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

68gmcjon · 10-11-2002, 09:45 PM

Does anyone have a clue how to get the heater core out of a 68' GMC w/ a/c?

*Fast68Chevy* · 10-12-2002, 12:20 AM

easy cake if no a/c, if you look all around edges of the black palstic air box under the hood there are bolts and nnuts and screws, remove them all and then go inside cab and remove what ones you need to- if any- top be able ot pull the box off the firewall under the hood. dropping inner fender out of way would help but if you liv ein rust belt then youll have to buy new clip nuts fr those bolts cuz theyll just snp on you when you try removing the bolts.

good luck

chewed 71'er · 10-14-2002, 04:38 PM

There are four studs on the heater core housing that go through the firewall. In engine compartment, the 2 upper nuts are accessible, but the 2 lower ones are tucked under the evaporator housing. As mentioned above, you can pull the inner fender for access to the lower 2, or use a 7/16 deep-well, flex joint, and a long 1/4 inch drive extention (however, I have a 350 SB - your BB probably takes up more room).
Inside the cab, you'll need to remove the heat/defrost diverter valve housing, 'S' duct, and AC/heater vent diverter box. Now there are only 2 bolts holding the heater core housing in place, 1 upper and 1 lower. As a note, the blower motor wire and relay are located on the upper right-hand side of the heater core housing, in a tight spot. Suggest setting housing on floor board, THEN removing wiring and/or relay. Hope this helps.

71GMC_3/4T · 10-14-2002, 05:47 PM

It is much easier if you remove the fender well. I also seem to remember fighting the fan squirrel cage to get the box slid off. You have to remove a hood hinge to get the fan out though.
It's also a lot easier if you remove the glove box door and cardboard box.
I found about a half bushel of leaves in mine.
Also, take out your old heater core and take it with you when you go for a replacement. Mine was somewhat smaller and I ended up using it anyway with some heavy foam to bush it.

Blazer1970 · 10-15-2002, 08:08 AM

On and A/C truck, you remove the heater core from inside the cab. The only thing you remove from under the hood is the nuts that hold the box to the inside of the firewall. You do not screw with the fan, the hood hinges, or anything else under the hood.

10-11-2002, 09:45 PM	#1
68gmcjon Got earplugs? Join Date: Mar 2002 Location: Winfield, Kansas Posts: 556	Heater Core Does anyone have a clue how to get the heater core out of a 68' GMC w/ a/c? __________________ 1968 GMC Original A/C, bucket seats, PS,PB 396 bored to 402, Dynomax cerama-coat headers, Super 40 Flowmasters, 272/284 Crane cam, Crane gold roller rockers, holley 750 cfm double pumper, Edelbrock Performer RPM intake, HEI ignition, 9.5:compression Alltogether 411HP and 446ft/lbs Dana 60 w/ 3.54 gears Turbo 400 tranny Why would you have anything other than a big block? HAHA

10-14-2002, 05:47 PM	#4
71GMC_3/4T Weapons Of Construction Join Date: Apr 2000 Location: Colorado, USA Posts: 1,095	It is much easier if you remove the fender well. I also seem to remember fighting the fan squirrel cage to get the box slid off. You have to remove a hood hinge to get the fan out though. It's also a lot easier if you remove the glove box door and cardboard box. I found about a half bushel of leaves in mine. Also, take out your old heater core and take it with you when you go for a replacement. Mine was somewhat smaller and I ended up using it anyway with some heavy foam to bush it. __________________ 1971 GMC 2500, 402/TH400 4.10 Daily Driver Lafayette, CO

10-15-2002, 08:08 AM	#5
Blazer1970 Registered User Join Date: Dec 1999 Location: Old Mission, MI, USA Posts: 2,510	On and A/C truck, you remove the heater core from inside the cab. The only thing you remove from under the hood is the nuts that hold the box to the inside of the firewall. You do not screw with the fan, the hood hinges, or anything else under the hood. __________________ Tim

10-12-2002, 12:20 AM	#2
Fast68Chevy Account Suspended Join Date: May 2000 Location: IL Posts: 0	easy cake if no a/c, if you look all around edges of the black palstic air box under the hood there are bolts and nnuts and screws, remove them all and then go inside cab and remove what ones you need to- if any- top be able ot pull the box off the firewall under the hood. dropping inner fender out of way would help but if you liv ein rust belt then youll have to buy new clip nuts fr those bolts cuz theyll just snp on you when you try removing the bolts. good luck

10-14-2002, 04:38 PM	#3
chewed 71'er Registered User Join Date: Mar 2002 Location: KC, NW Missouri Posts: 144	There are four studs on the heater core housing that go through the firewall. In engine compartment, the 2 upper nuts are accessible, but the 2 lower ones are tucked under the evaporator housing. As mentioned above, you can pull the inner fender for access to the lower 2, or use a 7/16 deep-well, flex joint, and a long 1/4 inch drive extention (however, I have a 350 SB - your BB probably takes up more room). Inside the cab, you'll need to remove the heat/defrost diverter valve housing, 'S' duct, and AC/heater vent diverter box. Now there are only 2 bolts holding the heater core housing in place, 1 upper and 1 lower. As a note, the blower motor wire and relay are located on the upper right-hand side of the heater core housing, in a tight spot. Suggest setting housing on floor board, THEN removing wiring and/or relay. Hope this helps.



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