hood, it took up maybe 1.5 hours. Thanks for all the help. __________________ '72 Chevy C10 Mild 350/TH350/3.07. Ochre/White. Old high school ride. '70 GMC C2500 '62 327 4bbl/SM465/4.56-geared Dana 60. White/White. Project or parts truck. '97 Saturn SL DD. 1.9/5-speed. 40+ highway mpg

02-22-2003, 11:07 PM	#9
EdB Registered User Join Date: Jan 2003 Location: Gulfport Ms Posts: 401	Lucus, Did you check your heater control valve. My truck has a vacum operated unit and I have had to replace it a couple of times. There is a built in valve on the heater control box. The one in my truck is leaking and I run the line directly to the carb. I had it out a few years ago and it was not leaking then. The leak can sure effect gas milage. EdB

02-23-2003, 12:06 AM	#10
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,690	EdB, the valve you speak of should only be installed on A/C trucks.

02-24-2003, 12:47 AM	#11
EdB Registered User Join Date: Jan 2003 Location: Gulfport Ms Posts: 401	Lucus, Forgive me for not seeing that you don't have an AC truck. Are you sure it is the core. It might have a mechanical control valve. It could also be a loose connection on the door that routes the air. You can always unhook the hoses: run a garden hose to the inlet; run the other hose over the fender; turn on the water hose and check the flow. We talked about this today. I have only changed out about a half dozen on various vehicles. A friend, who has many years experience, cannot remember every changing one out because it was stopped up. It has always been because they were leaking. Just my thoughts. Forgive me Longhorn. EdB

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