Question about 1986 Pontiac Fiero

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Pontiac Fiero Heater Core

I need a little assistance on replacing the heater Core in my 85 Fiero. Is this a job that is a headache or No?

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No its actually really easy i just did it about 3 weeks ago. right under the dash on the passenger side the is a black box unscrew the cover on the side of it and the heater core is right there then you have to  disconnect the hoses under the hood which might be the hardest part after that unbolt the straps holding the heater core on. I keep the straps on till i get the hoses off because then the heater core don't move when you are trying to get the hoses off. Then all you have to do is put it back together.

Posted on Nov 23, 2008

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Fairly simple job. I'll assume you have A/C and not a 'heater only' car. Down by the passenger's feet sits the HVAC module. Big, black, odd-shaped box directly behind 'map pocket' on pass. side dash. You'll be taking off the curved portion that is the cover for the heater core.

BEWARE!! About half the time I replace one of these, it's because it was leaking coolant into the ducting, and fog would form at the base of the windshield. When you take the curved heater core access cover off, coolant may or may not leak all over you and your nice carpet. Take precautions, you've been warned.

Up under the hood, on the pass. side of the spare tire compartment, you will see the windshield fluid reservoir. Right behind it are the two heater hoses that deliver piping hot coolant to the core in your dash. Being aware that coolant is about to leak on you and the spare tire, remove the hose clamps and slide the hoses off of the core's hose fittings. There is a gooey seal that is supposed to help keep air where it belongs. Save it and put it on the new core.

Inside the car, now take off the curved part of the HVAC module. Then you'll see the old core and hopefully not much green/rust mess. You'll hopefully see how the core is held in place (by a bracket at the end nearest your face) with two screws. Take those out, swap the core, and repeat the removal process in reverse.

Incidentally, make sure you 'burp' the cooling system properly once you are done. It does really make a difference if you use tap water mixed with anti-freeze. It causes the suspended particles in the coolant to gel up and plug up your cooling systems nooks and crannies. And if you think about using straight tap water, stop thinking. How do you think the core went out in the first place? Internal corrosion/electrolysis ate away at the brass/zinc contained in the core as a sacrificial anode from not using a corrosion inhibitor. Sorry about the run-on sentence.

Posted on Aug 11, 2014

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