Removing and Replacing the Heater Core on an '80-'86 Ford Truck

Replacing the heater core on an '80 to '86 Ford full-size truck with factory air conditioning is a very straightforward process. However, I gather from the 1984 factory shop manual that the same task on a truck that doesn't have factory a/c is considerably more daunting, requiring the removal of much of the dash.. Typically, heater core replacements are due to the core itself failing, allowing coolant to go into the cab. I got lucky; the core on my truck was actually okay. As the picture above shows, the hose nipples had been damaged by people carelessly removing and installing hoses over the years. At this point, it was bad enough that I could not get replacement hoses to seal properly after removing the heater hoses for the first time since I acquired the truck. It might have been possible to simply repair the hose nipples, but I decided to play it safe and replace the entire core.

I would suggest beginning by removing the heater hoses. It should go without saying that the engine should be cold and pressure in the cooling system should be first relieved by removing the radiator cap. It shouldn't be necessary to entirely drain the cooling system, although this would be a good opportunity to flush out the system if it hasn't been done recently. A catch basin (bucket, etc) can be used to collect the coolant that will come out of the heater hoses when you remove them. I would suggest using this as an opportunity to replace the hoses, although that's a personal judgement call. Other than removing the hoses (and possibly pushing on the hose nipples to help remove the heater core), this task will be performed from inside the cab on the passenger's side.

Getting to the heater core on this truck is a simple matter of removing the glove box insert and the lower trim insulation (basically a plastic kick panel with foam insulation on the other side; note that this may already be gone on some trucks), and removing the access panel that serves as the back of the heater core box. The procedure may be similar on '87 to '91 trucks, and may even be similar on '92 to '97 trucks, but I can't say that with any certainty. In this picture, I'm removing one of the five screws that holds the glove box insert in place.

The glove box insert is removed, revealing some wiring and the heater core box. The heater core box is to the right, with the two screw heads in the center of the picture being the leftmost of the screws holding the access panel in place

Removing one of the access panel screws on the right side with a ratcheting screwdriver with a socket attachment.

The access panel is removed, exposing the heater core. From here, it is a simple matter of pushing the heater core out. There is insulation on either side of the heater core, so it may feel like the core is being held in place by something. With some effort, it should just pull right out. With the hose nipples at the very top, the heater core will still be full of coolant, so care should be taken to not let it tip while bringing it out.

The heater core is out! You can see one of the holes on the top right where the hose nipples go through the firewall into the engine compartment, along with the empty box. Installing the replacement heater core is simply the reverse of removing the old one. I would suggest removing any insulation that's attached to the old heater core and install it with the replacement. The insulation keeps air from being able to get around the heater core as it sits in its box, leading to more efficient operation. Certainly, the heater on this truck will get it hot enough to run me out of the cab! I wish I could say the same for the air conditioning. I would also suggest cleaning out the inside of the box. If other trucks are anything like mine, the inside of the box was VERY dusty. Hopefully, with cleaning out the inside of the box, less dust will come of the the heater and a/c ducts.

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Page updated November 14th, 2005

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